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Abstract Aerosol particle, carbonyl, and nicotine concentrations were analysed as pollutants affecting indoor air quality during the usage of electrically-heated tobacco product - the Tobacco Heating System (THS). Quantitative experimental variables included THS use intensity as number of parallel users (1, 3, or 5), distance to the bystander (0.5, 1, or 2 m), as well as environmental conditions in a chamber: ventilation intensity as air changes per hour (0.2, 0.5, or 1 h−1), and relative humidity (RH, 30, 50 or 70%). The real-time particle number (PNC), CO and CO 2 concentration, as well as off-line acetaldehyde, formaldehyde, nicotine, and 3-ethenylpyridine concentration was measured during and after the active usage. Use of THS resulted in a statistically significant increase of several analytes including nicotine, acetaldehyde, PM 2.5 , and PNC as compared to the background. The obtained levels were significantly lower (approximately 16, 8, 8 and 28 times for nicotine, acetaldehyde, PNC and PM 2.5 , respectively) compared to the levels resulting from conventional cigarette (CC) smoking under identical conditions. The maximum 30 min concentration of PNC (4.8 × 105 #/cm3), as well as maximum concentration of PNC (9.3 × 106 #/cm3) suggest that the intensive use of THS in a confined space with limited ventilation might cause substantially elevated aerosol concentrations, although these particles appeared as highly volatile ones and evaporated within seconds. Generally, the usage intensity (number of simultaneous users) prevailed as the most important factor positively affecting pollutant variations; another important factor was the distance to bystander. Highlights • The impact of using tobacco heating system on indoor air was investigated. • The pollutant levels were significantly lower compared to conventional cigarettes. • Exhaled particles evaporated fast as opposed to those of conventional cigarettes. • Number of users was the most important factor affecting indoor air quality. [ABSTRACT FROM AUTHOR]

Intermediate volatile organic compounds (IVOCs) have recently been characterized for their contributions to the formation of secondary organic aerosol in atmospheric air. However, IVOCs in air in various indoor environments have not been characterized yet. In this study, we characterized and measured IVOCs, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), in residential indoor air in Ottawa, Canada. IVOCs, including n-alkanes, branched-chain alkanes (b-alkanes), unspecified complex mixtures (UCM) IVOCs, and oxygenated IVOCs (such as fatty acids), were found to have a large impact on indoor air quality. The results indicate that the indoor IVOCs behave differently from those in the outdoor environment. IVOCs in the studied residential air ranged from 14.4 to 69.0 μg/m3, with a geometric mean of 31.3 μg/m3, accounting for approximately 20% of the total organic compounds (IVOCs, VOCs and SVOCs) in indoor air. The total b-alkanes and UCM-IVOCs were found to have statistically significant positive correlations with indoor temperature but have no correlations with airborne particulate matter less than 2.5 μm (PM 2.5) as well as ozone (O 3) concentration. However, indoor oxygenated IVOCs behaved differently from b-alkanes and UCM-IVOCs, with a statistically significant positive correlation with indoor relative humidity but no correlation with other indoor environmental conditions. [Display omitted] • Intermediate volatile organic compounds (IVOCs) were characterized and measured in residential air. • Indoor IVOCs account for about 20% of the total organic compounds in the residential indoor air. • Indoor IVOCs behave differently from those in the outdoor environment. • Indoor temperature and humidity have a positive correlation with indoor IVOCs. • Indoor IVOCs identified may impact on the indoor air quality. [ABSTRACT FROM AUTHOR]

In response to the global impact of the COVID-19 pandemic, international and national authorities, including those in Catalonia (Spain), recognized the crucial need to ensure proper ventilation in classrooms, emphasizing the importance of safe and healthy indoor environments for face-to-face learning. The present work, conducted within the COVID-19 Sentinel Schools Network of Catalonia (CSSNC) framework, aimed to monitor carbon dioxide (CO 2) and nitrogen dioxide (NO 2) concentrations in 23 schools, ensuring a comprehensive sample regarding educational levels, daily scholar schedules, and classroom typologies distributed across the four provinces of Catalonia. The research spanned three study periods: March and April 2021, October 2021 to January 2022, and March to June 2022. Briefly, 28%, 25%, and 37% of classrooms surpassed the 700 parts per million (ppm) CO 2 limit in each study period, respectively. Generally, CO 2 averages were lower in preschool classrooms (mean ± SD = 486 ± 106 ppm), while high school classrooms displayed the highest CO 2 concentrations (mean ± SD = 710 ± 253 ppm). Moreover, classrooms in towns (<30000 inhabitants) exhibited higher CO 2 levels as compared to classrooms from schools located in cities. As for NO 2 , the highest averages were obtained in urban areas, particularly in the Barcelona metropolitan area (e.g. mean indoor levels of 24.56 μg m−3 as compared to 11.05 μg m−3 in towns). In addition, the Indoor/Outdoor ratio (I/O ratio) in towns was the lowest (0.60). These results, together with the higher concentration of CO 2 indoors, could indicate poorer ventilation in town schools. The results of this study are anticipated to contribute to implementing evidence-based measures to improve indoor air quality (IAQ) in educational settings. [Display omitted] • The COVID-19 pandemic raised significant concerns about indoor air quality. • This study monitored CO 2 and NO 2 levels in 23 schools. • CO 2 was measured with NDIR sensors and NO 2 with Palmes diffusion tubes. • Classrooms exceeded the 700 ppm CO 2 limit, though levels improved from pre-COVID. • The highest NO 2 levels were obtained in urban areas. [ABSTRACT FROM AUTHOR]

Ambient air pollution is a public health issue which could potentially exacerbate pre-existing respiratory conditions and contribute to increases in asthma incidence. This study aims to address gaps in understanding how IAQ is impacted by outdoor air quality, which was done by sampling for indoor gaseous and particulate pollutants in residence and facilities near the sources of pollution. The study areas were selected due to non-attainment status with air quality standards, as well as demographic and socioeconomic status of those residing in these areas. Samples are obtained from five locations around the study areas. The sampling procedure involves active sampling methodologies for particulate matter (PM) and gases. Average volatile organic compounds (VOC) levels of 2.71 ppm were measured at a location, while the average particulate matter (PM) concentrations in three study locations were; 15,979 pt/cc, 9533 pt/cc, 5267 pt/cc respectively, which exceeded clean background environment level of 500–2000 pt/cc. All locations had average CO concentrations above 0.3 ppm, which is potentially associated with elevated asthma symptoms. Results demonstrated that facilities in the study area have increased levels of indoor air pollutants that potentially increase asthma and respiratory issues. The study concludes that particulate and gaseous pollutant levels in the study areas are a concerning human health issue. The study outcomes have significant implications for air quality exposure modeling and potential exposure mitigation strategies, which are expected to facilitate the implementation of public policies for improved human health conditions. [ABSTRACT FROM AUTHOR]

Abstract This work was aimed at studying particulate matter (PM) in the indoor atmosphere of two flats where airtight biomass systems were used for domestic heating. PM 10 and PM 2.5 samples were collected by means of nine parallel sampling units, located in the outdoor and indoor areas of each flat. The samples were analyzed for PM macro-components (organic carbon, elemental carbon, macro-elements and inorganic ions) and for the soluble and residual fractions of micro-elements; the influence of the main PM sources on the indoor air quality was evaluated. The results confirm that infiltration from outdoor represents the main source of fine particles, while dust re-suspension, enhanced by the movements of the inhabitants, is one of the most important sources of coarse particles. Biomass-fueled heating systems are a significant source of indoor pollution, mainly due to the cleaning operations required for the removal of residual ash, which release particles in both the fine and the coarse size range. The impact of these operations resulted in indoor to outdoor ratios higher than one for most of the considered PM components. Very high amounts of copper and manganese, elements likely involved in the generation of oxidative stress, were released into the environment during ash removal from the pellet stove. Although this operation was very limited in time (about 15 min), the average concentration of Cu and Mn in PM 10 and PM 2.5 during the study period (18 days) was more than six times (Cu) and about twice (Mn) the concentration values measured outdoors. Graphical abstract Image 1 Highlights • We studied the influence of airtight wood-fired appliances on indoor air quality. • Biomass-fueled heating systems are a significant source of indoor PM. • Removal of residual ash releases particles in both the fine and the coarse size range. • Very high concentration of Mn and Cu were measured in indoor air. • Possible health effects of this indoor pollution source merits further understanding. [ABSTRACT FROM AUTHOR]

This study explored the toxic gas detection using a set of two spark-induced plasma emission spectroscopy (SIPS) modules as an alternative to conventional chemical sensors. This opens up a new possibility for detecting toxic molecules (formaldehyde, acetaldehyde, acetic acid, toluene, and ammonia) in real-time (<3 s) at relatively high sensitivity (<5 ppm). An optimized electrical controller (Raspberry Pi), manufactured as a compact and economical 3-channel optical measuring device, was developed for handling the high-resolution time-resolved electrical signals from the plasma emissions. Subsequently, the findings of this research elucidate the usability of the 3-channel SIPS device for quantitative monitoring of toxic gases. [Display omitted] • Toxic gas detection via SIPS is performed for the first time. • 3-channel SIPS device is designed for detecting molecular bands. • Fast (<3 s) and accurate (<5 ppm) quantitative gas monitoring is achieved. [ABSTRACT FROM AUTHOR]

