TVOC Concentrations Research Articles

Indoor and outdoor air quality assessment in daycare centres in Ghent (Belgium) in view of outdoor sleeping in an urban environment

Within Flanders, there is an increasing trend to let children sleep outdoors while in daycare. However, within an urban environment, the densely spread emission sources might affect the air quality and possibly limit the areas where outdoor sleeping is favourable. Nevertheless, there is a lack of data regarding the atmospheric pollution levels in and around daycare centres (DCC). Therefore, the focus of this study is to chemically characterize the air quality indoors, outdoors, and in specifically designed cubicles for outdoor sleeping at 12 DCCs spread over the city of Ghent (Belgium). The measuring of a very broad range of different pollutants, provides unique data for indoor and outdoor air quality at daycare centres in Ghent. The use of axial tube (for volatile organic compounds, VOCs) and Radiello (for NO2, SO2, O3) passive samplers enables multi-component sampling, resulting in time-weighted average concentrations for one week. Forty-seven VOCs are identified and, for the majority (40), indoor to outdoor concentration (I/O) ratios higher than one are found. For the remaining seven compounds (e.g. benzene) outdoor concentrations are a factor 1.3–17.9 (median) higher than indoors. Median indoor TVOC concentrations are 152 μg/m3 and 142 μg/m3 for the September and January campaign, respectively. Outdoors, these median TVOC concentrations are much lower (24.5 μg/m3 and 30.6 μg/m3). For NO2, no noticeable differences are observed between average indoor and outdoor concentrations (indoors 12 ± 3 μg/m3 and 13 ± 2 μg/m3 for the September and January campaign, respectively, and outdoors 11 ± 3 μg/m3 and 14 ± 4 μg/m3). The highest (outdoor) measured concentration is 21 ± 1 μg/m3. SO2 concentrations are below 2.62 μg/m3 (LOQ). Average indoor O3 concentrations are 4 ± 3 μg/m3 and 2 ± 2 μg/m3 for the September and January campaign, respectively. Much higher values are measured outdoors (46 ± 3 μg/m3 and 40 ± 11 μg/m3), but the concentrations stayed well below legal standards.

Continuous monitoring of volatile organic compounds through sensorization. Automatic sampling during pollution/odour/nuisance episodic events

Volatile organic compounds (VOCs) are a highly diverse class of chemical contaminants and between 50 and 300 of them may be found in ambient air. In urbanized areas, VOCs are emitted from industrial activities, as well as from vehicle-related and combustion sources. VOCs outdoors can be detected in a broad range of concentrations, usually varying seasonally. The presence of VOCs at relatively high concentrations has been related to poor air quality, discomfort and odorous nuisances. Additionally, they can have negative health effects to the human organism. Hence, in locations where recurrent sporadic situations of high VOCs levels take place, episodic samples' evaluation is necessary instead of 24 h or longer sampling period's evaluations. The use of commercially available metal oxide semiconductor gas sensors for a continuous monitoring of VOCs concentrations in outdoor air is an interesting and innovative technology. Additionally, the use of these sensors for the activation of a VOCs sampler when episodic events of nuisance/odorous annoyance occur was successfully evaluated. The sensor activation is induced by higher VOCs concentrations from a wide number of VOC chemical families. Two sensor stations, developed at our laboratory and provided with sampling pumps, were located in the municipality of Santa Margarida i els Monjos (Catalunya, Spain) in January 2021. The stations started recording data continuously from two different types of VOCs sensors, temperature, relative humidity and pressure in 1.5-min periods. Automatic VOCs sampling was conducted, using multi-sorbent bed tubes, during the months of June–July when the sensors electronic values exceeded a set point value. Samples were analysed through TD-GC/MS. TVOC concentrations in episode samples ranged between 78-669 and 12–159 μg m−3 in Site 1 and Site 2, respectively. Although TVOC concentrations were not high in all cases, relevant concentrations of chloroform were observed, especially in Site 1, with concentrations ranging from 19 to 159 μg m−3.

