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Due to the majority of time people spent indoors, indoor air quality is not only critical to people's health, comfort, but can also significantly influence occupants perception on indoor environment. Air quality is closely related to many factors including thermal parameters, pollutant concentrations, and ventilation performance. However, the current building indoor air quality evaluation method is based the objective measurement of indoor parameters, without considering occupants' subjective perception. This paper is aimed at summarizing a profound review on the PAQ evaluation method. Comparisons among various PAQ evaluating methods with advantages, similarities and differences were conducted. Analysis of literatures about indoor air quality in Chinese residential buildings field is also summarized, and discussion on the subjective influence of temperature and relative humidity, ventilation performance, volatile organic compounds (VOCs) concentration, and particulate matters on perceived air quality is carried out. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of two circulation modes of a plasma deodorization unit on the air environment of pig-fattening houses in winter. Two pig-fattening houses were selected, one of which was installed with a plasma deodorizing device with two modes of operation, alternating internal and external circulation on a day-by-day basis. The other house did not have any form of treatment and was used as the control house. Upon installing the system, this study revealed that in the internal circulation mode, indoor temperature and humidity were sustained at elevated levels, with the NH3 and H2S concentrations decreasing by 63.87% and 100%, respectively, in comparison to the control house. Conversely, in the external circulation mode, the indoor temperature and humidity remained subdued, accompanied by a 16.43% reduction in CO2 concentration. The adept interchange between these two operational modes facilitates the regulation of indoor air quality within a secure environment. This not only effectively diminishes deleterious gases in the pig-fattening house but also achieves the remote automation of environmental monitoring and hazardous gas management; thereby, it mitigates the likelihood of diseases and minimizes breeding risks. [ABSTRACT FROM AUTHOR]

Air pollution is caused by chemical, physical, or biological components alters the fundamental properties of the atmosphere, and contaminates the interior or outdoor settings. With the rapid industrialization activity in recent years, there is an urgent need to monitor air quality. The proposed research provides a mechanism for monitoring air pollution in indoor and outdoor environments. The system consists of an IoT-based Arduino device. The Arduino IDE connects the Temperature and Humidity sensor, Grove light sensor, and air quality sensor to measure the air pollutants such as Carbon dioxide CO2, Nitrogen oxide (NOx), and Particulate Matter PM2.5. The sensors work efficiently and provide qualitative findings from the environment when they are exposed to CO2, gasoline, solvents, thinner, formaldehyde, and other harmful chemicals. The Wi-Fi module of the Blues Wireless Notehub is used for secure data routing to the IoT cloud. The Air Quality Index (AQI) measures provide information on whether there is something unsafe in indoor and outdoor environments. For collecting and analyzing the device data, the Notecard is intended to be used with a cloud storage service. Also, the indoor fire detector identifies the incident of fire intimates the users through the alarm, and measures the indoor pollutant at that time. The proposed smart IoT product model would be an excellent device for air quality monitoring because of its long-term consistency and low electricity consumption. [ABSTRACT FROM AUTHOR]

Knowledge of indoor air quality (IAQ) in cob buildings during the first few months following their delivery is of vital importance in preventing occupants' health problems. The present research focuses on evaluating IAQ in cob buildings through a prototype built in Normandy, France. To achieve this, the prototype was equipped with a set of sensors to monitor various parameters that determine indoor and outdoor air quality. These parameters include relative humidity (RH), carbon dioxide (CO2), nitrogen dioxide (NO2), ozone (O3), particulate matter (PM1 and PM10), and volatile organic compounds (VOCs). The obtained experimental results indicate that, overall, there is good indoor air quality in the prototype building. However, there are some noteworthy findings, including high indoor RH and occasional spikes in CO2, PM1, PM10, and VOCs concentrations. The high RH is believed to be a result of the ongoing drying process of the cob walls, while the peaks in pollutants are likely to be attributed to human presence and the earthen floor deterioration. To ensure consistent good air quality, this study recommends the use of a properly sized Controlled Mechanical Ventilation system. Additionally, this study explored IAQ in the cob building from a numerical perspective. A Long Short-Term Memory (LSTM) model was developed and trained to predict pollutant concentrations inside the building. A validation test was conducted on the CO2 concentration data collected on-site, and the results indicated that the LSTM model has accurately predicted the evolution of CO2 concentration within the prototype building over an extended period. [ABSTRACT FROM AUTHOR]