The present study examines indoor air pollution in health facilities, focusing on compounds from various sources, such as industrial products, healthcare activities and building materials. It assesses chemical and microbiological concentrations in two public hospitals, two public healthcare centres, and one public health laboratory in Spain. Measurements included indoor air quality, microbiological contaminants, ambient parameters and non-target analysis across ten different locations. Outdoor air quality was also assessed in the surroundings of the hospitals. The results showed that around 350 substances were tentatively identified at a high confidence level, with over 50 % of compounds classified as of high toxicological risk. Three indoor and 26 outdoor compounds were fully confirmed with standards. These confirmed substances were linked to medical, industrial and agricultural activities. Indoor Air Quality (IAQ) results revealed that CO, CO 2 , formaldehyde (HCHO), O 3 and total volatile organic compounds (TVOCs) showed average values above the recommended guideline levels in at least one of the evaluated locations. Moreover, maximum concentrations detected for CO, HCHO, O 3 and TVOCs in hospitals surpassed those previously reported in the literature. SARS-CoV-2 was detected in three air environments, corresponding to COVID-19 patient areas. Fungi and bacteria concentrations were acceptable in all assessed locations, identifying different fungi genera, such as Penicillium , Cladosporium , Aspergillus , Alternaria and Botrytis. [Display omitted] • For the first time, pollutants surrounding healthcare facilities were studied. • More than 350 substances were detected using non-target strategies. • 26 substances were confirmed in outdoor and indoor air using analytical standards. • Some pollutants in indoor air revealed average values above guideline values. • SARS-CoV-2 was detected in the air in COVID-19 patient environments. [ABSTRACT FROM AUTHOR]

With the introduction of novel and potentially less polluting nicotine containing products to the market, the impacts of their usage to indoor air quality as opposed to conventional pollution sources must be reviewed and considered. This review study aimed to comparatively analyse changes in indoor air quality as the consequence of tobacco heating system (THS) generated pollution against general indoor air quality in various micro-environments, especially with combustion-based pollution sources present. Indoor concentrations of formaldehyde, acetaldehyde, benzene, toluene, nicotine and PM 2.5 were reviewed and compared; concentrations of other harmful and potentially harmful substances (HPHCs) were discussed. Generally, the usage of THS has been associated with lower or comparable indoor air pollutant concentrations compared against other conventional indoor sources or environments, in most cases distinguishable above background, thus potentially being associated with health effects at prolonged exposures as any other artificial air pollution source. In the controlled environment the use of THS (as well as an electronic cigarette) resulted in the lowest concentrations of formaldehyde, benzene, toluene, PM 2.5, among majority researched pollution sources (conventional cigarettes, waterpipe, incense, mosquito coils). The exposure to significantly higher pollution levels of benzene, toluene, and formaldehyde occurred in public environments, especially transport micro-environments. Such low levels of conventionally-assessed indoor pollutants resulting from the use of new nicotine containing products raise challenges for epidemiological studies of second-hand exposure to THS aerosol in real-life environments. [ABSTRACT FROM AUTHOR]

In recent years, the use of kerosene space heaters as additional or principal heat source has been increasing, because these heaters allow a continuous control on the energy cost. These devices are unvented, and all combustion products are released into the room where the heaters are operated. The indoor air quality of seven private homes using wick-type or electronic injection-type kerosene space heaters was investigated. Concentrations of CO, CO 2 , NO x , formaldehyde and particulate matter (0.02–10 μm) were measured, using time-resolved instruments when available. All heaters tested are significant sources of submicron particles, NO x and CO 2 . The average NO 2 and CO 2 concentrations are determined by the duration of use of the kerosene heaters. These results stress the need to regulate the use of unvented combustion appliances to decrease the exposure of people to air contaminants. [ABSTRACT FROM AUTHOR]

Abstract: The importance of good indoor air quality for the health of the individual was recognized as long as 150years ago and that period also saw recommendations, which essentially related to questions of ventilation and carbon dioxide. The first evaluation standards for organic and inorganic substances were laid down in the 1970s, often on an empirical basis. It was in the mid-1980s of the 20th century that a shift occurred towards systematically evaluating the results of indoor air measurements, carrying out representative environmental surveys and deriving guideline values and reference values on the basis of toxicological, epidemiological and statistical criteria. Generally speaking the indoor environment is an area which can only be assessed with difficulty since its occupants are in most cases exposed to mixtures of substances and there can be great local and temporal variations in the substance spectrum. Data are available today for a large number of substances and this makes it possible, with the aid of statistically derived reference values and toxicologically based guideline values, to make useful recommendations regarding good indoor air quality. Nevertheless, it is still difficult to evaluate reactive compounds and reaction products. What is disadvantageous, however, is the fact that different guideline values may be published for one and the same substance, whose justification and area of application are often not transparent. A guideline or reference value can only be regarded as rational when necessary and when a strategy for its verification is available. [Copyright &y& Elsevier]

The concentrations of respirable particulate matter (PM) and the impact on indoor air quality in occupational settings remains poorly characterized. This study assesses, for the first time, the cumulative and non-cumulative concentrations of 14 fractions of coarse (3.65–9.88 μm), fine (0.156–2.47 μm), and ultrafine (0.015–0.095 μm) PM inside the garage of heavy vehicles, firefighting personal protective equipment' storage room, bar, and a common area of seven Portuguese fire stations. Sampling campaigns were performed during a regular work week at the fire stations. Levels of daily total cumulative PM ranged from 277.4 to 413.2 μg/m3 (maximum values of 811.4 μg/m3), with the bar (370.1 μg/m3) and the PPE' storage room (361.3 μg/m3) presenting slightly increased levels (p > 0.05) than the common area (324.8 μg/m3) and the garage (339.4 μg/m3). The location of the sampling site, the proximity to local industries and commercial activities, the layout of the building, the heating system used, and indoor sources influenced the PM concentrations. Fine (193.8–301.0 μg/m3) and ultrafine (41.3–78.2 μg/m3) particles were predominant in the microenvironments of all fire stations and accounted for 71.5% and 17.8% of daily total cumulative levels, respectively; coarse particles (23.3–47.1 μg/m3) represented 10.7% of total PM. The permissible exposure limit (5.0 mg/m3) defined by the Occupational Safety and Health Organization for respirable dust was not overcome in the evaluated fire stations. Results suggest firefighters' regular exposure to fine and ultrafine PM inside fire stations which will contribute to cardiorespiratory health burden. Further studies are needed to characterize firefighters' exposure to fine and ultrafine PM inside fire stations, identify main emission sources, and evaluate the contribution of exposures at fire stations to firefighters' occupational health risks. [Display omitted] • Coarse, fine and ultrafine PM were for the first time assessed at fire stations. • Location, building layout, indoor sources and heating systems impacted PM levels. • The bar and the PPE' storage room presented the highest levels of respirable PM. • Fine and ultrafine PM were the predominant fractions in all microenvironments. • OSHA guidelines were not exceeded in fire stations. [ABSTRACT FROM AUTHOR]

Indoor air quality has become a growing concern due to the increasing proportion of time people spend indoors, combined with reduced building ventilation rates resulting from an increasing awareness of building energy use. It has been well established that potted-plants can help to phytoremediate a diverse range of indoor air pollutants. In particular, a substantial body of literature has demonstrated the ability of the potted-plant system to remove volatile organic compounds (VOCs) from indoor air. These findings have largely originated from laboratory scale chamber experiments, with several studies drawing different conclusions regarding the primary VOC removal mechanism, and removal efficiencies. Advancements in indoor air phytoremediation technology, notably active botanical biofilters, can more effectively reduce the concentrations of multiple indoor air pollutants through the action of active airflow through a plant growing medium, along with vertically aligned plants which achieve a high leaf area density per unit of floor space. Despite variable system designs, systems available have clear potential to assist or replace existing mechanical ventilation systems for indoor air pollutant removal. Further research is needed to develop, test and confirm their effectiveness and safety before they can be functionally integrated in the broader built environment. The current article reviews the current state of active air phytoremediation technology, discusses the available botanical biofiltration systems, and identifies areas in need of development. [ABSTRACT FROM AUTHOR]

Highlights: [•] Wood-burning fireplaces are potential sources of indoor air contaminants. [•] Especially the concentration of ultrafine particles increases during operation. [•] The effects of NO x , CO and CO2 were comparatively small. [•] In addition to the combustion process itself firelighters are a potential source for benzene. [•] In some case increased concentrations of benzo[a]pyrene were measured. [ABSTRACT FROM AUTHOR]