Impact of fine particulate matter and toxic gases on the health of school children in Dhaka, Bangladesh

Background. Air pollution exposure has a detrimental effect on children who spend more than 17% of their weekdays inside a school building. The purpose of this study is to look into the effects of particulate matter (PM) and toxic gases on health of the school children. Between April and November 2018, samples were collected in real time from ten different schools (both indoor and outdoor) over four hours on two consecutive days at each school. During the first two hours, when students were present in the classroom, measurements were conducted inside the classroom. After that the measurements were conducted outside the classroom but within the school premises - when students were playing on the playground or eating breakfast outside of classroom. Method. To evaluate the impact of air pollution, 250 students (on average 20 students from each school) aged from 9 to 12 were selected from ten schools. Automatic monitors (AEROCET 531S, USA) were employed to measure PM1.0, PM2.5, and PM10 concentrations. NO2, TVOC, and CO2 concentrations were measured using an AEROQUAL (500S, New Zealand), and the respiratory rate is measured by BSMI Peak Flow Meter (Made: BSMI, Origin: China). Monitors were placed at about 2.0 meters above the floor at breathing height and no student wore the sensors. The ANOVA test was conducted to see the statistical significance between air quality parameters and peak flow meter readings. Results. The mean ± standard deviation of PM1.0, PM2.5, and PM10 concentrations were 19.1 ± 3.6, 34.2 ± 10.1, and 131.3 ± 58.6 μgm−3, respectively. PM2.5 and PM10 concentrations exceeded WHO standards (15 and 45 μgm−3 of 24 h) by 2.3 and 2.9 times. The highest concentrations of toxic gases were found on school campuses where vehicle densities (measured manually) were high. The mean Hazard Quotient (HQ) for PM10 (2.5 ± 2.2 indoor; 3.6 ± 2.6 outdoor) and PM2.5 (1.8 ± 0.8 indoor; 1.9 ± 1.0 outdoor) among all participating students was >1 indicating an unacceptable risk for human health. Lung function associated with the PEF value has a negative correlation with PM1.0 and PM2.5 concentrations in most cases. Conclusions. The findings of this study are useful in gaining a general understanding of the school environment in Dhaka. It aimed to understand how children were personally exposed in school and to develop effective control strategies to mitigate negative effects.

A Pilot Study on the Combined Multi-domain Impact of Indoor Air Quality and Noise on Office Productivity

As people spend 90% of their time indoors, it was necessary to improve indoor environmental quality to enhance human productivity. Indoor environmental quality consists of indoor air quality (IAQ), thermal, visual, and acoustic comfort. However, only a few studies have investigated the combined effects of IAQ and noise. During and after the COVID-19 pandemic, portable air cleaner is often used in buildings to reduce the concentration of particles in the air, but it also generates noise. The objective of this study is to determine the effects of a portable air cleaner on IAQ and noise level, and more importantly the resulting combined effects on office productivity. For this purpose, we conducted human subject tests in an office and each test lasted for 1.5h. For each case, the air temperature, relative humidity, and supply airflow rate were kept constant while the air cleaner was switched between on and off for various noise levels and IAQ. We recruited 7 participants and collected data on the concentration of CO2, particles, and TVOC every 5 minutes. We used wristbands to measure heart rate and skin electrodermal activity. And we used headbands to measure electroencephalogram (EEG) and facial activity. The questionnaire survey was used to learn the occupants’ responses to the indoor environment. To learn their productivity, occupants also did math addition tasks and typing tasks. We found that when using the portable air cleaner, the noise level raised from 55dB to around 70dB. The particle and TVOC concentrations were reduced by 90% and 20%, respectively. The questionnaire survey showed that the occupants felt unsatisfied due to noise. And the noise dissatisfaction exceeded the improved IAQ. By analyzing the EEG and the number of jaw clenches, the occupants felt more nervous and concentrated when the air cleaner was on. We confirmed the impact of noise and the combined impact of IAQ and noise on office productivity.