The quality of air conditioning and ventilation systems in laboratories is vital to ensure optimum health of the users and guarantee the accuracy of experiments conducted. Moreover, recent studies show that the average quality of air conditioning and ventilation systems in labs can pose health risks to occupants. The study aims to examine the relationship between physical parameters and microbial pollutants in research laboratories' indoor air quality (IAQ) by quantifying and characterising the bacteria and fungi in the indoor environment of research laboratories using the settle plate method; whereby our Petri dishes containing media are exposed to the air for sample collection. This study was conducted over the course of 3 ​day ​at three different research laboratories: Virology Lab (VL), Genetic Lab (GL), and Aquatic Lab (AL). The physical parameters such as air temperature, humidity and carbon dioxide were measured using FLUKE 975 air meter, whereas the microbial parameters were assessed using the settle plate method with Tryptone Soya agar and Sabouraud Dextrose agar for the bacterial and fungal count, respectively. Our results showed that the high temperature and relative humidity, exceeded the standard threshold for temperature (23–26 ​°C) and relative humidity (40–70%) set by the Department of Occupational Safety and Health (DOSH). Additionally, because of poor air conditioning and ventilation system maintenance, there were high total bacterial counts in GL (CFU/m³ 234.34 ​± ​30.93) and total fungal counts in VL (CFU/m³ 589.34 ​± ​53.03). We also showed that the most commonly isolated bacteria and fungi in research laboratories were Staphylococcus spp. (72.2%) and Cladosporium spp. (76.7%). In conclusion, we reported that there was a correlation between the physical parameters and microbial pollutants in the research laboratories. Therefore, regular monitoring of indoor air quality (IAQ) parameters and maintenance of the air conditioning and ventilation system should be carried out to ensure a good and safe indoor environment in research laboratories. [ABSTRACT FROM AUTHOR]

People tend to spend considerable amounts of time in buildings; thus the issue of providing proper indoor environmental quality is of significant importance. This paper experimentally analyses the subjective sensations of the occupants of intelligent and traditional buildings with the focus on possible differences between these two types of buildings. The study is based on a large database of 1302 questionnaires collected in 92 rooms where simultaneous measurements of the indoor environment physical parameters (air and globe temperature, relative humidity, carbon dioxide concentration, and illuminance) were carried out. Their impact on the subjective assessment of the indoor environment has been presented and analysed. The results show that the occupants seemed to be more favourable towards the indoor conditions in the intelligent building; however, the differences in comparison to the traditional buildings were not considerable. Similarly, self-reported productivity proved to be higher in the intelligent building, while the optimal range of air temperature, which ensured highest productivity, was 22–25 °C. Moreover, a strong correlation between the occupants' overall comfort and their perception of the air quality has been found. [ABSTRACT FROM AUTHOR]

People spend most of their time in indoor environments without knowing about the air quality in these spaces. In this study, indoor low-cost sensors were used (for 5 months) to assess the comfort and air quality patterns in two indoor households. To strengthen the robustness of the considered approach and build confidence in the obtained comfort and indoor air quality (IAQ) levels, the sensor measurements were also compared against information from reference monitoring equipment; in which, high correlation coefficients were obtained (> 0.85) and also low errors (on average 22%). The IAQ results were strongly influenced by the residents' activity and behaviour, the outdoor weather conditions, and indoor/outdoor air pollution sources. Overall, the recommended values of temperature and relative humidity for the occupant's comfort in indoor environments were not fulfilled. The highest particulate matter (PM) levels were recorded at the weekend (on average +14% higher), while maximum CO2 and CO levels were obtained on the weekdays (on average +9% higher). PM daily profiles followed the outdoor concentrations with the maximum levels at the end of the night and the lowest values in the early morning/mid-afternoon. The highest and lowest CO2 concentrations were registered in the early morning (< 1536 ppm) and mid-afternoon (< 627 ppm), respectively, while the CO daily profiles showed a high impact of outdoor emissions, with the minimum concentrations up to 0.81 mg m−3 (at 10 a.m. or 6 p.m.), and a maximum concentration of 1.87 mg m−3 (at 10 p.m.). Real-time comfort conditions and IAQ levels are a powerful approach to providing fast decisions to minimise human exposure and prevent negative health impacts. [ABSTRACT FROM AUTHOR]

The article presents the results of measurements of temperature, relative humidity and CO2 concentration in six single-family houses' bedrooms located in Poland, in Wrocław and vicinity, during two climatic seasons: summer–autumn and winter. Two buildings with natural ventilation (NV) were tested, three with mechanical ventilation with heat recovery (MV) and one with hybrid ventilation (HV)—mixed mode natural and mechanical. The behavior of residents regarding opening windows was analyzed and the influence of the changing internal and external conditions on their active reactions was examined. The analysis confirms and adds to the global discourse on the key impact of user behavior on securing healthy indoor air quality in housing, regardless of ventilation system or building energy standard. A disconnect exists between the observed window opening practices and typical design principles, assuming adjustment to a given ventilation system or changing weather conditions. The observations showed that in both analyzed seasons it was possible to obtain a good quality internal environment, in terms of CO2 level, regardless of the ventilation system used in the building. However, unfavorable results were observed for one bedroom, in which the inhabitants do not adapt their behavior to local technical conditions. Taking into account the level of relative humidity (RH), much higher values were observed in the NV bedrooms in both analyzed periods. The obtained results were divided into IAQ classes in accordance with the EN 16798-1. The recorded values of the internal temperature confirm the significant influence of the location of the room in the building and the actions taken by the residents. [ABSTRACT FROM AUTHOR]