Urban residential and industrial growth development affects sustainable and healthful indoor environments. Environmental issues are a global problem. The deterioration of indoor air quality has prompted the creation of several air cleansing techniques. This review explains how carbon-based materials have influenced the development of air purification systems using photocatalysis. These carbon-based materials offer unique properties and advantages in VOC removal processes. Biochar, produced from biomass pyrolysis, provides an environmentally sustainable solution with its porous structure and carbon-rich composition. Carbon quantum dots, with their quantum confinement effects and tunable surface properties, show promise in VOC sensing and removal applications. Polymers incorporating reduced graphene oxide demonstrate enhanced adsorption capabilities owing to the synergistic effects of graphene and polymer matrices. Activated carbon fibers, characterized by their high aspect ratio and interconnected porosity, provide efficient VOC removal with rapid kinetics. With their unique electronic and structural properties, graphitic carbon nitrides offer opportunities for photocatalytic degradation of VOCs under visible light. Catalysts integrated with MXene, a two-dimensional nanomaterial, exhibit enhanced catalytic activity for VOC oxidation reactions. Using various carbon-based materials in VOC removal showcases the versatility and effectiveness of carbon-based approaches in addressing environmental challenges associated with indoor air pollution. Metal-organic-framework materials are carbon-based compounds. It examines the correlation between VOC mineralization and specific characteristics of carbon materials, including surface area, adsorption capability, surface functional groups, and optoelectronic properties. Discussions include the basics of PCO, variables influencing how well catalysts degrade, and degradation mechanisms. It explores how technology will improve in the future to advance studies on healthy and sustainable indoor air quality. [Display omitted] • Carbon foam, surface functionalization as promising material were reviewed. • VOCs (volatile organic compounds and their environmental problems. • Efficient photocatalytic remediation of VOCs pollutants on composite surface was discussed. • Comprehensive conclusion and future prospectives were also reported. [ABSTRACT FROM AUTHOR]

Chemical emissions from two new memory foam mattresses were evaluated in a simulated consumer use environment over the course of 32 days. Passive 12- and 24-h samples (n = 62) were collected for various VOCs. Airborne concentrations of chemicals associated with the mattresses (2-propanol, acetone, chloromethane, toluene, and ΣVOC) peaked during the first day after installation and progressively decayed over the course of the following 31 days. Emission rates were derived using a two-phase, double exponential source decay model paired with a one-compartment generalized indoor air quality model; short- and long-term emission half-lives for individual chemicals were on the order of hours (approximately 4 or 12 h) and days (approximately 24 days), respectively. Model-estimated average ΣVOC concentrations for the 32-day period of the study were approximately 20 and 33 μg/m3 for Mattress 1 and 2, respectively, while the modeled one-year average concentrations were 2.7 and 4.2 μg/m3, respectively. First-year trends for both mattresses were qualitatively similar, with the sum of 2-propanol, acetone, chloromethane, and toluene contributing to approximately 81% and 95% of the first-year ΣVOC concentration of Mattress 1 and 2, respectively. The airborne concentrations of individual chemicals and ΣVOC measured and modeled in this study were well below available health-based benchmarks for individual chemicals and within available indoor air quality recommendations for ΣVOC, suggesting that it is unlikely that the use of the models of mattresses evaluated in this study would pose a health risk to consumers. [Display omitted] • Chemical emissions may occur during consumer use of memory foam mattresses. • Chemical emissions peak within a day after installation and decay thereafter. • Model-estimated chemical concentrations are below existing exposure benchmarks. • Use of the memory foam mattresses tested in this study are unlikely to pose a health risk to consumers. [ABSTRACT FROM AUTHOR]

Indoor air pollution resulting from volatile organic compounds (VOCs) is a significant health concern, especially formaldehyde. Therefore, predicting indoor formaldehyde concentration is essential for environmental control. In this research, the authors develop a thermal and wet coupling calculation model of porous fabric that considers the influence of different phases of wet components and the coupling effect of heat and humidity on formaldehyde migration. We propose a modified calculation method of the formaldehyde mass transfer characteristic parameters of fabric to obtain the diffusion coefficient D and partition coefficient K. The heat and humidity coupling model and formaldehyde mass transfer model of fabric are simultaneously solved, and the authors analyze the influence mechanism of fabric loading rate, fabric type, temperature, and humidity on indoor formaldehyde mass transfer characteristics. We study the variation trend of fabric formaldehyde mass transfer characteristics coefficient and the temporal and spatial distribution of indoor formaldehyde concentration. The theoretical model is applied to practical problems by pre-evaluating the indoor formaldehyde concentration of decorated residential buildings in typical climate areas of China before occupancy. The authors obtain the variation rule of indoor formaldehyde concentration of residential buildings under typical hot and humid climate conditions, building materials, furniture, and fabrics. To provide theoretical support for indoor environmental control and human health protection. [Display omitted] • The VOC mass transfer process and heat and moisture transfer process of fabric are considered in coupling. • The influence of different phases of wet components is considered on VOC migration. • A calculation method for fabric's VOC mass transfer characteristic parameters is proposed. • The influence mechanism of fabric loading rate, fabric type, temperature, and humidity on indoor VOC migration are analyzed. [ABSTRACT FROM AUTHOR]

The study investigates the impact of sampling method on the concentrations of PBDEs (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, and BDE-209) and NBFRs (PBEB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) in indoor dust. A total of 36 dust samples were collected from 12 homes in Birmingham, UK (3 samples per home comprising researcher collected dust – both RCD from the living room (RCDL) and bedroom (RCDB), with an additional householder vacuum dust sample - HHVD). BDE-209 was the predominant compound, with average concentrations of 2642, 2336 and 2634 ng/g in RCDL, RCDB and HHVD respectively. The next most abundant BFR was BEH-TEBP, followed by DBDPE, with average concentrations of 306, 339 and 233 ng/g for BEH-TEBP and 155, 91 and 152 ng/g for DBDPE in RCDL, RCDB and HHVD respectively. Average concentrations of Σ 6 tri-hexa-BDEs were 47, 41, and 24 ng/g in RCDL, RCDB and HHVD respectively. With the exception of Σ 6 tri-hexa-BDEs, BDE-153, BDE-99 and to some extent BEH-TEBP, no significant differences were found between BFR concentrations in RCD and HHVD. Statistically significant correlations were observed between concentrations of Σ 6 tri-hexa-BDEs, BEH-TEBP and DBDPE in HHVD and in both RCDL and RCDB. However, comparison of estimates of exposure via dust ingestion based on these two sampling methods revealed that using householder vacuum dust underestimates exposure, particularly for Σ 6 tri-hexa-BDEs, and to some extent for BEH-TEBP. In contrast, HHVD could be a viable alternative to RCD as a metric of exposure for higher brominated BFRs. [ABSTRACT FROM AUTHOR]

Abstract: Indoor air concentrations of volatile organic compounds often exceed outdoor levels by a factor of 5. There is much interest in developing new technologies in order to improve indoor air quality. In this work non-thermal plasma (DC positive corona discharge) is explored as an innovative technology for indoor air purification. An inlet gas stream of 10lmin−1 containing 0.50±0.02ppm toluene was treated by the plasma reactor in atmospheric conditions. Toluene removal proved to be achievable with a characteristic energy density ε 0 of 50Jl−1. Removal efficiencies were higher for 26% relative humidity (ε 0 =35Jl−1), compared with those at increased humidities (50% relative humidity, ε 0 =49Jl−1). Reaction products such as formic acid, benzaldehyde, benzyl alcohol, 3-methyl-4-nitrophenol, 4-methyl-2-nitrophenol, 4-methyl-2-propyl furan, 5-methyl-2-nitrophenol, 4-nitrophenol, 2-methyl-4,6-dinitrophenol are identified by means of mass spectrometry. Based on these by-products a toluene degradation mechanism is proposed. [Copyright &y& Elsevier]

Nowadays, people spend 80–90% of their time indoors, while recent policies on energy efficient and safe buildings require reduced building ventilation rates and locked windows. These facts have raised a growing concern on indoor air quality, which is currently receiving even more attention than outdoors pollution. Prevention is the first and most cost-effective strategy to improve indoor air quality, but once pollution is generated, a battery of physicochemical technologies is typically implemented to improve air quality with a questionable efficiency and at high operating costs. Biotechnologies have emerged as promising alternatives to abate indoor air pollutants, but current bioreactor configurations and the low concentrations of indoor air pollutants limit their widespread implementation in homes, offices and public buildings. In this context, recent investigations have shown that potted plants can aid in the removal of a wide range of indoor air pollutants, especially volatile organic compounds (VOCs), and can be engineered in aesthetically attractive configurations. The original investigations conducted by NASA, along with recent advances in technology and design, have resulted in a new generation of botanical biofilters with the potential to effectively mitigate indoor air pollution, with increasing public aesthetics acceptance. This article presents a review of the research on active botanical filters as sustainable alternatives to purify indoor air. [Display omitted] • Indoor air pollution is associated with detrimental public health problems. • Active botanical filters are an effective biotechnology for indoor air purification. • NASA initially proposed botanical systems to cope with indoor air pollutants. • Well-designed botanical filters effectively purify indoor air at low operating cost. [ABSTRACT FROM AUTHOR]