Air quality investigation and research for various types of student-oriented indoor environments on a university campus

This study investigated suspended particles (PM2.5 and PM10), formaldehyde, TVOC, ozone, carbon dioxide, and carbon monoxide in seven student-oriented indoor environments, which are inclusive of the library study room (A), computer classroom (B), teacher and student compound office (C), classroom-1 (D), classroom-2 (E), student cafeteria (F), and underground motorcycle parking lot (G) on a university campus. We monitored each indoor environment during the open hours for at least three weekdays. The averaged concentrations of CO2 in environments A, B, C, and D all exceeded the standard (1000 ppm) with values of 2,628±375, 1,908±613, 1,752±495, and 1,076±280 ppm. The corresponding minimum and maximum CO2 concentrations were 1,101 and 3,314, 836 and 3,272, 672 and 2,667, and 752 and 2,040 ppm, respectively. Sites A, B, C, D, F, and G are the environments where the concentrations of TVOC exceeded the standard (560 ppb) with the averaged values of 829±21, 920±192, 582±8, 607±15, 640±102 and 815±205 ppb, respectively. Both concentrations of PM2.5 and PM10 in site F exceeded the standards (i.e., 35 μg/m3 and 75 μg/m3) with averaged values of 39±13 μg/m3 and 103±51 μg/m3, respectively. Three target compounds, CO, O3, and HCHO, were below their respective standards.

Analysis of Impacts of Window Opening Behavior on Indoor Air Pollutants in Residential Dorms through Deep Neural Network

People spend more than 90% of their time in buildings. The highly stochastic behavior of occupants can alter the pollutants concentration in an indoor space. Many studies have reiterated that window opening is one of the best methods to reduce indoor pollutant concentration. In this study, we analyzed the influence of window opening behavior on indoor pollution parameters (CO2 and TVOC) in 16 student dorms in Syracuse, NY. The duration of the study encompasses all major seasons of a whole year. We found that the window opening behavior of the living room is triggered by the increased concentration of indoor pollutants. The impact of the window opening on the dilution of the concentration of the indoor pollutants is analyzed using the air exchange rates. We found that the average infiltration air exchange rate is 0.32 h-1 and the average air exchange rate during the window opening is 2.20 h-1. The exchange rates are different in different homes; infiltration ACH range from 0.31 - 0.83 h-1, and window opening ACH range from 0.46 - 3.86 h-1. The mean indoor CO2 concentration for all homes ranges between 458 - 715 ppm, and the mean TVOC concentration is 268 - 1786 ppb. The average error in the loss rate calculated from the mass-balance model and the blower door test is 2.51%. We made a Deep Neural Network model predict the concentration of CO2 in the indoor space based on the window's state. The DNN model has an RMSE of 7 ppm and a MAPE of 6.66%. The DNN predicts that the exposure during decay events at the window opening is 80.31% lower than during closed state decay.

The Effect of Students, Computers, and Air Purifiers on Classroom Air Quality

Indoor air pollutant sources are crucial in assessing IAQ, especially when outdoor air pollutant concentrations are low. In the present study, PM mass concentrations in a range of five sizes; CO, CO2, O3, NO, NO2, and TVOC concentrations; along with temperature and relative humidity were monitored in three indoor locations of a university. The monitoring took place in a building dedicated to teaching undergraduates. The first two locations, a professor’s office and a computer centre (laboratory), were not refurbished. The classroom under study is refurbished and now is airtight, as are all of the classrooms in this building. Air purifiers were installed in all of the classrooms to prevent the transmission of infectious pollutants. In all monitored locations, people were the main indoor source of PM, CO2, and TVOC. The operation of twelve computers in the small laboratory did not contribute to the air pollution, at least for the examined pollutants. The air purifier decreased the PM concentrations, but not the gaseous air pollutants.

One-year spatiotemporal variations of air pollutants in a major chemical-industry park in the Yangtze River Delta, China by 30 miniature air quality monitoring stations

Fine chemical industrial park (FCIP) is a major source of atmospheric pollutants in China. A long-term high spatial resolution monitoring campaign on air pollutants had been firstly conducted in a major FCIP in Yangtze River Delta (YRD) from December 2019 to November 2020. The grid-based monitoring platform consisting of 30 miniature air quality monitoring stations (AQMSs) provided comprehensive coverage of a FCIP, and long-term monitoring studies solved the problem of lack of clarity about pollution sources in industrial parks. Overall, NO2 pollution was particularly high in the pharmaceutical industry, while TVOCs and O3 pollution were most serious in the textile dyeing industry, with PM pollution much higher in the metal smelting industry than in other industries, and in the leather industry, O3 pollution was relatively severe. The spatial and temporal variations of air pollutants showed that higher PM, CO and NO2 concentrations were revealed in winter while lower in summer due to better meteorological diffusion conditions. TVOCs concentrations were higher with an average of 1954 ppb in summer possibly due to their increased volatilization from their sources at higher ambient temperatures. O3 concentrations were at their peaks in spring (88.8 μg m−3) and early fall (78.5 μg m−3). The daily trends of O3 precursors (TVOCs and NO2) were clearly negatively correlated with O3, and they showed bimodal peaks due to anthropogenic activities, plant emissions, lowering of the mixed boundary layer, etc. The O3 formed in FCIP was judged to be NO2-limited during the monitoring period based on the ratios of NO2 to TVOCs. Therefore, the effective strategy to reduce O3 formation in FCIP is to decrease the ambient NO2 concentration. Based on Pearson correlation coefficients, it appeared that WS promoted O3 formation through long-term transport and that high air temperatures also contributed to O3 formation in the environment. It was also stated in the study that the closer the residential area is to the industrial sources, the more significant the correlation. Thus, the results of this study will also be helpful for policymakers to design pollutant control strategies for different industries to mitigate the impact of pollutants on human health.

