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Children, an important vulnerable group, spend most of their time at schools (up to 10 h per day, mostly indoors) and the respective air quality may significantly impact on children health. Thus, this work reviews the published studies on children biomonitoring and environmental exposure to particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) at school microenvironments (indoors and outdoors), major sources and potential health risks. A total of 28, 35, and 31% of the studies reported levels that exceeded the international outdoor ambient air guidelines for PM10, PM2.5, and benzo(a)pyrene, respectively. Indoor and outdoor concentrations of PM10 at European schools, the most characterized continent, ranged between 7.5 and 229 μg/m3 and 21–166 μg/m3, respectively; levels of PM2.5 varied between 4 and 100 μg/m3 indoors and 6.1–115 μg/m3 outdoors. Despite scarce information in some geographical regions (America, Oceania and Africa), the collected data clearly show that Asian children are exposed to the highest concentrations of PM and PAHs at school environments, which were associated with increased carcinogenic risks and with the highest values of urinary total monohydroxyl PAH metabolites (PAH biomarkers of exposure). Additionally, children attending schools in polluted urban and industrial areas are exposed to higher levels of PM and PAHs with increased concentrations of urinary PAH metabolites in comparison with children from rural areas. Strong evidences demonstrated associations between environmental exposure to PM and PAHs with several health outcomes, including increased risk of asthma, pulmonary infections, skin diseases, and allergies. Nevertheless, there is a scientific gap on studies that include the characterization of PM fine fraction and the levels of PAHs in the total air (particulate and gas phases) of indoor and outdoor air of school environments and the associated risks for the health of children. There is a clear need to improve indoor air quality in schools and to establish international guidelines for exposure limits in these environments. Keywords: Biomarkers, Children exposure, Health effects, Particulate matter (PM), Polycyclic aromatic hydrocarbons (PAHs)

Air pollution has been associated with childhood neurodevelopment. However, the role of indoor air pollution, especially volatile organic compounds (VOCs), on childhood neurodevelopment has been poorly explored to date. We investigated the association between indoor air pollutants and childhood neurodevelopment in 5,017 randomly selected children from the Japan Environment and Children’s Study. When the participants reached 1.5 and 3 years of age, they were followed up with home visits and neurodevelopmental tests using the Ages and Stages Questionnaire (ASQ). At both ages, we collected indoor air samples for 1 week and measured 13 indoor air pollutants: particulate matter with an aerodynamic diameter of ≤2.5 μm, ozone, nitrogen dioxide, sulfur dioxide, and nine VOCs. The associations between air pollutants and ASQ scores were estimated using linear mixed effects models and weighted quantile sum regressions (WQS) at each age separately. Stratified analysis by sex was conducted. Exposure to m,p-xylene at the age of 3 was associated with lower communication, fine motor, and overall ASQ scores (coefficients: −0.18 [99% confidence intervals (CI): −0.35, −0.02], −0.23 [99 %CI: −0.43, −0.03], and − 0.72 [99 %CI: −1.41, −0.04] per 1 µg/m3 increase, respectively). Exposure to o-xylene at the age of 3 was associated with lower communication, gross motor, fine motor, and overall ASQ scores (coefficients: −0.48 [99 %CI: −0.90, −0.07], −0.45 [99 %CI: −0.78, −0.13], −0.65 [99 %CI: −1.14, −0.16], and −2.15 [99 %CI: −3.83, −0.47] per 1 µg/m3 increase, respectively). The WQS index was associated with lower gross motor ASQ scores at the age of 3 (coefficient: −0.27 [95 %CI: −0.51, −0.03] for one-unit WQS index increases), which was attributed to benzene (33.96%), toluene (26.02%), o-xylene (13.62%), and ethylbenzene (9.83%). Stratified analysis showed similar results. Although further investigations are required, our results suggest an association of neurodevelopmental delays with indoor low-level exposure to m,p-xylene and o-xylene in early life.

More than 1 million premature deaths in Asia annually are estimated to be associated with indoor air quality. HEPA (high-efficiency particulate air) filter air purifiers (APs) are widely used in urban Chinese residences by the growing middle class, as public awareness of air pollution increases. Currently, understanding of how particle size affects particle removal is inconsistent, and the rate at which different particle types are removed remains largely unknown. Therefore, this investigation aimed to determine the relationship between particle size and the removal efficiency of particles, and how efficiently ambient air is filtered compared to particle types which are typically used in standard tests (tobacco smoke, dust and pollen). Three of the most popular AP models in China were tested in China’s largest indoor controlled chamber laboratory and the removal efficiencies of particles in the 18–514 nm range were identified. Each AP had a distinct profile of removal efficiency against particle size, but the three APs shared similarities in performance, with removal efficiency consistently lowest at 200–250 nm. This size fraction is important in an exposure context as these particles are abundant in ambient air in mega-cities, can penetrate through building shells effectively, remain airborne for long periods of time and can penetrate the deepest areas of the lungs. Ambient air particles were removed at a similar rate to test particles; this confirms that the Association of Home Appliance Manufacturers’ (AHAM) standards are a suitable proxy for “real world” performance.