Indoor air pollution is a serious health problem throughout the world. Plants are known to be able to reduce the effect of air pollution and improve indoor air quality (IAQ). The aim of the present study was to compare the effectiveness of four plant species (Tradescantia zebrina hort. ex Bosse, Philodendron scandens K. Koch & Sello, Ficus pumila L. and Chlorophtytum comosum (Thunb.) Jacques) planted in an active living wall (ALW) for capturing particle pollutants. The ALW was introduced in a glass chamber and exposed to large (10–40 μm) and fine (1.2–10 μm) airborne particles containing a fixed concentration of potentially toxic elements (Al, B, Cd, Co, Cr, Cu, Ni and Pb). The surface particle deposition (sPM) was estimated in the leaves from the four species and the potentially toxic element concentration in the particulate matter (PM) was measured in plants, medium culture and in the ALW support system. The distribution of different particle size fractions differed between species. The capacity to trap particles on leaf surfaces was similar among the species (4.7–13 ng cm−2) except when comparing Tradescantia and Chlorophytum with Ficus , being higher in the latter species. Differences in toxic elements accumulation capacity were observed between species depending on the elements considered. The percentage of reduction in indoor pollution using an ALW was in a range of 65–79% being similar between species. Plants were the most important component of the ALW in terms of accumulation of indoor potentially toxic elements. The data presented here could be used to model the effectiveness of ALW systems schemes in improving IAQ. [Display omitted] [ABSTRACT FROM AUTHOR]

Seven types of indoor samples, covering five indoor matrices, were collected in a residential room, and analyzed for five classes of semivolatile organic compounds (SVOCs). The goal was to improve the understanding of the relationship between indoor air, surface films and dust, based on differences in sources, physicochemical properties, and indoor environmental characteristics. Comparisons of the five matrices (gas- and particle-phase air, floor dust, surface dust/films and window films) demonstrated that within our test room a semi-quantitative measurement of the SVOC distributions and concentrations could be obtained by air, and composite dust or furniture surface wipes. Dust concentrations varied within the room, and spot samples were not necessarily representative of the average room conditions. Polyurethane foam passive air samplers (PUF-PAS) successfully quantified the total air concentrations of the studied SVOC compound groups, as indoor air concentrations were dominated by gas-phase compounds, however air concentrations of individual particle-bound compounds had higher uncertainty. Measured concentrations of dust/surfaces could be used to estimate air concentrations of legacy SVOCs, demonstrating equilibrium in the room. However, air concentrations of current-use compounds (flame retardants, polycyclic aromatic hydrocarbons (PAHs)) could not be estimated from dust/surface concentrations, demonstrating the influence of ongoing primary emissions and non-equilibrium status in the room. [ABSTRACT FROM AUTHOR]

Indoor air pollution has traditionally received less attention than outdoors pollution despite indoors pollutant levels are typically twice higher, and people spend 80–90% of their life in increasing air-tight buildings. More than 5 million people die every year prematurely from illnesses attributable to poor indoor air quality, which also causes multi-millionaire losses due to reduced employee's productivity, material damages and increased health system expenses. Indoor air pollutants include particulate matter, biological pollutants and over 400 different chemical organic and inorganic compounds, whose concentrations are governed by several outdoor and indoor factors. Prevention of pollutant is not always technically feasible, so the implementation of cost-effective active abatement units is required. Up to date no single physical-chemical technology is capable of coping with all indoor air pollutants in a cost-effective manner. This problem requires the use of sequential technology configurations at the expenses of superior capital and operating costs. In addition, the performance of conventional physical-chemical technologies is still limited by the low concentrations, the diversity and the variability of pollutants in indoor environments. In this context, biotechnologies have emerged as a cost-effective and sustainable platform capable of coping with these limitations based on the biocatalytic action of plants, bacteria, fungi and microalgae. Indeed, biological-based purification systems can improve the energy efficiency of buildings, while providing additional aesthetic and psychological benefits. This review critically assessed the state-of-the-art of the indoor air pollution problem and prevention strategies, along with the recent advances in physical-chemical and biological technologies for indoor pollutants abatement. • A state-of-the-art review on the global problem of poor indoor air quality. • Typology, sources and health risks of the most common indoor pollutants are revised. • Measures for prevention and abatement of indoor pollutants are carefully examined. • Evaluation of the performance of traditional physical-chemical methods. • Assessment of innovative and sustainable systems based on biotechnologies. [ABSTRACT FROM AUTHOR]

The level of carbonyl compounds in indoor air is crucial due to possible health effects and the high prevalence of their potential sources. Therefore, selecting a convenient and rapid analytical technique for the reliable detection of carbonyl compound concentrations is important. The acetyl acetone (acac) method is a widely used standard procedure for detecting gaseous formaldehyde. For measuring formaldehyde along with other carbonyl compounds, the DNPH-method is commonly applied. The recommended procedure for measuring volatile organic compounds (VOCs) is sampling on Tenax TA, followed by thermal desorption and GC/MS analysis. In this study, different analytical techniques for the quantification of formaldehyde, pentanal, and hexanal are critically compared. It was found that the acac- and DNPH-method are in very good agreement for formaldehyde. In contrast, the DNPH-method significantly underestimates indoor air concentrations of the higher aldehydes in comparison to sampling on Tenax TA, although both methods are strongly correlated. The reported results are part of the EURIMA-WKI study on levels of indoor air pollutants resulting from construction, building materials and interior decoration. [Copyright &y& Elsevier]

Materials Institute Lavoisier (MIL) metal organic frameworks (MOFs) are known for their potential to adsorb gaseous organic pollutants. This study explores the synergistic effects between the selection of central metals (e.g., titanium, iron, and aluminum) and the incorporation of –NH 2 groups in terms of adsorption efficiency against gaseous formaldehyde (FA). A group of the pristine MIL MOFs is synthesized using three different metals (i.e., titanium, iron, and aluminum) and terephthalic acid along with their NH 2 derivatives using 2-aminoterephthalic acid. Among the pristine forms, MIL-125(Ti) achieves the highest FA adsorption capacity (Q) of 26.96 mg g−1 and a partition coefficient (PC) of 0.0898 mol kg−1 Pa−1. Further, amination significantly improves the FA adsorption potential of NH 2 -MIL-125(Ti) with a Q value of 91.22 mg g−1 (PC = 0.3038 mol kg−1 Pa−1). In situ diffuse reflectance infrared Fourier-transform spectroscopy reveals that the FA adsorption of plain MILs should be governed primarily by physisorption. In contrast, FA adsorption of NH 2 -MILs appears to be regulated by both physisorption and chemisorption, while the latter being affected mainly through FA-NH 2 interactions (Schiff base reactions). These findings provide valuable insights into the utility of aminated MIL sorbents, possibly toward the efficient management of indoor air quality. [Display omitted] • MIL MOFs with different central metals and organic ligands were formulated. • Effects of key variables (e.g., formaldehyde concentration and relative humidity) on MIL adsorption were studied. • NH 2 -MIL-125(Ti) was identified as the best performer for FA adsorption. • Chemisorption dominated FA adsorption on aminated MIL MOFs through a Schiff base reaction. [ABSTRACT FROM AUTHOR]

Chemical reaction and physical transport characteristics of indoor surfaces play an important role in indoor air quality. This study presents a kinetic model to describe the reaction of ozone with squalene on indoor surfaces in a family house, by incorporating external and internal mass transfer, surface partitioning, and chemical reaction on indoor surfaces. Field experiments were performed in the family house. The first 3-days of data, collected when the house was unoccupied, are used to derive the key parameters in the model, which are then used for predicting the concentrations in other unoccupied days. Comparison of squalene oxidation products during the occupied and unoccupied periods shows that even if the house is unoccupied for several days, the indoor concentrations of 6-methyl-5-hepten-2-one (6-MHO) and 4-oxopentanal (4-OPA) remain substantial, demonstrating that surface reaction of ozone with off-body squalene can significantly impact the composition of indoor air. Model predictions of the three compounds (ozone, 6-MHO, and 4-OPA) agree well with the experimental observations for all test days. Furthermore, we make the first attempt to estimate the duration of typical polyunsaturated aldehydes (TOP, TOT, and TTT), which indicated that these compounds, as well as off-body squalene, can persist on indoor surfaces for a relatively long period in the examined residence. [Display omitted] • A model is developed to describe the ozone/squalene reaction on indoor surfaces. • The kinetic model comprehensively considers chemical reaction and physical process. • Field campaign was conducted in a family house under occupied and unoccupied period. • The effectiveness of the model is validated by the PTR-TOF-MS measured data. • The duration of TOP, TOT, and TTT on indoor surface is estimated for the first time. [ABSTRACT FROM AUTHOR]