Air pollution characteristics and human health risk assessment of underground parking garages in Xi’an, China

Due to the rapid increase of population density and automobile vehicle numbers in mega-cities, large underground garages have become universal supporting facilities to meet the demand for parking spaces in the recently-built commercial complexes and high-rise residential communities. Natural ventilation was insufficient to discharge vehicle-induced pollutants out of the enclosed underground spaces, which could pose a potential threat to people’s health. This study aims to determine the spatial and temporal distribution characteristics of pollutants concentration and the health risk of underground parking garages (UPGs)’ staff and users. Field measurements were conducted on the air pollutants concentrations and the users’ exposure characteristics in 11 commercial UPGs and three high-rise residential UPGs with natural ventilation in Xi’an. The pollutants concentrations were higher in the afternoon and morning of commercial and high-rise residential UPGs. In general, the particulate matters (PM2.5 and PM10), HCHO, TVOC and BTEX (benzene, toluene, ethylbenzene and xylenes) concentrations in commercial and residential UPGs were 0.069/0.067 mg/m³, 0.12/0.097 mg/m³, 0.014/0.017 mg/m³, 1.8/1.8 mg/m³, 0.056/0.10 mg/m³, 0.19/0.29 mg/m³ and 0.41/0.49 mg/m³, respectively. TVOC and BTEX concentrations in UPGs significantly correlated with traffic volume ( p < 0.01). In different groups, the entropy values of carcinogenic and non-carcinogenic risks were: staffs > children travelling with adults > adults. In particular, occupational long-term (employee) exposure could lead to both carcinogenic and non-carcinogenic risks.

Residential VOCs concentration levels in Nsukka, Nigeria

The concentrations of 26 VOCs were measured in ten rural and ten urban households for two 7-day sampling campaigns in the Nsukka area, Southeast Nigeria, between 2017 and 2019. Samples were passively collected in the kitchen, living room, and outdoor using Tenax TA axial sorbent tubes. Analysis was done by thermal desorption gas chromatography coupled with mass spectrometry using ethylbenzene-d10 as an internal standard. The wet season kitchen and outdoor TVOCs are 265 and 45 μg/m3 in urban, and 199 and 21 μg/m3 in rural households. The dry season median TVOCs concentrations in the kitchens, living rooms, and outdoors are 254, 115, and 71 μg/m3 in urban and 324, 145, and 41 μg/m3 in rural areas, indicating a rank order of kitchen > living room > outdoor. This indicates spatial and seasonal variability of the VOCs concentration among the locations in the homes and between urban and rural areas. However, the difference between the urban and rural TVOCs levels is only significant (p < 0.05) for the outdoor levels.The TVOCs indoor to outdoor concentration ratios for the kitchen during the dry season are 1.3–18, implying indoor sources. The median (range) benzene concentrations in the kitchens are 80 μg/m3 (10–306 μg/m3), 47 μg/m3 (18–90 μg/m3), 26 μg/m3 (4–122 μg/m3), and 15 μg/m3 (8–104 μg/m3) for kitchens using firewood, charcoal, kerosene, and LPG which indicates that exposure to benzene could be five times more in firewood kitchens than in LPG ones. Furthermore, the estimated lifetime cancer risk and hazard quotient from the present study exceed the respective thresholds of 6.00E-06 and 1.0, indicating that people are at risk in the studied homes and underscores the urgency for effective air quality management in the area.