Simple Summary: Indoor air quality is strongly associated with animal health and wellbeing. Therefore, animal enclosures must be consistently and sufficiently ventilated to provide for the health and well-being of animals and caretakers. Although there are several publications concerning assessments and effects of suboptimal air quality on rodents, no publications are available on group-housed non-human primates and the exposure of caretakers to inhalable dust and endotoxins. The indoor air quality of group-housed macaques at the Biomedical Primate Research Center (Rijswijk, the Netherlands) was assessed to identify possible problems regarding air circulation and the concentrations of inhalable dust, endotoxin, ammonia, fungi, temperature and relative humidity in the indoor environment. In addition, the exposure to inhalable dust and endotoxins of caretakers was evaluated. The observed values for these air quality parameters, measured at fixed locations in the animal enclosures, did not exceed the proposed human threshold limit values (TLV). However, caretakers were exposed to higher levels than the animals likely due to nature of their tasks. This study provides practical tools that can be used to improve the indoor air quality in group-housed macaques. Moreover, the results show that the exposure of caretakers to inhalable dust and endotoxins during daily work routines should be reduced. Indoor Air Quality (IAQ) is strongly associated with animal health and wellbeing. To identify possible problems of the indoor environment of macaques (Macaca spp.), we assessed the IAQ. The temperature (°C), relative humidity (%) and concentrations of inhalable dust (mg/m3), endotoxins (EU/m3), ammonia (ppm) and fungal aerosols were measured at stationary fixed locations in indoor enclosures of group-housed rhesus (Macaca mulatta) and cynomolgus macaques (Macaca fascicularis). In addition, the personal exposure of caretakers to inhalable dust and endotoxins was measured and evaluated. Furthermore, the air circulation was assessed with non-toxic smoke, and the number of times the macaques sneezed was recorded. The indoor temperature and relative humidity for both species were within comfortable ranges. The geometric mean (GM) ammonia, dust and endotoxin concentrations were 1.84 and 0.58 ppm, 0.07 and 0.07 mg/m3, and 24.8 and 6.44 EU/m3 in the rhesus and cynomolgus macaque units, respectively. The GM dust concentrations were significantly higher during the daytime than during the nighttime. Airborne fungi ranged between 425 and 1877 CFU/m3. Personal measurements on the caretakers showed GM dust and endotoxin concentrations of 4.2 mg/m3 and 439.0 EU/m3, respectively. The number of sneezes and the IAQ parameters were not correlated. The smoke test revealed a suboptimal air flow pattern. Although the dust, endotoxins and ammonia were revealed to be within accepted human threshold limit values (TLV), caretakers were exposed to dust and endotoxin levels exceeding existing occupational reference values. [ABSTRACT FROM AUTHOR]

Taiwan is located in a subtropical region with high temperatures and humidity. Office spaces are located in air-enclosed rooms in buildings, where doors and windows remain closed and only a central air-conditioning system provides temperature adjustment and ventilation. Most offices in this area have office seating areas, document storage areas on both sides of the office, and multi-function devices, which can cause sick office syndrome in the employees. This study applied environmental monitoring technology to analyze the architectural form and indoor and outdoor air quality to propose improvement strategies addressing indoor temperature, relative humidity and air quality. Quality indices were used created to evaluate the improvement efficiency. The analysis results showed that the indoor temperature and relative humidity in staff seating areas can be effectively improved. The statistical analysis results of improved efficiency for PM2.5, PM10 concentrations and total suspended particulates showed that the average indicator values have been raised from 0.05 to 1.5, 2.45 to 4.02 and 0.91 to 3.54, respectively, for staff seating area and −0.01 to 2.82, 0.15 to 3.91 and 1.25 to 7.25, respectively, for photocopier areas. The ambient air quality of this office space has been significantly improved. This study can serve as an example of air quality improvement in traditional common office spaces. [ABSTRACT FROM AUTHOR]

Since people spend most of their time in indoor environments, the objective of this work was to study indoor air quality and its effects on users’ thermal comfort. Based on previous data from a building with a central air-conditioning system and two mixed-mode buildings located in the humid subtropical climate of Florianópolis, southern Brazil, statistical analyses were performed. Each user’s subjective answer obtained through a questionnaire was combined with the corresponding environmental conditions measured by instruments. Results showed that improvement in air quality was associated with the reduction of air temperature and humidity ratio. Also, there was a significant influence of thermal and humidity sensation on air quality satisfaction. Users felt more satisfied or neutral with air quality for being in thermal comfort, and not because of the CO2 concentration—which means that air quality perception is influenced by factors other than CO2. This study recommends implementing an air exchange device in split air-conditioners with air recirculation commonly used in mixed-mode buildings in Brazil. It is important to provide suitable indoor ventilation to reduce pollutant concentration, ensure good air quality and prevent respiratory diseases. [ABSTRACT FROM AUTHOR]