Mold contamination is one of the most important causes for indoor air pollution. Previous studies have indicated the feasibility of employing wet-dry cycles, a special water treatment approach in indoor environments, to control indoor mold contamination. However, the underlying mechanisms regulating the responses of indoor molds to changing moisture conditions remains to be elucidated. Here, we studied the mechanisms regulating the responses to wet-dry cycles (termed as moisture dynamics) in Aspergillus penicillioides , Cladosporium cladosporioides , and Aspergillus niger. First, the dormant spores of each mold species were grown to the swollen stage. Next, swollen spores were incubated at different water activity (a w) levels (0.4, 0.6 and 0.8 a w) for up to 15 days. Afterward, the viability, lipid peroxidation and antioxidant activities (both enzymatic and non-enzymatic) of treated molds were determined. Our results show that the mold species that survived better under moisture dynamics also encountered less oxidative damage and exhibited stronger antioxidant activities. Moreover, lower RH imposed severer oxidative stress to C. cladosporioides and A. niger. Pearson correlation coefficient indicate significant correlations between oxidative stress and a w of dry periods, oxidative damage and mold survival, as well as oxidative responses and mold survival. Collectively, these results imply that oxidative stress adaptation regulates the viability of A. penicillioides , C. cladosporioides , and A. niger in response to moisture dynamics. Our findings facilitate the development of novel engineering solutions for indoor air pollution. [Display omitted] • Indoor molds are pungent contaminants that deteriorate indoor air quality. • Oxidative stress adaptation is crucial for indoor mold survival under moisture dynamics. • Antioxidant responses may be used as targets to improve indoor air quality. [ABSTRACT FROM AUTHOR]

Carbon adsorbents have been widely used to remove indoor volatile organic compounds (VOCs), however, the proliferation of bacteria on the carbon adsorbents may deteriorate the indoor air quality and thus pose a serious threat to human health. Herein, we report the synthesis of antibacterial porous carbon spheres (carbonized aminophenol-formaldehyde resin, CAF) with well-dispersed Cu species via an in situ incorporation of Cu2+ during the polymerization of 3-aminophenol-formaldehyde resin followed by a thermal carbonization and reduction process. Compared with CAF, the Cu/CAF- x nanocomposites with Cu loading show a much higher specific surface area (>700 m2 g−1 vs. 569 m2 g−1 for CAF). In addition, the pore size of Cu/CAF- x is ranging from 0.7 to 1.68 nm, which is exactly conducive to adsorb the toluene molecules. As a result, the toluene adsorption capacity is improved from 123.50 mg g−1 for CAF to >170 mg g−1 for Cu/CAF- x. More importantly, such adsorbents possess excellent antibacterial performance, the Cu/CAF-10 (10 wt% of Cu loading) with a concentration of 50 μg mL−1 can completely kill the E. coli within 30 min. Our work paves the way to the development of bifunctional adsorbents with both efficient VOCs adsorption and excellent antibacterial performance. [Display omitted] • An in situ complexation strategy is developed to prepare Cu loaded carbon composite. • Cu/CAF- x show higher toluene adsorption capacity than porous carbon adsorbent. • Cu/CAF-10 with a low concentration of 50 μg mL-1 can kill 100% E. coli within 30 min. • The in situ complexation strategy can be extended to prepare other metal-carbon composites. [ABSTRACT FROM AUTHOR]

Abstract Fifteen polycyclic aromatic hydrocarbons (PAHs) were measured in the spider webs prepared in the laboratory and exposed to indoor air pollution in a defined period of time. We have selected homes differing in location (rural area vs. city), type of room (living room, kitchen, basement), inhabitants' habits (smoking cigarettes vs. non-smoking) and type of heating/cooking devices used (natural gas, liquefied gas, coal- and wood-fuelled heating). Webs from two species, from Agelenidae and Pholcidae families, were prepared and used for monitoring of PAHs. PAHs were characterised based on concentration, profile distribution, source apportionment by cluster analysis and diagnostic ratios. The concentrations of sum of 15 PAHs (μg g−1 dry weight) varied from 1.7 (bedroom in detached house in rural area) to 67.9 μg g−1 (room with heavy smokers in detached house in the city), and were dominated by 3-ring (6.89–57.1%) and 2-ring compounds (5.05–48.3%). The result of cluster analysis (CA) suggested two distinct groups of PAHs. The dominant PAH source was found to be mixed petrogenic and pyrogenic consisting of a mixture of cooking, smoking, heating and neighbouring traffic activities. Graphical abstract Image 1 Highlights • Indoor PAH monitoring using spider webs has been conducted for the first time. • Differences in PAH content of spider webs from various indoor environments are evident. • PAH concentration and PAH profile in indoor spider webs are related to their origin. [ABSTRACT FROM AUTHOR]

Exposure to particulate emissions poses a variety of public health concerns worldwide, specifically in developing countries. This review summarized the documented studies on indoor particulate matter (PM) emissions and their major health concerns in South Asia. Reviewed literature illustrated the alarming levels of indoor air pollution (IAP) in India, Pakistan, Nepal, and Bangladesh, while Sri Lanka and Bhutan are confronted with relatively lower levels, albeit not safe. To our knowledge, data on this issue are absent from Afghanistan and Maldives. We found that the reported levels of PM 10 and PM 2.5 in Nepal, Pakistan, Bangladesh, and India were 2–65, 3–30, 4–22, 2–28 and 1–139, 2–180, 3–77, 1–40 fold higher than WHO standards for indoor PM 10 (50 μg/m 3 ) and PM 2.5 (25 μg/m 3 ), respectively. Regarding IAP-mediated health concerns, mortality rates and incidences of respiratory and non-respiratory diseases were increasing with alarming rates, specifically in India, Pakistan, Nepal, and Bangladesh. The major cause might be the reliance of approximately 80% population on conventional biomass burning in the region. Current review also highlighted the prospects of IAP reduction strategies, which in future can help to improve the status of indoor air quality and public health in South Asia. [ABSTRACT FROM AUTHOR]

The current study evaluated the technical feasibility of applying TiO2 photocatalysis to the removal of low-ppb concentrations of volatile organic compounds (VOCs) commonly associated with non-occupational indoor air quality issues. A series of experiments was conducted to evaluate five parameters (relative humidity (RH), hydraulic diameter (HD), feeding type (FT) for VOCs, photocatalytic oxidation (PCO) reactor material (RM), and inlet port size (IPS) of PCO reactor) in relation to the PCO destruction efficiencies of the selected target VOCs. None of the target VOCs exhibited any significant dependence on the RH, which is inconsistent with a previous study where, under conditions of low humidity and a ppm toluene inlet level, a drop in the PCO efficiency was reported with a decreasing humidity. However, the other four parameters (HD, RM, FT, and IPS) were found to be important for better VOC removal efficiencies as regards the application of TiO2 photocatalytic technology for cleansing non-occupational indoor air. The PCO destruction of VOCs at concentrations associated with non-occupational indoor air quality issues was up to nearly 100%, and the CO generated during PCO was a negligible addition to indoor CO levels. Accordingly, a PCO reactor would appear to be an important tool in the effort to improve non-occupational indoor air quality. [Copyright &y& Elsevier]

Abstract Characteristics of indoor volatile organic compounds (VOCs) and their health risks were investigated in kitchens and bedrooms during the heating season in rural Guanzhong Plain, China. Toxic-VOC concentrations in kitchens with traditional wood (299 ± 38.8 μg m−3) and liquefied petroleum gas (LPG) stoves (187 ± 54.6 μg m−3) were considerably higher than those in bedrooms. High levels of toxic VOCs in traditional kitchens were strongly correlated with wood combustion (R = 0.72). The coefficient of determination of VOC profiles between the kitchen and wood combustion was 0.27, indicating that VOCs in traditional kitchens are mainly derived from wood combustion. For women, who do most of the cooking, noncancer risk from exposure to toxic VOCs could reach 7600 and 2550 in traditional and LPG kitchens, respectively. Noncancer risks were much lower in bedrooms than in kitchens, but still two orders of magnitude higher than the United States Environmental Protection Agency (USEPA) threshold. Cancer risk from exposure to VOCs for women was 8.98 × 10−4 and 1.67 × 10−4 in both traditional and LPG kitchens, respectively, and ranged from 2.51 × 10−6 to 3.85 × 10−5 in bedrooms—all exceeding the USEPA threshold. Thus, during the heating season indicated that the rural Guanzhong residents were exposed to toxic VOCs from indoor heating and cooking at levels higher than the recommended safety levels. Moreover, traditional cooking and heating styles in rural Guanzhong need to be urgently updated to improve the indoor air quality for residents. Highlights • Profiles of toxic VOCs in 2 kitchens and 5 typical bedrooms were investigated. • Kitchen with tradition wood stove showed the highest toxic VOCs concentrations. • Cancer (noncancer) risk exposure to VOCs for women highly exceeded USEPA threshold. • Indoor toxic VOCs were demonstrated mostly derived from indoor solid-fuel burning. [ABSTRACT FROM AUTHOR]