Characteristics, Sources, and SOAP of VOCs During Winter in Jiyuan

Haze pollution events often occur in the heavy industry city of Jiyuan. Volatile organic compounds (VOCs) are the precursors of secondary organic aerosol (SOA), which accounts for 15%-20% of particulate matter (PM2.5). Here, PM2.5, O3, VOCs, and trace gases were monitored by using online instruments in Jiyuan from December 1st to 31st. The characteristics, sources, and secondary organic aerosol potential (SOAP) of VOCs were analyzed. The mean concentrations of TVOC were (54.3±27.5)×10-9. Alkanes, halocarbons, and alkynes were the predominant VOCs. The positive matrix factorization model was used to identify and apportion VOCs sources. Eight major sources of VOCs were identified, which included liquefied petroleum gas (LPG) or natural gas (NG), the polyvinyl chloride (PVC) industry, vehicular exhaust, the coking industry, solvent usage, industry, technological process, and fuel evaporation. The SOAP of aromatics was the largest. Among them, BTEXs were the dominant contributors to SOAP.

Integrated on-site collection and off-site analysis of airborne molecular contamination in cleanrooms for integrated circuit manufacturing processes

Both long-term on-site collection and off-site analysis methods were conducted to investigate airborne molecular contaminants (AMCs) in a semiconductor wafer cleanroom. The removal efficiency of SO2 and NO2 for chemical filters on a make-up air unit (MAU) in the cleanroom is approximately 50%, though this value does not meet the removal efficiency mentioned in the GB 36306 standard. The removal efficiencies of SO2, H2S, NO, NO2, NH3, and TVOC were approximately 76.5%, 50.9%, 83.5%, 99.3%, 94.8%, and 97.1% after the fan filter unit (FFU) was equipped with a chemical filter. AMCs mainly include benzene, toluene, ethylbenzene, xylene (BTEX), alkanes and alkenes, though BTEX accounts for 77% of the total. VOC concentrations in cleanrooms fitted with FFU chemical filters and where the process equipment was not in operation were found to be lower than those at domestic residences and slightly higher than those found in commercial aircraft cabin air. The daily average TVOC concentrations were negatively correlated with temperature (R2 = 0.46, p < 0.01) and positively correlated with humidity (R2 = 0.26, p < 0.01). The daily average NH3 concentrations were negatively correlated with T (R2 = 0.19, p < 0.05) and positively correlated with RH (R2 = 0.18, p < 0.01). Dibutyl phthalate (DBP) and dioctyl phthalate/diethylhexyl phthalate (DOP/DEHP) were detected in the new sealing joint strips in the HEPA filters. Phthalates and organophosphates were not detected in the new filter papers.

Investigation of indoor air quality in university libraries in terms of gaseous and particulate pollutants in Bartin, Turkey.

Indoor air quality (IAQ) was investigated in two libraries of Bartin University. Particle matter, TVOC, and CH2O were measured simultaneously in different rooms of the libraries. Measurements were made by PCE-RCM 11 measuring device. They were conducted monthly between September 2019 and October 2020 for 2 weeks for each library. TVOC mean concentration was higher than the limit value reported by Seifert et al. (1999). PM2.5 and PM10 concentrations were higher in winter unlike TVOC and CH2O concentrations. The indoor seconder blowing dust was detected to be the most important source of particulate matter in the indoor environment. On the other hand, it was thought that the pollutants in the gas phase were affected by indoor and outdoor air temperature, indoor/outdoor air exchange rate, and indoor/outdoor pollutant sources. The parameters changed during the day and in different rooms of the libraries. Pollutants did not pose any hazard on human health, since the calculated HQ and HI ≤ 1 for both exposure groups. The indoor air of the libraries was detected to be slightly polluted and bad according to the IAQI and IEI, respectively. On the other hand, the indoor air quality of the libraries was good in terms of all parameters according to the IAQC.Supplementary informationThe online version contains supplementary material available at 10.1007/s10661-022-09818-8.