No study has comprehensively reviewed the effects of indoor plants on air quality; therefore, this study systematically reviewed quantitative empirical research on these effects in both English and Chinese. The information sources were the Web of Science and WanFang Data Knowledge Service Platform electronic databases. Only journal articles reporting quantitative empirical research were selected. The eligibility criteria included studies with (1) interventions of any indoor plant, excluding biofilters that combine power facilities and vegetation, (2) comparators included within the same experimental treatment or between different experimental treatments, (3) air quality effects objectively measured using any instrument, and (4) any study design. Both authors screened 95 journal articles and compiled information according to (1) intervention (plant species, foliage, or medium), (2) scientific family name of each plant, (3) study design (experiment, field experiment, or survey), (4) air quality (e.g., temperature, humidity, negative ions, radiation, and dust), (5) pollutants, (6) research environment, (7) ventilation (types and rates), (8) climate (lighting, temperature, and humidity), (9) exposure duration, (10) sampling frequency or period, and (11) number of replications. The primary effects of the potential of the indoor plants on air quality were reduced pollutant levels (particularly formaldehyde, benzene, and toluene removal), followed by increase in humidity and decrease in temperature. In addition, including various plant species could improve the effects of indoor vegetation on ameliorating air quality and microclimate conditions. [ABSTRACT FROM AUTHOR]

• Indoor environmental quality (IEQ) in low-income flats. • Occupants have an influence on air quality. • Variability in window opening routines and natural ventilation intervals. • Observed outcome was poor quality and often unhealthy indoor air. Thermal comfort and Indoor air quality (IAQ) in residential buildings with different degrees of airtightness was studied in two climates in Spain. Behaviour was compared in the areas occupied by day and by night. The IAQ of the buildings studied, erected before energy efficiency regulations were in place (1939–79) and lacking mechanical ventilation, was compared to their airtightness. The rationale for that approach was that under such circumstances air change depends on uncontrolled natural ventilation (=opening windows) and consequently on the outdoor temperature. Relative humidity was also taken into consideration, given the condensation that may be induced where ventilation is insufficient. In winter in both climates, the CO 2 levels were over 1200 ppm, with means on the order of 1900 ppm in Madrid and 1400 ppm in Seville and higher at night than during the day. Infiltration-mediated air changes/hour appeared to be insufficient to maintain the house under healthy conditions and the risk of surface condensation is higher in the most airtight dwellings. [ABSTRACT FROM AUTHOR]

Byline: Sonal. Gawande, Rajnarayan. Tiwari, Prakash. Narayanan, Ashwin. Bhadri Indoor air quality (IAQ) influences human health, productivity and wellness. Green buildings are believed to have better IAQ. The 'sick building [...]

It is generally assumed that vertical pollutant dispersion can reduce exposures to ambient pollutants in tall buildings, as concentrations of some ground-source pollutants are diluted at higher floors. However, we are aware of very few measurements of airborne pollutant concentrations that have been made specifically along the height of tall buildings. Therefore, we conducted a pilot study to measure the vertical variation in the concentrations of several outdoor pollutants and environmental parameters along the height of a ∼60-story (∼300 m) building in downtown Chicago, IL during a one-week period in the summer of 2017. Simultaneous measurements of concentrations of size-resolved particulate matter 0.3–10 μm (which were also used to estimate PM 1 , PM 2.5 , and PM 10 mass concentrations), ozone (O 3 ), nitrogen dioxide (NO 2 ), carbon dioxide (CO 2 ), and carbon monoxide (CO), as well as temperature and relative humidity, were made using multiple sets of instrumentation installed in the outdoor air intakes of the mechanical systems upstream of any filtration or mixing processes on the 2nd, 16th, 29th, and 44th floors and in an open-air area on the 61st floor. The average PM 1 and PM 2.5 concentrations estimated on the top two floors were more than 30% lower than on the 2nd floor. Temperature, humidity ratio, and CO 2 concentrations decreased with height, O 3 concentrations increased with height, and NO 2 concentrations were less consistent. Most of the differences between floors were statistically significant. Floor height was more strongly correlated with PM 1 , PM 2.5 , PM 10 , CO 2 , and O 3 concentrations than with local wind speed and direction. [ABSTRACT FROM AUTHOR]