A large population does not have access to modern household energy and relies on solid fuels such as coal and biomass fuels. Burning of these solid fuels in low-efficiency home stoves produces high amounts of multiple air pollutants, causing severe air pollution and adverse health outcomes. In evaluating impacts on human health and climate, it is critical to understand the formation and emission processes of air pollutants from these combustion sources. Air pollutant emission factors (EFs) from indoor solid fuel combustion usually highly vary among different testing protocols, fuel-stove systems, sampling and analysis instruments, and environmental conditions. In this critical review, we focus on the latest developments in pollutant emission factor studies, with emphases on the difference between lab and field studies, fugitive emission quantification, and factors that contribute to variabilities in EFs. Field studies are expected to provide more realistic EFs for emission inventories since lab studies typically do not simulate real-world burning conditions well. However, the latter has considerable advantages in evaluating formation mechanisms and variational influencing factors in observed pollutant EFs. One main challenge in field emission measurement is the suitable emission sampling system. Reasons for the field and lab differences have yet to be fully elucidated, and operator behavior can have a significant impact on such differences. Fuel properties and stove designs affect emissions, and the variations are complexly affected by several factors. Stove classification is a challenge in the comparison of EF results from different studies. Lab- and field-based methods for quantifying fugitive emissions, as an important contributor to indoor air pollution, have been developed, and priority work is to develop a database covering different fuel-stove combinations. Studies on the dynamics of the combustion process and evolution of air pollutant formation and emissions are scarce, and these factors should be an important aspect of future work.

Background Air pollution in subway environments is a growing concern as it often exceeds WHO recommendations for indoor air quality. Ultrafine particles (UFP), for which there is still no regulation nor a standardized exposure monitoring method, are the strongest contributor to this pollution when the number concentration is used as exposure metric. Objectives We aimed to assess the real-time UFP number concentration in the personal breathing zone (PBZ) of three types of underground Parisian subway professionals and analyze it using a novel Bayesian spline approach. Consecutively, we investigated the effect of job, week day, subway station, worker location, and some further events on UFP number concentrations. Methods The data collection procedure originated from a longitudinal study and lasted for a total duration of 6 weeks (from October 7 to November 15, 2019, i.e. two weeks per type of subway professionals). Time-series were built from the real-time particle number concentration (PNC) measured in the PBZ of professionals during their work-shifts. Complementarily, contextual information expressed as Station, Environment, and Event variables were extracted from activity logbooks completed for every work-shift. A Bayesian spline approach was applied to model the PNC within a Bayesian framework as a function of the mentioned contextual information. Results Overall, the Bayesian spline method suited a real-time personal PNC data modeling approach. The model enabled estimating the differences in UFP exposure between subway professionals, stations, and various locations. Our results suggest a higher PNC closer to the subway tracks, with the highest PNC on subway station platforms. Studied event and week day variables had a lesser influence. Conclusion It was shown that the Bayesian spline method is suitable to investigate individual exposure to UFP in underground subway settings. This method is informative for better documenting the magnitude and variability of UFP exposure, and for understanding the determinants in view of further regulation and control of this exposure.

Graphical abstract, Background Ambient and household air pollution are found to lead to premature deaths from all-cause or cause-specific death. The national lockdown measures in China during COVID-19 were found to lead to abrupt changes in ambient surface air quality, but indoor air quality changes were neglected. In this study, we aim to investigate the impacts of lockdown measures on both ambient and household air pollution as well as the short-term health effects of air pollution changes. Methods In this study, an up-to-date emission inventory from January to March 2020 in China was developed based on air quality observations in combination with emission-concentration response functions derived from chemical transport modeling. These emission inventories, together with the emissions data from 2017 to 2019, were fed into the state-of-the-art regional chemistry transport model to simulate the air quality in the North China Plain. A hypothetical scenario assuming no lockdown effects in 2020 was also performed to determine the effects of the lockdown on air quality in 2020. A difference-to-difference approach was adopted to isolate the effects on air quality due to meteorological conditions and long-term decreasing emission trends by comparing the PM2.5 changes during lockdown to those before lockdown in 2020 and in previous years (2017–2019). The short-term premature mortality changes from both ambient and household PM2.5 changes were quantified based on two recent epidemiological studies, with uncertainty of urban and rural population migration considerations. Findings The national lockdown measures during COVID-19 led to a reduction of 5.1 µg m−3 in ambient PM2.5 across the North China Plain (NCP) from January 25th to March 5th compared with the hypothetical simulation with no lockdown measures. However, a difference-to-difference method showed that the daily domain average PM2.5 in the NCP decreased by 9.7 µg m−3 between lockdown periods before lockdown in 2020, while it decreased by 7.9 µg m−3 during the same periods for the previous three-year average from 2017 to 2019, demonstrating that lockdown measures may only have caused a 1.8 µg m−3 decrease in the NCP. We then found that the integrated population-weighted PM2.5, including both ambient and indoor PM2.5 exposure, increased by 5.1 µg m−3 during the lockdown periods compared to the hypothetical scenario, leading to additional premature deaths of 609 (95% CI: 415–775) to 2,860 (95% CI: 1,436–4,273) in the short term, depending on the relative risk chosen from the epidemiological studies. Interpretation Our study indicates that lockdown measures in China led to abrupt reductions in ambient PM2.5 concentration but also led to significant increases in indoor PM2.5 exposure due to confined indoor activities and increased usages of household fuel for cooking and heating. We estimated that hundreds of premature deaths were added as a combination of decreased ambient PM2.5 and increased household PM2.5. Our findings suggest that the reduction in ambient PM2.5 was negated by increased exposure to household air pollution, resulting in an overall increase in integrated population weighted exposure. Although lockdown measures were instrumental in reducing the exposure to pollution concentration in cities, rural areas bore the brunt, mainly due to the use of dirty solid fuels, increased population density due to the large-scale migration of people from urban to rural areas during the Chinese New Year and long exposure time to HAP due to restrictions in outdoor movement.