Air cleaning technologies are needed to reduce indoor concentrations and exposure to volatile organic compounds (VOCs). Currently, air cleaning technologies lack an accepted test standard to evaluate their VOC removal performance. A protocol to evaluate the VOC removal performance of air cleaning devices was developed and piloted with two devices. This method injects a VOC mixture and carbon dioxide into a test chamber, supplies outdoor air at a standard building ventilation rate, periodically measures the VOC concentrations in the chamber using solid phase microextraction-gas chromatography-mass spectrometry over a 3-h decay period, and compares the decay rate of VOCs to carbon dioxide to measure the VOC removal air cleaning performance. The method was demonstrated with both a hydroxyl radical generator and an activated carbon air cleaner. It was shown that the activated carbon air cleaner device tested had a clean air delivery rate an order of magnitude greater than the hydroxyl radical generator device (72.10 vs 6.32 m3/h). [Display omitted] • Method to evaluate air cleaner volatile organic compound removal performance. • Clean air delivery rate for removal of volatile organic compounds. • CADR of carbon filter was eleven times the hydroxyl radical generator tested. [ABSTRACT FROM AUTHOR]

In addition to the biodegradation problems encountered in buildings, exposure of their occupants to mold is responsible for numerous diseases such as respiratory infections, immediate or delayed allergies and different types of irritations. However, current techniques are unable to detect mold at an early stage of development or hidden contaminants. Moularat et al., in 2008 has established chemical fingerprints of moldy growth from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism and developed the Fungal Contamination Index (FCI) (Moularat et al., 2008a,b). This index has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected. However, even though the FCI has been widely tested, VOCs’ analysis by GC/MS, which is required for index calculation, is incompatible with real-time monitoring strategy for indoor environments. In this context, researches around FCI exploitation have been followed up in order to provide a monitoring device widely deployable which is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This device is based on one hand the selection and concentration of chemical compounds from the sample of interest and on the other hand the development of an array of different conducting polymer based sensors in order to obtain a specific footprint. This fungal contamination detection device was the subject of patent applications by the CSTB. The modularity of the system (ability to vary both the elements of detection polymers and retention time of interest) allows for expansion of its use to other pollutants. [ABSTRACT FROM AUTHOR]

Scientific interest in SOA influence on indoor air quality increases since last 20 years. It is well known, that particles of nano-sized diameter pose a threat for human health causing, among others: eye, upper airway irritation, inflammatory response in cells, worsening asthma, hypertension, diabetes, and central nervous dysfunction. Terpenes are reactive VOCs, commonly emitted in indoor air and considered to be SOA precursors by oxidation reactions. The aim of this study was to investigate the relative humidity influence on i) formation of limonene ozonolysis products and ii) SOA formation process – especially the first steps of it. We managed to determine 4 uncommon limonene ozonolysis products (m / z : 43, 83, 99 and 110) appearing in the PTR-TOF-MS mass spectra with the same frequency as well-known formaldehyde, acetone, acetic acid and formic acid. We also detected m / z 75 and m / z 115 formed under dry conditions and m / z 111 and m / z 125 formed under humid conditions. Detected masses formula is proposed with probability >70 % and the probability is derived from the deviation of the exact mass to the measured one and the isotope distribution. SMPS data analysis allowed us to conclude that RH around 40% increases particle mass concentration, regardless initial limonene concentration. Unfortunately, conclusions about RH influence on particle number concentration are inconsistent. Under low initial terpene concentration, RH around 40% decreases particle number concentration. However, for high initial limonene concentration, RH around 40% caused increase in particle number concentration. Obtained results allowed to conclude, that i) RH influences both particle number and particle mass concentration, ii) initial substrate concentration influences SOA formation altering the RH effect, iii) comparison of results and drawing conclusions is difficult due to different experimental protocols in the literature and due to the number of factors influencing SOA formation initiated by terpene oxidation. [Display omitted] • Specific, uncommon limonene ozonolysis products are formed under dry and humid conditions. • Increased RH increases particle mass concentration regardless initial terpene concentration. • Increased RH causes decrease in particle number concentration for experiments with low initial terpene concentration. • RH influence on particle number concentration is unclear for experimental with high initial terpene concentration. • Substrate concentration influences SOA formation, particle concentration and size distribution over time. [ABSTRACT FROM AUTHOR]

Hairdressing personnel is daily exposed to various chemical air pollutants, and specifically to Volatile Organic Compounds (VOCs) and Particulate Matter (PM) in hair salons. This is of concern, due to the hazardous effects of these chemicals on the individual's health. Nevertheless, a limited exposure assessment of indoor air quality (IAQ) has been performed. The aim of this study was to analyze the indoor air in 5 hair salons, to assess the IAQ of the occupational exposure, and to identify the main VOCs produced or activities responsible for the respective indoor pollution. The chemical analysis took place inside the salon environment by monitoring the emitted VOCs, as well as the PM of 1, 2.5, 4, and 10 μm aerodynamic diameter. The sampling of VOCs was performed by adsorption of pollutants on Tenax TA sorbent tubes, that were subsequently analyzed using a thermal desorption unit coupled to gas chromatography/mass spectrometry (TD-GC/MS). The obtained results showed that hair products are a major source of air pollutants, as elevated concentrations of VOCs and PM are released in the working environment. Furthermore, the type and concentration of VOCs are affected by the various hair treatment activities taking place in the salons. Among the main compounds detected there was benzene, toluene, ethylbenzene, and xylenes, known as BTEX, as well as, diethyl phthalate, 1,4-dioxane, etc. More than 50 VOCs were identified (occurrence ≥60%) and 14 of them were quantified. Their average concentration levels varied from 12 μg m−3 for naphthalene to 941 μg m−3 for toluene. The measuring levels for PM revealed violations of the EPA and WHO international standards for permissible limit concentrations; this was the case in all hair treatment activities but mostly during keratin treatment. Hence, much more effort is needed to reduce the respective concentration levels of PM and VOCs, that contribute to self-reported health problems. [Display omitted] • Volatile organic compounds and particulate matter are accumulated in hair salons. • Tenax sorbent tubes were applied for sampling the airborne volatiles. • The main chemical groups identified were aromatics, alkanes, terpenes and alcohols. • Quantified values varied from 12 μg m−3 for naphthalene to 941 μg m−3 for toluene. • Elevated mass average concentrations of various particulates were measured. [ABSTRACT FROM AUTHOR]

Highlights: [•] A range of VAHs occur in the air of residential houses in Brisbane, Australia. [•] The importance of internal garages as a source of VAHs to the living area of houses particularly benzene is demonstrated. [•] The potential of less well studied VAHs such as styrene and naphthalene to adversly affect public health is shown. [•] The importance of age of house as a factor in occurrence of VAHs is shown with increasing age associated with lower VAHs. [Copyright &y& Elsevier]

Abstract: Some plants are known as indoor air purifiers. A large number of studies report kinetic purification results for an extensive panel of plants, i.e. the pollutant concentration (volatile organic compounds, as known as VOC, most of the time) is continuously monitored by gas chromatography. However, only a few papers describe the mechanisms involved in such processes. This study deals with the use of secondary ion mass spectrometry imaging as an efficient tool to locate atmospheric pollutant as bromotoluene within the Hedera helix plant (leaf, roots) and the substrate on which it was previously grown. Hedera helix plants have been placed in a pollution chamber with control of the exposure parameters. Plant and soil samples excised were transferred into a fixative solution of glutaraldehyde and paraformaldehyde for a few days, were dehydrated using ethanol and were embedded with resin. Cross sections were made from the pale brown solids obtained. Then, a device using a cathodic pulverization device capable of depositing a few nanometers of gold atoms over the sample was used to make the surface electronically conductive for the NanoSIMS. Hence, polluted and unpolluted samples of Hedera helix and substrates were obtained following a careful procedure that allowed for the discrimination between polluted and nonpolluted ones. Nanoscale spatial resolution was an invaluable tool (NanoSIMS) to achieve this, and proved that VOCs, such as bromotoluene, were actually trapped by plants such as Hedera helix. [Copyright &y& Elsevier]

A common strategy to improve indoor air quality in households burning coal and biomass is the introduction of advanced combustion solid fuel stoves, which can use existing fuels yet emit fewer pollutants. Chemical composition of PM is affected by numerous combustion parameters, but is often not considered in energy transitions, despite varying toxicity among chemical components. We analyzed PM 2.5 emissions from combustion of solid fuels (coal, wood, and straw; whole and pelletized) in a variety of stoves (cookstoves and heating stoves; traditional and semi-gasifier, including forced versus natural draft and fixed versus reciprocating grate). To assess the effects of fuel and stove type on PM 2.5 composition, we measured elemental carbon (EC), organic carbon (OC), water-soluble OC, water-soluble inorganic ions (e.g. SO 4 2−, Cl−, K+), and organic molecular markers. PM 2.5 emissions from traditional stoves were mostly carbonaceous: 76–90% organic matter (OM), 5–6% EC, and less than 2% inorganic ions. In contrast, semi-gasifier stoves emitted more inorganic PM 2.5 : on average, ions comprised 65%, 9% was OM, and 4% was EC. Within the semi-gasifier cookstoves, forced-draft cookstove emissions had lower OM (1–3%) and higher ion concentrations (84–88%) than the natural-draft cookstove (5–14% OM, 30–83% ions). Levoglucosan was detected in PM 2.5 from combustion of wood in the traditional cookstove and biomass pellets in the natural-draft semi-gasifier cookstove, but not from wood pellets in the forced-draft semi-gasifier cookstove. Across a range of different fuels and stoves, stove type influenced emitted PM composition more than fuel type, underscoring the impact of combustion conditions on PM chemical composition. Image 1 • PM emitted by traditional heating and cookstoves was mostly OM and EC. • Semi-gasifier stove PM emissions were mostly inorganic (ions), with low OM and EC. • Forced draft stove emissions had less water-soluble and total OM than natural draft. • Reciprocating grate stove emissions had less OM and EC, more ions than fixed grate. • Some coal and wood pellet PM emissions had no picene or levoglucosan (respectively). [ABSTRACT FROM AUTHOR]