There is a long-standing dispute about indoor air humidity and perceived indoor air quality (IAQ) and associated health effects. Complaints about sensory irritation in eyes and upper airways are generally among top-two symptoms together with the perception "dry air" in office environments. This calls for an integrated analysis of indoor air humidity and eye and airway health effects. This overview has reviewed the literature about the effects of extended exposure to low humidity on perceived IAQ, sensory irritation symptoms in eyes and airways, work performance, sleep quality, virus survival, and voice disruption. Elevation of the indoor air humidity may positively impact perceived IAQ, eye symptomatology, and possibly work performance in the office environment; however, mice inhalation studies do not show exacerbation of sensory irritation in the airways by low humidity. Elevated humidified indoor air appears to reduce nasal symptoms in patients suffering from obstructive apnea syndrome, while no clear improvement on voice production has been identified, except for those with vocal fatigue. Both low and high RH, and perhaps even better absolute humidity (water vapor), favors transmission and survival of influenza virus in many studies, but the relationship between temperature, humidity, and the virus and aerosol dynamics is complex, which in the end depends on the individual virus type and its physical/chemical properties. Dry and humid air perception continues to be reported in offices and in residential areas, despite the IAQ parameter "dry air" (or "wet/humid air") is semantically misleading, because a sensory organ for humidity is non-existing in humans. This IAQ parameter appears to reflect different perceptions among other odor, dustiness, and possibly exacerbated by desiccation effect of low air humidity. It is salient to distinguish between indoor air humidity (relative or absolute) near the breathing and ocular zone and phenomena caused by moisture-damage of the building construction and emissions therefrom. Further, residential versus public environments should be considered as separate entities with different characteristics and demands of humidity. Research is needed about particle, bacteria and virus dynamics indoors for improvement of quality of life and with more focus on the impact of absolute humidity. "Dry (or wet) air" should be redefined to become a meaningful IAQ descriptor. [ABSTRACT FROM AUTHOR]

Pig manure contains a wide variety of corrosion-inducing chemicals such as ammonia. Ammonia production and its release are influenced by temperature and moisture in the barn environment. Increased concentrations of ammonia can negatively affect pig health and growth, as well as pose a risk to human health. Additionally, even at decreased concentrations, ammonia reacts with humidity and causes premature corrosion of barn equipment and is a threat to the structural integrity of livestock buildings. In this study, ammonia concentrations were monitored and compared between two 880 head wean-finish swine facilities with different types of waste management systems. Both facilities had shallow manure pits, one containing a flush system and one containing a pull plug system to remove manure from the barns into the lagoon. Ammonia, dry-bulb air temperature, and relative humidity levels were measured every0 min for an entire wean-finish cycle (approximately 20 weeks). Data will be compared between the facilities to evaluate the impact of the waste management systems on indoor air quality conditions. Potential implications for pig health and growth and facility maintenance will be explored. Results will provide information on best management strategies for swine facilities. [ABSTRACT FROM AUTHOR]

This study investigates the influence of three environmental indoor parameters (i.e., temperature, relative humidity, and air exchange rate) on the emission of 13 volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) during incense burning. Experiments have been carried out using an environmental test chamber. Statistical results from a classical two-level full factorial design highlight the predominant effect of ventilation on emission factors. The higher the ventilation, the higher the emission factor. Moreover, thanks to these results, an estimation of the concentration range for the compounds under study can be calculated and allows a quick look of indoor pollution induced by incense combustion. Carcinogenic substances (i.e., benzene, benzo(a)pyrene, and formaldehyde) produced from the incense combustion would be predicted in typical living indoors conditions to reach instantaneous concentration levels close to or higher than air quality exposure threshold values. [ABSTRACT FROM AUTHOR]

Previous studies have shown that poorly ventilated classrooms can have negative impact on the health of children and school staff. In most cases, schools in Serbia are ventilated naturally. Considering their high occupancy, classroom air quality test determines the level of air pollution, after which it is possible to implement corrective measures. The research presented in this study, was conducted in four schools which are located in different areas and have different architecture designs. Measurements in these schools have been performed during the winter (heating season) and spring (non-heating season) and the following results were presented: indoor air temperature, relative humidity, and carbon dioxide concentration. These results show that the classroom average concentration of carbon dioxide often exceeds the value of 1500 ppm, during its full occupancy, which indicates inadequate ventilation. Measurement campaigns show that carbon dioxide concentration increased significantly from non-heating to heating season in three of the four schools. Analysis of measurements also determined high correlation between relative humidity and carbon dioxide concentration in all schools in winter season. This fact may constitute a solid basis for the fresh air supply strategy. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) may be emitted from surfaces indoors leading to compromised air quality. This study scrutinized the influence of relative humidity (RH) on VOC concentrations in a building that had been subjected to water damage. While air samplings in a damp room at low RH (21-22 %) only revealed minor amounts of 2-ethylhexanol (3 μg/m) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB, 8 μg/m), measurements performed after a rapid increase of RH (to 58-75 %) revealed an increase in VOC concentrations which was 3-fold for 2-ethylhexanol and 2-fold for TXIB. Similar VOC emission patterns were found in laboratory analyses of moisture-affected and laboratory-contaminated building materials. This study demonstrates the importance of monitoring RH when sampling indoor air for VOCs in order to avoid misleading conclusions from the analytical results. [ABSTRACT FROM AUTHOR]