Despite the fact that the special characteristics of indoor air pollution make closed environments quite different from outdoor environments, the conceptual ideas for assessing air quality indoors and outdoors are similar. Therefore, the elaboration of International Standards for air quality characterization in view of controlling indoor air quality should resort to this common basis. In this short review we describe the possibilities of standardization of tools dedicated to indoor air quality characterization with a focus on the tools permitting to study the indoor air chemistry. The link between indoor exposure and health as well as the critical processes driving the indoor air quality are introduced. Available International Standards for the assessment of indoor air quality are depicted. The standards comprise requirements for the sampling on site, the analytical procedures, and the determination of material emissions. To date, these standardized procedures assure that indoor air, settled dust and material samples are analyzed in a comparable manner. However, existing International Standards exclusively specify conventional, event-driven target-screening using discontinuous measurement methods for long-lived pollutants. Therefore, this review draws a parallel between physico-chemical processes in indoor and outdoor environments. The achievements in atmospheric sciences also improve our understanding of indoor environments. The community of atmospheric scientists can be both ideal and supporter for researchers in the area of indoor air quality characterization.This short review concludes with propositions for future standardization activities for the chemical characterization of indoor air quality. Future standardization efforts should focus on: (i) the elaboration of standardized measurement methods and measurement strategies for online monitoring of long-lived and short-lived pollutants, (ii) the assessment of the potential and the limitations of non-target screening, (iii) the paradigm shift from event-driven investigations to systematic approaches to characterize indoor environments, and (iv) the development of tools for policy implementation. Keywords: Indoor air quality, Indoor air chemistry, Online-measurement, Non-target-screening, Indoor air quality management

Improper natural ventilation practices may deteriorate indoor air quality when in close proximity to roadways, although the intention is often to reduce energy consumption. In this study, we employed a CFD-based air quality model to quantify the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building. Our study found that the building envelope restricts dispersion and dilution of particulate matter. The indoor concentration in the baseline condition located 10 m away from the roadway is roughly 16–21% greater than that at the edge of the roadway. The indoor flow recirculation creates a well-mixed zone with little variation in fine particle concentration (i.e., 253 nm). For ultrafine particles (

Several tiny organisms of various size ranges present in air are called airborne particles or bioaerosol which mainly includes live or dead fungi and bacteria, their secondary metabolites, viruses, pollens, etc. which have been related to health issues of human beings and other life stocks. Bio-terror attacks in 2001 as well as pandemic outbreak of flue due to influenza A H1N1 virus in 2009 have alarmed us about the importance of bioaerosol research. Hence characterization i.e. identification and quantification of different airborne microorganisms in various indoor environments is necessary to identify the associated risks and to establish exposure threshold. Along with the bioaerosol sampling and their analytical techniques, various literatures revealing the concentration levels of bioaerosol have been mentioned in this review thereby contributing to the knowledge of identification and quantification of bioaerosols and their different constituents in various indoor environments (both occupational and non-occupational sections). Apart from recognition of bioaerosol, developments of their control mechanisms also play an important role. Hence several control methods have also been briefly reviewed. However, several individual levels of efforts such as periodic cleaning operations, maintenance activities and proper ventilation system also serve in their best way to improve indoor air quality., Highlights • Bioaerosol distribution is highly dependent on seasons and is found to be higher in summer and fall and lowest in winter. • Impaction though mostly used but is not suitable for highly contaminated environment due to overloading problem. • Among all the enumeration techniques microscopic technique has been mostly used for bioaerosol identification. • Among many diseases caused by bioaerosols SARS and tuberculosis are diseases that cause maximum socio-economic impacts. • There are many control mechanisms but hybrid mechanism (combination of different methods) is the most efficient.

Studies of air pollution effects during pregnancy generally only consider exposure in the outdoor air at the home address. We aimed to compare exposure models differing in their ability to account for the spatial resolution of pollutants, space–time activity and indoor air pollution levels. We recruited 40 pregnant women in the Grenoble urban area, France, who carried a Global Positioning System (GPS) during up to 3 weeks; in a subgroup, indoor measurements of fine particles (PM2.5) were conducted at home (n = 9) and personal exposure to nitrogen dioxide (NO2) was assessed using passive air samplers (n = 10). Outdoor concentrations of NO2, and PM2.5 were estimated from a dispersion model with a fine spatial resolution. Women spent on average 16 h per day at home. Considering only outdoor levels, for estimates at the home address, the correlation between the estimate using the nearest background air monitoring station and the estimate from the dispersion model was high (r = 0.93) for PM2.5 and moderate (r = 0.67) for NO2. The model incorporating clean GPS data was less correlated with the estimate relying on raw GPS data (r = 0.77) than the model ignoring space–time activity (r = 0.93). PM2.5 outdoor levels were not to moderately correlated with estimates from the model incorporating indoor measurements and space–time activity (r = −0.10 to 0.47), while NO2 personal levels were not correlated with outdoor levels (r = −0.42 to 0.03). In this urban area, accounting for space–time activity little influenced exposure estimates; in a subgroup of subjects (n = 9), incorporating indoor pollution levels seemed to strongly modify them. Keywords: Exposure assessment, Air pollutants, Space–time activity, Global Positioning System, Indoor environment, Pregnancy