Data fusion of mobile and environmental sensing devices to understand the effect of the indoor environment on measured and self-reported sleep quality

The Indoor Air Quality (IAQ) of the bedroom environment has recently garnered attention since air pollution can affect sleep. Previous studies investigated IAQ and sleep quality in controlled environments which impacts both self-reported and measured sleep quality. Studies within a participant’s home environment are ecologically valid and reduce participant bias. Here, we study 20 participants over 77 days in Austin, TX. We monitored five components of IAQ using the BEVO Beacon, a calibrated purpose-built environmental monitor, and measured participant sleep quality through wearable activity trackers and 4-question surveys sent four times a week. We found significant decreases in sleep quality during nights with elevated CO, CO2, and temperature. Elevated CO was associated with a mean increase in 0.9 self-reported awakenings and decreases in device-measured sleep time of 21.6 min and sleep efficiency of 0.6%. Increased CO2 and temperature were associated with decreases in device-measured sleep time of 17.5 and 15.2 min, respectively. Elevated PM2.5 and TVOCs concentrations were associated with overall improvements in sleep quality. Participants reported a mean of 4.4 fewer awakenings and had a 1.1% increased in measured sleep efficiency for nights with elevated PM2.5. Elevated TVOCs were associated with an increase in sleep time of 14.5 min. These findings indicate a need to study the relationship between these aggregate IAQ measures and sleep quality more closely. Our results also indicate that pollutants can independently affect sleep quality regardless of the CO2 measurements. Compared to literature, our study is the longest and includes the most IAQ parameters.

Field investigation of pollutant characteristics and targeted ventilation control strategies in high-ceiling aircraft spraying workshop

To achieve efficient ventilation and purification in the high-ceiling painting workshop is faced with the contradiction between effect and energy consumption. Understanding the characteristics of gaseous pollutants is of paramount importance for ventilation and purification system design. The composition and concentration of volatile organic compounds (VOCs) emitted from aircraft painting workshop were sampled by Tenax-TA tubes and analyzed with gas chromatography-mass spectrometry (GC-MS). Approximately 50 types of VOCs (detection rate>50%) were detected in the aircraft spraying workshop, with percentages of 36.3% for esters, 31.9% for aldehyde ketones, 28.5% for biphenylenes, 1.9% for alcohols and 1.4% for alkanes. The TVOC concentrations in the workshop were 48.6 mg/m3 and 132.4 mg/m3, during the varnish painting and the finish painting processes, respectively, and these are several times higher than those observed in other industries (automobile painting and wooden furniture painting). The field test data of spraying workshops from 197 spraying factories in five industry sectors were collected from field measurement and existing literature. Some VOCs components are the general pollutants in the painting workshops, such as Acetic acid, butyl ester, Toluene, and 2-Butanone. A novel ventilation model using multiple target purification units is proposed to eliminate the pollutants in an aircraft spraying workshop. Compared with the original trench exhaust system, the air volume of the proposed targeted ventilation system is reduced by 75%, and the energy consumption is reduced by 45,000 kW·h per aircraft.

Automatic detection method of atmospheric pollutant concentration based on multi-sensor data fusion

Aiming at the problem that the traditional air pollutant concentration detection method cannot accurately detect the concentration of multiple pollutants, an automatic detection method of air pollutant concentration based on multi-sensor data fusion is proposed. A multi-sensor environment detection system is constructed by the temperature and humidity sensor DHT22, the NO2 sensor ZE08-CH2O and the dust sensor ZPH01, and the multi-sensor data fusion is realised by the Kalman filter algorithm. The improved BP network is used to classify pollution source data, and the detection data of the same pollution source is back calculated by adaptive simulated annealing algorithm to realise the automatic detection of the concentration of similar air pollutants. The experimental results show that the detection errors of this method for the concentration of atmospheric pollutants NO2, TVOC and PM2.5 inhalable particulate matter are 0.03 μg·m-3, 0.02 μg·m-3, 0.03 μg·m-3 respectively, which proves the effectiveness of this method.