Considering that air conditioning is widely applied for improving human standard of living, this present investigation is focused on the optimization of indoor air quality characteristics of air-conditioned cars using the Gray relational analysis (GRA) and the response surface methodology (RSM). The air-conditioned space is selected and the experiments are planned as per experimental design to study the effects of human load, fresh air supply, and air velocity on human comfort conditions. Mathematical models are developed to predict the comfort conditions, namely temperature, CO level, and relative humidity over a specified range of input conditions. The optimum values of comfort conditions for varying input conditions are found by assigning weightages to individual responses using GRA and RSM. [ABSTRACT FROM AUTHOR]

The present investigation was focused on the analysis of indoor air quality characteristics of an air conditioned car using statistical approach. The conditioned space was selected and the experiments were planned as per design of experiments to study the effect of human load, fresh air supply and air velocity on the human comfort conditions. The nonlinear regression models were developed to predict the comfort conditions namely temperature, CO2 level and relative humidity over a specified range of input conditions in this investigation. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to collect data on some of the factors that contribute to indoor air quality and to discomfort, in order to take the proper actions that can reduce the level of air pollution within houses and offices. To ascertain the contamination degree total bacterial counts, total fungal counts, suspended particulate matter, air temperature, and relative humidity have been determined. Additionally, mathematical statistical models have been elaborated for the total bacterial count, respirable particulate matter and humidity. A total number of 40 indoor air samples were collected from office and houses. The results shows that approximately 45% of the air samples from homes, and 45% of the air samples from offices had levels of total viable count higher than the recommended by “European Concerted Action—Indoor Air Quality and Its Impact on Man– Report No 12.” For yeast and moulds it was observed that 40% of the air samples within homes, and 10% of the air samples within offices had levels of total viable count higher than the recommended. This highlights the need for frequent cleaning of offices and homes as well as the ventilation improvement for providing a healthy environment. [ABSTRACT FROM AUTHOR]

Air pollution surveys of formaldehyde (HCHO) were conducted in 2324 rooms decorated within one year in 2007-2009 in Hangzhou, China. The mean HCHO concentration (CHCHO) was 0.107 ± 0.095 mg/m³ and 38.9% of samples exceeded the Chinese National Standard GB 50325-2010. Over the past 3 years, the CHCHO decreased with time (p < 0.05). Relationships of potential factors to indoor CHCHO were also evaluated. CHCHO was related to temperature (T), relative humidity (RH), time duration of the windows and doors being closed before sampling (DC), time duration from the end of decoration to sampling (DR) and source characteristics (d). A model to relate indoor CHCHO to these five factors (T, RH, DC, DR, d) was established based on 298 samples (R² = 0.87). Various factors contributed to CHCHO in the following order: T, 43.7%; d, 31.0%; DC, 10.2%; DR, 8.0%; RH, 7.0%; specifically, meteorological conditions (i.e., RH plus T) accounted for 50.7%. The coefficient of T and RH, R-m, was proposed to describe their combined influence on HCHO emission, which also had a linear relationship (R² = 0.9387) with HCHO release in a simulation chamber test. In addition, experiments confirm that it is a synergistic action as 7 and RH accelerate the release of HCHO, and that is a significant factor influencing indoor HCHO pollution. These achievements could lead to reference values of measures for the efficient reduction of indoor HCHO pollution. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a practical investigation into the indoor air quality of a fully air-conditioned eight-storey healthcare facility in the East Malaysia region before and after vapour decontamination. East Malaysia is located in a hot and humid climate, which favours the growth of bacteria, yeasts and moulds. The main purpose of the investigation is to identify the potential of tea tree oil vapour decontamination to improve the indoor air quality by reducing the active bacteria, yeast and mould concentrations in indoor air. A total of 336 samples have been taken inside the building for indoor air at 84 different locations and 24 samples have been taken for outdoor air at 12 locations, which are near the fresh air intakes of the air handling units. The vapour decontamination method is used in the present study. Results show that the humidity levels remain high during the entire study period, exceeding 60% relative humidity, favouring the growth of bacteria, yeasts and moulds. By applying vapour decontamination from the air handling units to the ventilated air serving areas, the average bacteria, yeast and mould count is successfully reduced to below the recommended threshold of 500 CFU m−3 for normal zones, and 35 CFU m−3 for critical zones. The decontamination study result strongly suggests that the very real potential for applying tea tree oil vapour as air treatment in tropical countries like Malaysia for indoor air quality management in healthcare facilities. [Copyright &y& Elsevier]

The indoor total volatile organic compound (TVOC) concentrations and their relationship to potential influencing factors were evaluated. Samples ( n = 2302) were collected from 2007 to 2009 both in old structures and new construction in the city of Hangzhou from bedrooms, sitting rooms and studies that had been decorated within the previous year. The average TVOC concentration in all the newly decorated rooms was 0.65±0.69 mg/m. 35.8% of samples exceeded the China standard. Over the past 3 years, the TVOC concentration decreased and then increased ( P < 0.05). The percentage of samples exceeding the China standard in the three rooms decreased in the following order: sitting room>study>bedroom. The characteristics of the TVOC source were a key factor influencing the TVOC concentration. In addition, the TVOC concentration was also ( P < 0.05) related to the temperature, humidity, time from the end of decoration to sampling (DR), and the amount of time windows and doors were closed before sampling (DC). The temperature and humidity were less important than the DR and DC. A model to relate the TVOC concentration to the five factors (temperature, humidity, source, DR, and DC) was established based on 288 samples ( R = 0.83). The model illustrated that the time for the TVOC concentration to meet the China standard was different for the various rooms, and when the other factors were fixed, the impact of DC ( t) on the TVOC concentration could be quantified as ((( t+1)/2)−1)×100%. [ABSTRACT FROM AUTHOR]