Although the evaluation of air quality in the residential and office rooms has been significantly developed in recent decades, the issues associated with securing the air quality requirements in nurseries are still not well recognised. This study presents the results of tests regarding the physical and microbiological properties of air in selected rooms of a nursery, including the alternatively variable way of rooms ventilation. The experiment was conducted in four different rooms from the 20th of November 2017 to the 16th of April 2018. The constant measurements of basic parameters of physical air quality in rooms and outside as well as the measurements of microbiological and particulate matter contaminations were conducted in the chosen days of the analysis. The results have confirmed the unsatisfactory air quality in the rooms dedicated to small children. Modernisation of the ventilation system, from a natural one to the supply-exhaust ventilation, has lead to an improvement of physical property of the air, but it did not significantly improve its microbiological quality. Our research indicates that the controlled air flow, method of cleaning the premise and health condition of the children may have a great influence on the physical and microbiological quality of the air. Keywords: Nursery, Indoor air quality, Microbiological contaminations, CO2 concentration, particulate matter, mechanical ventilation

Background: Decades of intervention programs that replaced traditional biomass stoves with cleaner-burning technologies have failed to meet the World Health Organization (WHO) interim indoor air quality target of 35-μg m−3 for PM2.5. Many attribute these results to continued use of biomass stoves and poor outdoor air quality, though the relative impacts of these factors have not been empirically quantified. Methods: We measured 496 days of real-time stove use concurrently with outdoor and indoor air pollution (PM2.5) in 150 rural households in Sichuan, China. The impacts of stove use patterns and outdoor air quality on indoor PM2.5 were quantified. We also estimated the potential avoided cardiovascular mortality in southwestern China associated with transition from traditional to clean fuel stoves using established exposure-response relationships. Results: Mean daily indoor PM2.5 was highest in homes using both wood and clean fuel stoves (122 μg m−3), followed by exclusive use of wood stoves (106 μg m−3) and clean fuel stoves (semi-gasifiers: 65 μg m−3; gas or electric: 55 μg m−3). Wood stoves emitted proportionally higher indoor PM2.5 during ignition, and longer stove use was not associated with higher indoor PM2.5. Only 24% of days with exclusive use of clean fuel stoves met the WHO indoor air quality target, though this fraction rose to 73% after subtracting the outdoor PM2.5 contribution. Reduced PM2.5 exposure through exclusive use of gas or electric stoves was estimated to prevent 48,000 yearly premature deaths in southwestern China, with greater reductions if local outdoor PM2.5 is also reduced. Conclusions: Clean stove and fuel interventions are not likely to reduce indoor PM2.5 to the WHO target unless their use is exclusive and outdoor air pollution is sufficiently low, but may still offer some cardiovascular benefits. Keywords: Biomass, Cardiovascular mortality, Cookstoves, Liquefied petroleum gas, PM2.5, Semi-gasifier

This paper summarizes recent data on the occurrence of major organic compounds (benzene, toluene, xylenes, styrene, acetaldehyde, formaldehyde, naphthalene, limonene, α-pinene and ammonia, classified by the European Commission's INDEX strategy report as the priority pollutants to be regulated) and evaluates accordingly cancer and non-cancer risks posed by indoor exposure in dwellings and public buildings in European Union (EU) countries. The review process indicated that significant differences in indoor air quality exist within and among the countries where data were available, indicating corresponding differences in sources and emission strength of airborne chemicals, identified or not. Conservative exposure limits were not exceeded for non-carcinogenic effects, except for formaldehyde; for carcinogenic agents the estimated risks were up to three orders of magnitude higher than the one (10−6) proposed as acceptable by risk management bodies. However, the risk assessment evaluation process faces crucial difficulties, either due to the relative paucity of indoor air quality measurements in many EU countries, or by the lack of sampling consistency in the already existing studies, indicating the need for additional measurements of indoor air quality following a harmonized sampling and analytical protocol. Additionally, uncertainties embodied in the cancer potency factors and exposure limit values impose further difficulties in substance prioritization and risk management. Keywords: Volatile organic compounds, Indoor air quality, Exposure assessment, Health risk

Buildings in developed countries are becoming increasingly airtight as a response to stricter energy efficiency requirements. At the same time, changes are occurring to the ways in which household energy is supplied, distributed and used. These changes are having important impacts on exposure to indoor air pollutants in residential buildings and present new challenges for professionals interested in assessing the effects of housing on public health. In many circumstances, models are the most appropriate way with which to examine the potential outcomes of future environmental and/or building interventions and policies. As such, there is a need to consider the current state of indoor air pollution exposure modelling.Various indoor exposure modelling techniques are available, ranging from simple statistical regression and mass-balance approaches, to more complex multizone and computational fluid dynamics tools that have correspondingly large input data requirements. This review demonstrates that there remain challenges which limit the applicability of current models to health impact assessment. However, these issues also present opportunities for better integration of indoor exposure modelling and epidemiology in the future. The final part of the review describes the application of indoor exposure models to health impact assessments, given current knowledge and data, and makes recommendations aimed at improving model predictions in the future. Keywords: Indoor air quality, Exposure, Exposure modelling, Microenvironment, Computational fluid dynamics, Health impact assessment