Phthalates (PAEs) are a group of typical semivolatile organic compounds that are widely present in indoor environments with multiple phases. Indoor air, airborne particle and settled dust are considered to be typical indicators of PAE contamination as well as media of human exposure, and the interactions between them are complex. Among various phthalate compounds, di 2-ethylhexyl phthalate (DEHP) was identified as the predominant individual phthalate in settled dust. The existing DEHP contamination assessment requires multiphase sampling or solving the dynamic mass transfer models with multiple partial differential equations, which are both complicated and time-consuming. This study investigated the influence of the indoor source loading rate, surface type, particle size and cleaning frequency on the partitioning between the settled dust-phase, airborne particle-phase and gas-phase. The concentration correlations of DEHP between multiphases were consequently derived, which balance accuracy and complexity well. By comparison with field sampling data in the literatures, the rationality and accuracy of the concentration correlations were validated. Based on the concentration correlations, a new method of directly using dust-phase concentration to estimate the non-dietary exposure to DEHP was proposed. The results indicated that ingestion of settled dust contributes the most to non-dietary exposure. Special attention should be given to infants and toddlers, who suffer the highest daily exposure to DEHP among all age groups. This study provides a new and efficient solution for estimating indoor DEHP pollution loads conveniently and rapidly, offering valuable insights for future research in this field. [Display omitted] • Settled dust can be regarded as the passive sampling medium of DEHP. • The concentration correlations between multi-phase DEHP were derived. • Non-dietary exposure was assessed using the dust-phase concentration. • This study provides an efficient solution for estimating indoor DEHP contamination. [ABSTRACT FROM AUTHOR]

Buildings contaminated with polychlorinated biphenyls (PCBs) are a health concern for the building occupants. Inhalation exposure is linked to indoor air concentrations of PCBs, which are known to be affected by indoor temperatures. In this study, a highly PCB contaminated room was heated to six temperature levels between 20 and 30 C, i.e. within the normal fluctuation of indoor temperatures, while the air exchange rate was constant. The steady-state air concentrations of seven PCBs were determined at each temperature level. A model based on Clausius–Clapeyron equation, ln( P ) = −ΔH/RT + a 0 , where changes in steady-state air concentrations in relation to temperature, was tested. The model was valid for PCB-28, PCB-52 and PCB-101; the four other congeners were sporadic or non-detected. For each congener, the model described a large proportion (R 2 >94%) of the variation in indoor air PCB levels. The results showed that one measured concentration of PCB at a known steady-state temperature can be used to predict the steady-state concentrations at other temperatures under circumstances where e.g. direct sunlight does not influence temperatures and the air exchange rate is constant. The model was also tested on field data from a PCB remediation case in an apartment in another contaminated building complex where PCB concentrations and temperature were measured simultaneously and regularly throughout one year. The model fitted relatively well with the regression of measured PCB air concentrations, ln( P ) vs. 1/ T , at varying temperature between 16.3 and 28.2 °C, even though the measurements were carried out under uncontrolled environmental condition. [ABSTRACT FROM AUTHOR]

Exposure to cleaning products has been associated with harm to the respiratory system, neurotoxicity, harm to the reproductive system, and elevated risk of cancer, with greatest adverse impacts for workers exposed in an occupational setting. Social and consumer interest in cleaning products that are safer for health created a market category of "green" products defined here as products advertised as healthier, non-toxic, or free from harmful chemicals as well as products with a third-party certification for safety or environmental features. In the present study we examined the air quality impacts of cleaning products and air fresheners, measuring the number, concentrations, and emission factors of volatile organic compounds (VOCs) in an air chamber following product application. Across seven common product categories, 30 products were tested overall including 14 conventional, 9 identified as "green" with fragrance, and 7 identified as "green" and fragrance-free. A total of 530 unique VOCs were quantified with 205 additional VOCs detected below the limits of quantification. Of the quantifiable VOCs, 193 were considered hazardous according to either the California's Department of Toxic Substances Control Candidate Chemicals List or the European Chemical Agency's Classification and Labeling Inventory. The total concentration of VOCs and total emission factors across all products with detections ranged from below limits of detection to 18,708 μg/m3, 38,035 μg/g product and 3803 μg/application. Greater total concentration, total emission factors, and numbers of VOCs were generally observed in conventional cleaning products compared to products identified as "green", particularly compared to fragrance-free products. A hazard index approach was utilized to assess relative risk from measured VOC emissions. The five products with the highest hazard indices were conventional products with emissions of 2-butoxyethanol, isopropanol, toluene and chloroform. Overall, this analysis suggests that the use of "green" cleaning products, especially fragrance-free products, may reduce exposure to VOC emissions. [Display omitted] • Air chamber testing of 28 cleaning products and 2 air fresheners detected 530 VOCs. • The number and concentrations of VOCs were lower in "green" products. • Fragrance-free products had significantly lower numbers and concentrations of VOCs. • Exposure limits were used to calculate relative risk for each product. [ABSTRACT FROM AUTHOR]

Fifteen carbonyl compounds were investigated in the living rooms and bedrooms of 25 university student flats in the urban area of Ciudad Real (Central Southern Spain) in wintertime. Carbonyls were sampled using Radiello ® passive samplers refilled in the laboratory according to the method described in ISO 16000-3 Standard. The most abundant carbonyls in the living rooms and bedrooms were formaldehyde, acetone, acetaldehyde, hexaldehyde and butyraldehyde. The median concentration levels in the living rooms and bedrooms were: 28.6 and 34.2 μg m−3 for formaldehyde, 18.3 and 23.1 μg m−3 for acetone, 14.3 and 15.8 μg m−3 for acetaldehyde, 11.4 and 14.1 μg m−3 for hexaldehyde and 10.8 and 12.4 μg m−3 for butyraldehyde. The median concentration of formaldehyde, benzaldehyde, valeraldehyde and hexaldehyde was significantly higher in the bedrooms than in the living rooms. Indoor concentrations were significantly higher than outdoor concentrations for all carbonyl measured, indicating that sources in the indoor environment are prevailing in all flats. Principal component analysis, multiple linear regressions and Spearman correlation coefficients were used to investigate the origin, the indoor pollutants determinants and to establish common sources between carbonyls. Eight components were extracted from the application of PCA to the indoor and outdoor measurements accounting for 97.7% of the total variance. Formaldehyde, acetone, acetaldehyde and acrolein presented different indoor sources. In the multiple linear regression analysis, higher formaldehyde concentrations were found in those living rooms with wood floor and smoking was positively associated to acetone, propionaldehyde, benzaldehyde and isovaleraldehyde. Formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde and benzaldehyde concentrations were compared with relevant international guidelines, being their concentrations below recommended values except acrolein, where all measured flats exceeded the reference levels; it would be important to focus on the characterization of emission sources of acrolein in indoor air in order to minimise the exposure and health risk. [Display omitted] • Radiello ® passive samplers refilled in the laboratory can be considered to measure carbonyl compounds in indoor air. • The median concentration of formaldehyde, benzaldehyde, valeraldehyde and hexaldehyde was significantly higher in the bedrooms. • The median concentration levels in bedrooms (µg m-3) were 34.2 for formaldehyde, 23.1 for acetone and 15.8 for acetaldehyde. • Indoor sources in university student flats played a decisive role in the concentrations of all measured carbonyls. • All the carbonyls levels are below recommended indoor air quality guidelines except acrolein. [ABSTRACT FROM AUTHOR]

Abstract: The photocatalytic elimination of microorganisms from indoor air in realistic conditions and the feasibility of simultaneous elimination of chemical contaminants have been studied at laboratory scale. Transparent polymeric monoliths have been coated with sol–gel TiO2 films and used as photocatalyst to treat real indoor air in a laboratory-scale single-step annular photocatalytic reactor. The analytical techniques used to characterize the air quality and analyze the results of the photocatalytic tests were: colony counting, microscopy and PCR with subsequent sequencing for microbial quantification and identification; automated thermal desorption coupled to gas chromatography with mass spectrometry detection for chemical analysis. The first experiments performed proved that photocatalysis based on UVA-irradiated TiO2 for the reduction of the concentration of bacteria in the air could compete with the conventional photolytic treatment with UVC radiation, more expensive and hazardous. Simultaneously to the disinfection, the concentration of volatile organic compounds was greatly reduced, which adds value to this technology for real applications. The fungal colony number was not apparently modified. [Copyright &y& Elsevier]