Abstract: A study was undertaken to determine the effect of variations in temperature, relative humidity, occupancy density and location (indoor/outdoor) on the concentrations of viable airborne bacterial and fungal spores at an air-conditioned and a non air-conditioned food stall in Singapore. Typically, bioaerosols consisted of 50.5% bacteria and 49.5% fungi in the indoor environment. In contrast, for the outdoor environment, bacteria on an average only accounted for 20.6% of culturable airborne microorganisms whereas fungal concentrations were 79.4%. Results on bioaerosol size distributions revealed that 67% of indoor bacteria and 68% of outdoor bacteria, 85% of indoor fungi and 68% of outdoor fungi were associated with fine mode particulates (<3.3 μm). Occupant density was the key factor that affected indoor airborne bacteria concentrations while concentrations of outdoor airborne bacteria depended strongly on ambient temperature. Indoor fungal concentration was positively correlated to relative humidity whereas outdoor fungal concentration was positively correlated to relative humidity and negatively correlated to temperature. The study also compared the biological air quality between a non air-conditioned food stall (Stall A) and an air-conditioned food stall (Stall B). The dining area of the former had lower bacterial concentrations as compared to the latter, while fungal spore’s concentrations showed a reverse trend. The dominant airborne bacteria genera were Staphylococcus, Pseudomonas, Alcaligens, and Corynebacterium whereas Penicillium, Aspergillus and Cladosporium were the most common fungal genera and groups in both food stalls. [Copyright &y& Elsevier]

Abstract: Research into dynamic moisture storage in hygroscopic building materials has renewed interest in the moisture buffering capacity of building materials and shown the potential for these materials to improve indoor humidity, thermal comfort and indoor air quality in buildings. This paper complements previous research by estimating the effect of hygroscopic materials on energy consumptions in buildings. The results show that it may be possible to reduce heating and cooling energy consumption by up to 5% and 30%, respectively, when applying hygroscopic materials with well-controlled HVAC systems. The paper also describes two different experimental facilities that can be used to measure accurately the moisture buffering capacity of hygroscopic building materials. These facilities provide different convective transfer coefficients between the hygroscopic material and ambient air, ranging from natural convection in small, sealed jars to fully developed laminar and turbulent forced convection. The paper presents a numerical model and property data for spruce plywood which will be used in a companion paper [O.F. Osanyintola, P. Talukdar, C.J. Simonson, Effect of initial conditions, boundary conditions and thickness on the moisture buffering capacity of spruce plywood, Energy and Buildings (2006), doi:10.1016/j.enbuild.2006.03.024.] to provide additional insight into the design of an experiment to measure the moisture buffering capacity of hygroscopic materials. [Copyright &y& Elsevier]

Studies of the indoor air quality of restaurants have rarely focused on ventilation system performance in relation to air pollutants and climatic factors. This study was conducted in eight restaurants to examine this issue by determining the ventilation flow rates and the levels of carbon dioxide (CO[sub 2]), ambient temperature, and relative humidity during at least one complete shift of serving a meal. The mean values of number of dining patrons, ventilation flow rates, and the levels of CO[sub 2], ambient temperature, and relative humidity were not significantly different in the nonsmoking dining rooms and the smoking dining rooms. The mean ventilation flow rates in individual restaurants ranged from 42-113 cubic feet per minute per person (cfm/person), overall exceeding the recommended lower limit of 30 cfm/person. The mean levels of CO[sub 2] in two restaurants (646 and 819 ppm) were below, and in the other six restaurants (ranging 1012-1820 ppm) were above the recommended upper limit of 1000 ppm. The levels of CO[sub 2] in each restaurant significantly correlated with the number of dining patrons and in four restaurants accumulated gradually over time. In the nonsmoking dining rooms, the levels of CO[sub 2] increased significantly as the ventilation flow rates decreased. The mean ambient temperature in restaurants (ranging from 22°C-24°C) were within the recommended range of 20°C-26°C. The mean relative humidity in six restaurants (ranging from 46%-59%) were within the recommended upper limit of 60 percent, and in two restaurants (62% and 71%) were slightly higher than this recommended limit. It was concluded that although the mean ventilation flow rates in all restaurants exceeded the recommended value, the design of the ventilation system or the distribution of air flow rate in some sections of restaurants were not appropriate to keep the levels of CO[sub 2] and relative humidity at some measurement locations below the recommended limits. [ABSTRACT FROM AUTHOR]