Brominated flame retardants (BFRs) are now ubiquitous contaminants with large reservoirs and high concentrations in buildings. Most of the information documenting BFR levels has been obtained in residences, and other environments that can lead to exposure have received relatively little attention, including offices that contain numerous BFR sources and where individuals spend considerable time. The aim of this study is to characterize BFR concentrations, potential emission sources, and migration pathways in office environments. We measure BFR levels in floor dust, indoor air, ventilation filter dust, and carpets in ten commercial and institutional buildings in Michigan, U.S.A. The median concentration of total BDEs in settled dust was 8754 ng g−1, at the upper range of levels previously reported. Especially elevated levels were found in offices in buildings that contained known or likely BFR sources, e.g., computer servers. A trends analysis in a newly constructed building showed remarkable increases in concentrations of BFRs in settled dust and indoor air, and apparent steady-state levels were reached 5 to 8 months after building completion, a particularly striking finding given that the building was constructed and furnished several years after the voluntary phase-out of the penta- and octa-mixtures. Airborne particulate matter collected in a building's HVAC system filters contained PBDEs, including BDE-209, at levels exceeding the concentration of floor dust. In conjunction with estimates of building air flow rates, filter efficiency and other parameters, mass balance calculations for this building were used to estimate the emission rates and reservoirs of PBDEs. The widespread distribution of BFRs found in offices in both new and old buildings suggests the significance of workplace exposures, the need for controls to minimize human exposure, intra-building migration, and environmental releases of these chemicals, and the need for monitoring in new buildings to confirm the effectiveness of the PBDE phase-out. Keywords: Air exchange rate, Buildings, Brominated flame retardants, Exposure, Filters, Indoor air quality, Indoor air, PBDE

Objectives: An increasing number of complaints related to time spent in artificially ventilated buildings have been progressively reported and attributed, at least in part, to physical and chemical exposures in the office environment. The objective of this research was to investigate the association between the prevalence of work-related symptoms and the indoor air quality, comparing a sealed office building with a naturally ventilated one, considering, specially, the indoor concentration of TPM, TVOCs and the main individual VOCs. Methods: A cross-sectional study was performed to compare the prevalence of sick building syndrome (SBS) symptoms among 1736 office workers of a sealed office building and 950 of a non-sealed one, both in Rio de Janeiro's downtown. The prevalence of symptoms was obtained by a SBS standardized questionnaire. The IAQ of the buildings was evaluated through specific methods, to determine the temperature, humidity, particulate matter and volatile organic compound (VOC) concentrations. Results: Upper airways and ophthalmic symptoms, tiredness and headache were highly prevalent in both buildings. Some symptoms were more prevalent in the sealed building: “eye dryness” 33.3% and 27.1% (p: 0.01); “runny nose” 37.3% and 31.3% (p: 0.03); “dry throat” 42% and 36% (p: 0.02); and “lethargy” 58.5% and 50.5% (p: 0.03) respectively. However, relative humidity and indoor total particulate matter (TPM) concentration as well as total volatile organic compounds (TVOCs) were paradoxically greater in the non-sealed building, in which aromatic compounds had higher concentration, especially benzene. The analysis between measured exposure levels and resulting symptoms showed no association among its prevalence and TPM, TVOCs, benzene or toluene concentration in none of the buildings. Conclusions: Other disregarded factors, like undetected VOCs, mites, molds and endotoxin concentrations, may be associated to the greater prevalence of symptoms in the sealed building. Keywords: Sick building syndrome, Respiratory symptoms, Air quality, Indoor pollution, VOCs

This study was performed to investigate the concentration of PM(10) and PM(2.5) inside trains and platforms on subway lines 1, 2, 4 and 5 in Seoul, KOREA. PM(10), PM(2.5), carbon dioxide (CO(2)) and carbon monoxide (CO) were monitored using real-time monitoring instruments in the afternoons (between 13:00 and 16:00). The concentrations of PM(10) and PM(2.5) inside trains were significantly higher than those measured on platforms and in ambient air reported by the Korea Ministry of Environment (Korea MOE). This study found that PM(10) levels inside subway lines 1, 2 and 4 exceeded the Korea indoor air quality (Korea IAQ) standard of 150 microg/m(3). The average percentage that exceeded the PM(10) standard was 83.3% on line 1, 37.9% on line 2 and 63.1% on line 4, respectively. PM(2.5) concentration ranged from 77.7 microg/m(3) to 158.2 microg/m(3), which were found to be much higher than the ambient air PM(2.5) standard promulgated by United States Environmental Protection Agency (US-EPA) (24 h arithmetic mean: 65 microg/m(3)). The reason for interior PM(10) and PM(2.5) being higher than those on platforms is due to subway trains in Korea not having mechanical ventilation systems to supply fresh air inside the train. This assumption was supported by the CO(2) concentration results monitored in tube of subway that ranged from 1153 ppm to 3377 ppm. The percentage of PM(2.5) in PM(10) was 86.2% on platforms, 81.7% inside trains, 80.2% underground and 90.2% at ground track. These results indicated that fine particles (PM(2.5)) accounted for most of PM(10) and polluted subway air. GLM statistical analysis indicated that two factors related to monitoring locations (underground and ground or inside trains and on platforms) significantly influence PM(10) (p