Exposure to phthalates poses adverse health impacts to human beings. In this study, we analyzed 7 phthalates in dust samples, which were collected with vacuum cleaner from 40 to 31 residences in Beijing in summer and winter, respectively. The major phthalates (median concentration in the summer and winter, respectively) were D i BP (55 and 40 ng/mg), D n BP (99 and 30 ng/mg) and DEHP (795 and 335 ng/mg). The concentrations were significantly influenced by season and residence time of house dust. The concentrations of phthalates in dust on plastic surfaces were highest, followed by those on wooden and fabric surfaces. The dust-air partition coefficients (K d) were calculated: the median values were 0.13, 0.02 and 5.62 m3/mg in the summer and 0.06, 0.018 and 0.76 m3/mg in the winter for D i BP, D n BP and DEHP, respectively. A comparison with K d * at equilibrium state suggested that partition between air and dust deviated from equilibrium state in both seasons. The results also revealed that dust-phthalates in the summer may completely originate from source materials via direct transfer and external physical process; while dust-phthalates in the winter may come from both air (via partition) and source material (via direct transfer and external physical process). The influence of temperature on dust-phthalate concentrations differed by season, owing to different origin of dust-phthalates in two seasons. Polar organic components in dust, which are products of reactions between O 3 and unsaturated hydrocarbons in dust, likely played an important role in fate and transport of phthalates. The presence of them resulted in the significant associations between dust-phthalate concentrations and air humidity in the summer. Moreover, the impacts of indoor PM 2.5 concentrations, traffic conditions surrounding residence, household lifestyle and number of occupants were also observed. The mechanisms behind those observations were discussed. [Display omitted] • Dust-air partition of phthalates deviated from equilibrium state. • Product-to-dust phthalates migration included direct transfer and external process. • Origin of dust-phthalates may differ by season. • Built environmental determinants on dust-phthalate concentrations were characterized. [ABSTRACT FROM AUTHOR]

As more people are spending the majority of their daily lives indoors, indoor air quality has been acknowledged as an important factor influencing human health, with increasing research attention in recent decades. Indoor air pollutants (IAPs), such as volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), can cause acute irritation and chronic diseases. Photocatalytic oxidation (PCO) technology is an efficient approach for eliminating IAPs. In this review, the development of PCO technology was explained and discussed to promote future development of PCO technology for IAP elimination. First, the health effects and the measured concentrations of typical VOCs and SVOCs in indoor environments worldwide were briefly introduced. Subsequently, the development and limitations of some typical photocatalytic reactors (including packed-bed reactors, monolithic reactors, optical fiber reactors, and microreactors) were summarized and compared. Then, the influences of operating parameters (including initial concentration of contaminants, relative humidity, space velocity, light source and intensity, catalyst support materials, and immobilization method) and the degradation pathways as well as intermediates of PCO technology were elucidated. Finally, the possible challenges and future development directions regarding PCO technology for IAP elimination were critically proposed and addressed. [Display omitted] • Semi-volatile organic compounds are common indoor air pollutants (IAPs). • Photocatalytic oxidation technology is an effective technology for IAPs elimination. • Development of photocatalytic reactors are summarized and compared. • Influence of operating parameters on photocatalytic oxidation efficiency is reviewed. • Intermediates and degradation pathways of IAPs are elucidated. [ABSTRACT FROM AUTHOR]

As many people spend a large part of their life indoors, the quality of the indoor environment is important. Data on contaminants such as flame retardants, pesticides and plasticizers are available for indoor air and dust but are scarce for consumer products such as computers, televisions, furniture, carpets, etc. This review presents information on semi-volatile organic compounds (SVOCs) in consumer products in an attempt to link the information available for chemicals in indoor air and dust with their indoor sources. A number of 256 papers were selected and divided among SVOCs found in consumer products (n = 57), indoor dust (n = 104) and air (n = 95). Concentrations of SVOCs in consumer products, indoor dust and air are reported (e.g. PFASs max: 13.9 μg/g in textiles, 5.8 μg/kg in building materials, 121 ng/g in house dust and 6.4 ng/m 3 in indoor air). Most of the studies show common aims, such as human exposure and risk assessment. The main micro-environments investigated (houses, offices and schools) reflect the relevance of indoor air quality. Most of the studies show a lack of data on concentrations of chemicals in consumer goods and often only the presence of chemicals is reported. At the moment this is the largest obstacle linking chemicals in products to chemicals detected in indoor air and dust. [ABSTRACT FROM AUTHOR]

The abatement of indoor volatile organic compounds (VOCs) represents a major challenge due to their environmental risk, wide nature and concentration variability. Biotechnologies represent a cost-effective, robust and sustainable platform for the treatment of hazardous VOCs at low and fluctuating concentrations. However, they have been scarcely implemented for indoor air purification. Thus, little is known about the influence of the reactor configuration or the VOC nature and concentration variability on the removal, resilience and the microbial population of bioreactor configurations susceptible to be implemented, both in indoors and industrial environments. The present study aims at comparing the removal performance of four VOCs with different hydrophobicity and molecular structure -acetone, n -hexane, α-pinene and toluene-at two inlet concentrations (5 and 400 mg m−3), which mimics the concentrations of contaminated indoor and industrial air. To this aim a stirred tank, flat biofilm and latex-based biocoated flat bioreactor were comparatively evaluated. The results demonstrated the superior performance of the stirred tank reactor for the removal of hydrophilic VOCs at high inlet concentrations, which achieved removals >99% for acetone and toluene. At low concentrations, the removal efficiencies of acetone, toluene and α-pinene were >97% regardless of the bioreactor configuration tested. The most hydrophobic gas, n -hexane, was more efficiently removed in the flat biofilm reactor without latex. The microbial community analyses showed that the presence of VOCs as the only carbon and energy source didn't promote the growth of dominant bacterial members and the populations independently evolved in each reactor configuration and operation mode. The fungal population was more diverse in the biofilm-based bioreactors, although, it was mainly dominated by uncultured fungi from the phylum Cryptomycota. [Display omitted] • Comparison of different reactor configurations for the removal of indoor air VOCs. • The stirred tank reactor showed the best VOC removals at high inlet concentrations. • VOC removals>97% achieved at low inlet concentration in all reactor configurations. • n -hexane was more efficiently removed in a flat biofilm reactor without latex. • The specific operation mode affected the bacterial and fungal population. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) enter indoor environments through internal and external sources. Indoor air concentrations of VOCs vary greatly but are generally higher than outdoors. Plants have been promoted as indoor air purifiers for decades, but reports of their effectiveness differ. However, while air-purifying applications may be questionable, the waxy cuticle coating on leaves may provide a simple, cost-effective approach to sampling indoor air for VOCs. To investigate the potential use of plants as indoor air VOC samplers, a static headspace approach was used to examine the relationship between leaf and air concentrations, leaf lipid contents and octanol-air partition coefficients (Koa) for six VOCs and four plant species. The relationship between leaf and air concentrations was further examined in an actual residence after the introduction of several chlorinated VOC emission sources. Leaf-air concentration factors (LACFs), calculated from linear regressions of the laboratory headspace data, were found to increase as the solvent extractable leaf lipid content and Koa value of the VOC increased. In the studies conducted in the residence, leaf concentrations paralleled the changing air concentrations, indicating a relatively rapid air to leaf VOC exchange. Overall, the data from the laboratory and residential studies illustrate the potential for plant leaves to be used as cost effective, real-time indoor air VOC samplers. [ABSTRACT FROM AUTHOR]

Epiphytic Tillandsia (Bromeliaceae) species have been found to be efficient biomonitors of atmospheric heavy metals and persistent organic pollutants, but have not been used to monitor or remove the primary indoor atmospheric pollutant formaldehyde (FA). The absorptive capacity of Tillandsia trichomes is well-established, but potential secondary effects of foliar trichomes on gas exchange remain unclear. Our study investigated whether Tillandsia species can absorb FA efficiently and if the leaf trichomes function to improve FA uptake, using Tillandsia velutina . Plants with intact trichomes, decreased FA concentration by 48.42% in 12 h from 1060 μg m − 3 to 546.67 μg m − 3 , while FA concentration decreased only by 22.51% in the plants without trichomes. Moreover, the more trichomes removed from the leaves, the lower the capability of FA uptake per unit leaf area, which suggested that T. velutina was capable of absorbing a large amount of FA via the leaves and specialized trichomes facilitated the whole leaf tissue FA absorption. In addition, all plants exposed to FA were chloric, had a reduction in measured leaf chlorophyll, and an increment in permeability of plasma membranes. However, plants in which trichomes had been removed declined or increased more quickly than plants with intact trichomes, indicating Tillandsia leaf trichomes also give the leaves some protection against this toxin. [ABSTRACT FROM AUTHOR]