Data from a nationwide survey on the status of the Swedish residential building stock and indoor air quality was placed in the public domain by the National Board of Housing, Building and Planning of Sweden. The current research investigates the indoor humidity conditions in Swedish residential buildings, single-family houses and apartments, assessing the measurements from the extensive BETSI-survey against adjusted relative humidity levels based on existing norms and Standards. The aim of this study is to investigate associations and correlations between relative humidity levels and multiple building and system characteristics, occupancy patterns and behaviors and health symptoms-complaints. The analysis uses 13 categorical and 9 continuous variables-parameters of the examined dwellings. Analysis shows that low indoor relative humidity is a realistic issue in Swedish dwellings during the heating season. The issue is more prevalent in apartments than single-family houses. In addition, low indoor relative humidity seems to be more extensive in dwellings with higher indoor temperature, smaller volume, higher ventilation rate and frequent airing practices, lower number of occupants, constructed mainly after 1985, in city suburbs and in the northern parts of the country. The developed multinomial logistic regression model may predict very accurately the relative humidity level of the Swedish dwellings, during heating season. This analysis offers additional evidence to the scientific literature for possible correlation of low relative humidity with specific health symptoms, complaints and disturbances. • Low relative humidity is a realistic issue in Swedish dwellings, mainly apartments. • The issue is more extensive in dwellings with higher indoor temperatures. • Moisture supply values are suggested for this climate and dwellings. • Possible correlation of low relative humidity with specific health symptoms. • Method may be used widely also in epidemiological and health related campaigns. [ABSTRACT FROM AUTHOR]

In most urban environments, outdoor air pollutants affect indoor air quality. In 2019, Seoul, South Korea mandated filtered ventilation systems in newly constructed buildings to reduce PM 2.5 levels. This study aimed to evaluate PM 2.5 concentrations before and after the installation of a pre-filter and to analyze their behavior under different relative humidity conditions. The pre-filter system was installed in two selected houses (A and B) with the same ventilation system to evaluate indoor and outdoor PM 2.5 concentrations. To reduce indoor PM 2.5 concentrations through the ventilation system, a high-performance filtering system (G4 + F8 + H13) was installed. The ventilation system was better at maintaining indoor air quality than an air cleaner. Furthermore, the pre-filter was more effective in reducing PM 2.5 that was introduced from the outside rather than that generated indoors. The results revealed that after installation of the pre-filter system, the percentage of PM 2.5 concentration below 10 μg/m3 increased for house A and B, respectively. In addition, when the pre-filter was not installed, the average I/O ratio was 1.4 ± 0.09 and 2.3 ± 0.09 for house A and B, respectively. However, after the pre-filter was installed, the average I/O ratio for house A was 0.4 ± 0.58 and that for house B was 2.1 ± 0.05. After pre-filter installation, the percentage of I/O ratio (range of 0–1) increased with an increase in the relative humidity, that is from 72.1% to 95.1% for house A and from 8.5% to 24.7% for house B. Image 1 • Pre-filter installation prevents PM 2.5 inflow from outdoors to indoors. • After pre-filter installation, PM 2.5 below 10 μg/m3 increased. • Ventilation system was better at maintaining IAQ than an air cleaner. • I/O ratio <1 increased with an increase in relative humidity. • Increase in relative humidity is associated with a decrease in the I/O ratio. [ABSTRACT FROM AUTHOR]

• Thermal comfort and energy saving potential of DOAS-CF was studied. • Thermal comfort and IAQ acceptability were highest satisfaction at 27°C at 0.94 m/s. • Mean thermal sensation was highly correlated to the average SET* as a linear function. • Annual energy consumption of DOAS-CF was reduced by 25.8% as temperature rose 3°C. The performance of a Dedicated Outdoor Air System integrated with ceiling fans (DOAS-CF) to enhance thermal comfort, perceived air quality (PAQ) and energy-saving potential was examined. 26 subjects were exposed to the combinations of temperatures (24, 27 and 30°C) and air velocities in the range of 0.07 to 1.87 m/s at relative humidity (RH) of 60% for 3.5 h. The results showed that subjects felt thermally neutral and comfortable at 24°C with air velocity of 0.07 m/s, 27°C with air velocity of 0.94 m/s and 30°C with air velocity of 1.87 m/s. Thermal comfort (87%), thermal preference (72%), thermal acceptability (100%) and indoor air quality acceptability (98%) were highest at 27°C at 0.94 m/s. The mean thermal sensation was highly correlated to the average SET* as a linear function. An energy simulation tool (IES-VE) was used to simulate the energy consumption and quantify the energy savings of the DOAS-CF. Relative to a typical room design condition of 24°C with a conventional air-conditioning system, DOAS-CF achieved a 25.8% reduction in annual energy consumption when the room temperature was raised by 3°C but compensated by increased air movement. [ABSTRACT FROM AUTHOR]