According to the World Health Organization (WHO), indoor air pollution (IAP) from the use of solid fuels in households in the developing world is responsible for more than 1.6 million premature deaths each year, whereof 0.42 million occur in China alone. We argue that the methodology applied by WHO – the so-called fuel-based approach – underestimates the health effects, and suggest an alternative method. Combining exposure–response functions and current mortality and morbidity rates, we estimate the burden of disease of IAP in China and the impacts of three abatement scenarios. Using linear exposure–response functions, we find that 3.5 [0.8–14.7 95% CI] million people die prematurely due to IAP in China each year. The central estimate constitutes 47% of all deaths in China. We find that modest changes in the use of cooking fuels in rural households might have a large health impact, reducing annual mortality by 0.63 [0.1–3. 2 95% CI] million. If the indoor air quality (IAQ) standard set by the Chinese government (150 μg PM10/m3) was met in all households, we estimate that 0.9 [0.2–4.8] million premature deaths would be avoided in urban areas and 2.8 [0.7–12.4] million in rural areas. However, in urban areas this would require improvements to the outdoor air quality in addition to a complete fuel switch to clean fuels in households. We estimate that a fuel switch in urban China could prevent 0.7 [0.2–4.8] million premature deaths. The methodology for exposure assessment applied here is probably more realistic than the fuel-based approach; however, the use of linear exposure–response relationships most likely tends to overestimate the effects. The discrepancies between our results and the WHO estimates is probably also explained by our use of “all-cause mortality” which includes important causes of death like cardiovascular diseases, conditions known to be closely associated with exposure to particulate pollution, whereas the WHO estimate is limited to respiratory diseases. Keywords: Indoor air pollution, Rural, Urban, Exposure, China, Solid fuels, Health

Volatile organic compounds (VOCs) are the major pollutants in indoor air, which significantly impact indoor air quality and thus influencing human health. A long-term exposure to VOCs will be detrimental to human health causing sick building syndrome (SBS). Photocatalytic oxidation of VOCs is a cost-effective technology for VOCs removal compared with adsorption, biofiltration, or thermal catalysis. In this paper, we review the current exposure level of VOCs in various indoor environment and state of the art technology for photocatalytic oxidation of VOCs from indoor air. The concentrations and emission rates of commonly occurring VOCs in indoor air are presented. The effective catalyst systems, under UV and visible light, are discussed and the kinetics of photocatalytic oxidation is also presented. Keywords: Photocatalytic oxidation, Volatile organic compounds, Indoor air, UV–vis light

In contrast to a majority of reported damage-cost literature being focused on outdoor pollution, this paper describes the development of a protocol that links population exposure data with reported epidemiological concentration-response coefficients. A change in indoor particulate level is expressed as a change in total exposure levels, which is then linked with a corresponding change in ambient particulate concentrations before evaluating the associated health benefits. In this study, the development of protocol is illustrated by using a typical office building environment and daily time activity patterns of office occupants in Hong Kong. Our results indicate that some benefit gains for the owners-employers and the society would be anticipated if certain filter set configurations had been adopted. However, the amount of benefit gains for the owners-employers is shown to be increased with the average salary level of employees and the duration of their stay in offices. Keywords: Indoor air quality, Exposures, Economic valuation, Offices, Time activity

Addition of urea-based antifreeze admixtures during cement mixing can make it possible to produce concrete cement in construction of buildings in cold weather; this, however, has led to increasing indoor air pollution due to continuous transformation and emission from urea to gaseous ammonia in indoor concrete wall. It is believed that ammonia is harmful to human body and exposure to ammonia can cause some serious symptoms such as headaches, burns, and even permanent damage to the eyes and lungs. In order to understand the emission of ammonia from indoor concrete wall in civil building and assess the health risk of people living in these buildings, the experimental pieces of concrete wall were first prepared by concreting cement and urea-based antifreeze admixtures to simulate the indoor wall in civil building in this work. Then environmental chamber was adopted for studying the effect of temperature, relative humility and air exchange rate on emission of ammonia from experimental pieces of concrete wall. Also the field experiment was made at selected rooms in given civil buildings. Exposure and potential dose of adult and children exposed to indoor/outdoor ammonia in summer and in winter are calculated and evaluated by using Scenario Evaluation Approach. The results indicated that high air exchange rate leads to decreased ammonia concentration, and elevation of temperature causes increasing ammonia concentration and volatilizing rate in chamber. The complete emission of ammonia from the wall containing urea-based antifreeze admixtures needs more than 10 years in general. Ventilating or improving air exchange can play a significant role in reducing ammonia concentration in actual rooms in field experiments. Urea-based antifreeze admixtures in concrete wall can give rise to high exposure and potential dose, especially in summer. Generally, adults have a high potential dose than children, while children have personal average dose rate beyond adults in the same conditions. Keywords: Ammonia, Concrete, Emission, Chamber, Exposure, Potential dose

The cabin of an automobile can be considered to be a part of the living environment because many people spend long periods of time during business, shopping, recreation or travel activities. However, little is known about the interior air contamination due to organic compounds diffusing from the interior materials used in the interior of automobiles. In the present study, the compounds in the interior air of a new car were identified, and the time courses of their concentrations were examined for over 3 years after the delivery (July, 1999). A total of 162 organic compounds, involving many aliphatic hydrocarbons and aromatic hydrocarbons, were identified. High concentrations of n-nonane (458 μg/m3 on the day following delivery), n-decane (1301 μg/m3), n-undecane (1616 μg/m3), n-dodecane (716 μg/m3), n-tridecane (320 μg/m3), 1-hexadecene (768 μg/m3), ethylbenzene (361 μg/m3), xylene (4003 μg/m3) and 2,2′-azobis(isobutyronitrile) (429 μg/m3) were detected, and the sum of the concentrations determined for all compounds excluding formaldehyde (TVOC) was approximately 14 mg/m3 on the day after the delivery. The concentrations of most compounds decreased with time, but increased with a rise of the interior temperature. The TVOC concentration in the next summer (July, 2000) was approximately one-tenth of the initial concentration. During the 3-year study period, the TVOC concentrations in summer exceeded the indoor guideline value (300 μg/m3) proposed by Seifert (1995) [Seifert B. Volatile organic compounds. In: Maroni M, Seifert B, Lindvall T, editors. Indoor air quality. A comprehensive reference book. Air quality monographs, vol. 3. Netherlands: Elsevier Science; 1995. p. 819–21]. The interior temperature and days lapsed after delivery were the main factors affecting the interior concentrations of most compounds according to multiple linear regression analysis. The results of this study offer useful fundamental data for investigations on air pollution in automotive cabins due to the organic compounds diffusing from the interior materials. Keywords: Interior temperature, Interior humidity, Number of lapsed days, Multiple linear regression analysis, Indoor air pollution

The indoor air quality (IAQ) at six residential buildings in Hong Kong was investigated based on different locations and characteristics. IAQ parameters measured from October 1997 to January 1998 included temperature, relative humidity, CO2, PM10, HCHO, bacteria, SO2, NO, NO2, and CO. CO2, PM10, and HCHO were monitored for a 24-h period, and other IAQ pollutants were monitored continuously. IAQ pollutants at the six sites were below the Hong Kong Interim IAQ Guidelines except for PM10 and bacteria levels. Sites where tobacco smoking is permitted had the worst IAQ. During smoking, PM10 levels were as high as 2153 μg/m3. All sites had bacteria levels below the recommended action level of 1000 CFU/m3. Three sites (North Point, Ngau Tau Kok, and Prince Edward), with relatively high bacteria levels, were buildings over 20 y old. Maximum CO2 levels detected were as high as 2.63 mL/L due to poor ventilation. The results indicated that IAQ at residential areas in Hong Kong should be constantly monitored and improved.

Research on air pollution and behavior has shifted from studies that examined the relationship between outdoor contaminants and behavior to studies on malodor and indoor air pollution. This shift increases the relevance of laboratory experiments that examined the effects of malodor on social behavior. A review of results from laboratory and field studies on the social consequences of air pollution suggests several opportunities for those doing research on the sick building syndrome (SBS). It is proposed that the social consequences of the SBS may be as important and costly as physical symptoms.

High carbon monoxide and nitrogen dioxide concentrations were measured in an indoor ice-skating rink with fuel-powered ice-resurfacing equipment. In 22% to 33% of the measurements over 90-min segments, CO concentrations exceeded 20 [mu]L/L as a 90-min average in the absence of rink ventilation. Average NO[sub 2] concentrations over 14 h were higher than 600 nL/L. Reduction of air pollutant concentrations in the ice-skating rink is necessary to prevent air-pollutant-exposure-related health incidents. Various methods for reducing air pollutants in an ice-skating rink were evaluated by simultaneously measuring CO and NO[sub 2] concentrations. Single pollution reduction attempts, such as extension of the exhaust pipe, reduction in the number of resurfacer operations, or use of an air recirculation system, did not significantly reduce air pollutant concentrations in the rink. Full operation of the mechanical ventilation system combined with reduced resurfacer operation was required to keep the air pollutant levels in the skating rink below the recommended guidelines. This investigation showed that management of clean air quality in an ice-skating rink is practically difficult as long as fuel-powered resurfacing equipment is used. 16 refs., 3 figs., 5 tabs.

The lead, zinc, cadmium, chromium, and nickel contents in both indoor house dust and outdoor street dust from 76 sites in Bahrain were determined by ICP-ES. The results showed widespread heavy metal contamination, especially lead, with an overall mean value in house dust for Pb, Zn, Cd, Cr, and Ni of 517, 202, 1.9, 11, and 10, respectively. The mean values in street dust were 742, 67, 1.5, 9.6, and 12 mg/kg, respectively. The major source of metals in street dust was automobile exhaust. The major source of heavy metals indoors was also from automobile dust, i.e., lead and nickel. With respect to zinc, cadmium, and chromium, indoor sources were more important than outdoor sources. The distribution of lead both indoors and outdoors in Bahrain showed high levels of contamination occurring generally in the north and northeastern part where traffic is concentrated. The levels of these toxic metals found in indoor house dust may be a significant source of exposure, especially for children.

Burning candles and incense generate particulate matter (PM) that produces poor indoor air quality and may cause human pulmonary problems. This study physically characterised combustion particles collected in a church during services. In addition, the emissions from five types of candles and two types of incense were investigated using a combustion chamber. The plasmid scission assay was used to determine the oxidative capacities of these church particles. The corresponding risk factor (CRf) was derived from the emission factor (Ef) and the oxidative DNA damage, and used to evaluate the relative respiratory exposure risks. Real-time PM measurements in the church during candle–incense burning services showed that the levels (91.6 μg/m3 for PM10; 38.9 μg/m3 for PM2.5) exceeded the European Union (EU) air quality guidelines. The combustion chamber testing, using the same environmental conditions, showed that the incense Ef for both PM10 (490.6–587.9 mg/g) and PM2.5 (290.1–417.2 mg/g) exceeded that of candles; particularly the PM2.5 emissions. These CRf results suggested that the exposure to significant amounts of incense PM could result in a higher risk of oxidative DNA adducts (27.4–32.8 times) than tobacco PM. The generation and subsequent inhalation of PM during church activities may therefore pose significant risks in terms of respiratory health effects. Keywords: Candles, Church, ETS, Incense, Particulate matter, ROS

The change in the perception of polluted air was studied during the first 15 min of exposure in climate chambers. Subjects, 16 female and 16 male, ages 18–30 y, served as air quality judges during 42 exposures. They were exposed to different concentrations of human bioeffluents (500–4000 μL/L CO 2 ), tobacco smoke (0.25–2.5 μL/L CO), and emissions from building materials (−). The subjects voted every 2 min on scales for odor intensity and acceptability of the air quality, while they were exposed to constant levels of the air pollution. Perception of bioeffluents reached a low level independent of concentration after a dew minutes. Adaptation to tobacco smoke caused acceptability to increase, but votes still depended on concentration. Ventilation for comfort may be reduced considerably if a few minutes of discomfort are acceptable or if the occupants are exposed to a gradually increased pollution level during the first 10 min or more of their stay in a space.

We have shown that formaldehyde can be removed from the air when the fibre-glass filters are coated with the polymer polyethylenimine, mixed with glycerol to keep it from hardening. By increasing the amount of polymer applied to the filter, it has been possible to extend the life of the coating to almost four months during which time the level of formaldehyde in the house is well within acceptable levels. It was also shown that in the process of air-conditioning a house or dehumidifying the air, the formation of water of condensation will remove part of the water soluble pollutants in the air.

Principal component analysis (PCA) was used to study polynuclear aromatic hydrocarbon (PAH) profiles in indoor air. Fifteen PAHs were measured in ten different homes in Columbus (Ohio) which had different indoor emission characteristics such as gas utilities, wood-burning fireplaces, and cigarette smokers. Different PAH concentration patterns emerged depending upon the emission sources present in the different homes. Of these, cigarette smoking appeared to have the greatest impact on the indoor PAH concentrations. The PCA allowed convenient displays of the multidimensional data set from which the PAH concentration characteristics could be elucidated. The interrelationship between the different PAHs was also studied by correlation analysis.

The presence of selected volatile organic compounds (VOCs) including aromatic, aliphatic compounds and low molecular weight carbonyls, and a target set of phthalates were investigated in the interior of 23 used private cars during the summer and winter. VOC concentrations often exceeded levels typically found in residential indoor air, e.g. benzene concentrations reached values of up to 149.1 µg m−3. Overall concentrations were 40% higher in summer, with temperatures inside the cars reaching up to 70 °C. The most frequently detected phthalates were di-n-butyl-phthalate and bis-(2-ethylhexyl) phthalate in concentrations ranging from 196 to 3656ngm−3. Keywords: VOC, Benzene, Plasticisers, Automobile emissions, In-vehicle exposure

The paper reports the estimates of dust fall and its chemical composition in certain indoor areas of Hyderabad - Secunderabad Railway Station and a big domestic mess. The quantity of dust fall; percentage of living matter in aerosols; and the pH, SO{sub 4}, Cl, Fe, Co, Zn, Mn, and Cu contents of dust were analyzed. The deposition of airborne dust particles was 102 to 180 mg/m{sup 2} {times} d in the railway station, while in the mess it was 52 to 97 mg/m{sup 2} {times} d.

The authors investigated indoor thermal environment, airtightness, indoor air quality, and energy consumption in thirteen new houses of wood-frame construction in a local city of Japan in the winter of 1985. All houses had thermally-insulated walls, ceilings, and floors, except for one house which had a concrete floor without insulation under the floor. Eight houses had concrete floors on the first level of the structure. Seven houses out of eight had hot-water pipes embedded in the concrete for floor heating and thermal insulation under the floor on the grade. Three houses out of seven also had fan coil units in the bedrooms on the second floor. The six other houses without floor heating had oil or gas local space heaters. The authors found differences in temperature profiles between the houses with floor heating and those with space heaters. The effective leakage area per floor area obtained by the fan pressurization method was distributed from 3.8 to 16 cm{sup 2}/m{sup 2}. The concentration measurements of CO{sub 2} and NO{sub 2} in the living rooms showed that the two houses with unvented oil space heaters were more polluted than the other houses. The total annual amount of energy consumption was distributed frommore » 46 to 100 GJ.« less