Associations between indoor VOCs and childhood asthma in Shanghai, China: an analysis stratified by frequency of window opening during night

Few studies pay attention to the possible associations between indoor VOCs and childhood asthma in Shanghai considering the effect of household ventilation. From March 2013 to December 2014, we collected air samples from 358 children's bedrooms in Shanghai, China. Information on childhood asthma, environmental exposures, and lifestyle behaviors was collected. Two-sample of Mann-Whitney U test, bivariate logistic regressions, and multiple logistic regression were used to obtain the association between VOCs and childhood asthma. Association analysis stratified by frequency of window opening during night was conducted to explore its possible effect on the target association. High concentrations of toluene and dodecane were significantly associated with childhood wheeze, and a high concentration of toluene was significantly associated with diagnosed asthma. In the bedrooms with low frequency of window opening during night, high concentrations of toluene, dodecane, and TVOC were significantly associated with childhood wheeze, and a high concentration of toluene was significantly associated with diagnosed asthma. Our results indicate that exposure to VOCs may be a risk factor for childhood asthma, especially in the bedrooms with poor ventilation during night. Family avoidance behaviors of household ventilation should be considered in the study of associations of household VOCs with childhood asthmatic symptoms.

The Determination of Indoor Air Quality and Thermal Comfort with Different Space and Ventilation in the Teracce and Bungalow Houses

This study observed the influence of different ventilation, indoor and outdoor activities (i.e., cooking, praying, sweeping, gathering, and exhaust from motorcycle) between a bungalow house (i.e., stack and cross ventilation applications) and a terrace house (i.e., one-sided ventilation application). We appraised the indoor air quality (IAQ) and thermal comfort. We monitored the indoor air contaminants (i.e., TVOC, CO, CH2O, PM10, O3, and CO2) and specific physical parameters (i.e., T, RH, and AS) for four days in the morning (i.e., 6.00 a.m. – 9.00 a.m.), morning-evening (i.e., 11.00 a.m. – 2.00 p.m.), and evening-night (i.e., 5.00 p.m. – 8.00 p.m.) sessions. The results found that cooking activities are the major activities that contributed to the increase of the TVOC, CO, PM10, O3, and CO2 concentrations in the bungalow and terrace houses. However, IAQ exceeded the Industry Code of Practice on IAQ (ICOP) limit in the terrace house. The bungalow house applies stack and cross ventilation, double area, and a long pathway of indoor air contaminants movements. Besides that, the results indicated that cooking activities worsen the ventilation system because CO2 exceeded the ICOP limit on Day 2 at 74.1 % (evening-night session) and Day 3 at 13.2 % (morning session), 11% (morning-evening session), and 50.1 % (evening-night session). Moreover, the combination of mechanical (i.e., opened all fans) and natural ventilation (i.e., opened all doors, windows, and fans) is the best application in the house without a cooking ventilator with lower indoor air movement. Furthermore, the temperatures exceeding the ICOP limit of 23-26 °C for both bungalow and terrace houses could be lower indoor air movement, which is less than the ICOP limit of 0.15-0.5 m/s and high outdoor air temperature. Therefore, it is prudent to have an efficient ventilation system for acceptable indoor air quality and thermal comfort in the family house.

Identification of key volatile organic compounds in aircraft cabins and associated inhalation health risks

The identification of key VOCs during flights is important in creating a satisfactory aircraft cabin environment. Two VOC databases for the building indoor environment (from 251 occupied residences) and the aircraft cabin environment (from 56 commercial flights) were compared, to determine the common compounds (detection rate (DR) > 70%) in the two environments and the characteristic VOCs (only those with high DR during flights) in aircraft cabins. Possible VOC emission sources in flights were also discussed. As TVOC is usually viewed as a general indicator of air quality, the prediction of TVOC concentration was carried out using BP neural network algorithm, and the average error between the predicted and measured values was 55.35 μg/m3 (R2 = 0.80). Meanwhile, the VOCs’ inhalation cancer/non-cancer risks to crew members and passengers were calculated on the basis of detection rates, exposure concentrations, and health risk assessments. Six compounds (i.e., formaldehyde, benzene, tetrachloroethylene, trichloromethane, 1,2-dichloroethane, and naphthalene) were proposed as the key VOCs in the existing aircraft cabin environment, presenting a risk to crew members that is higher than the US EPA proposed acceptable level (evaluated mean value > 1E-06). The estimated lifetime excess cancer/non-cancer risks for passengers were all below the assessment criteria. Based on a summary of various VOC limits in five built environments, hierarchical design of VOC concentration limits is recommended for the aircraft environment.

Parametrized design for the integration of range hood and air cleaner in the kitchen

This study proposed a novel integrated design combing an air cleaner with the conventional exhaust hood for the improvement of indoor air quality in the residential kitchen. Airflow interaction between the exhaust confluence of the range hood and the strong momentum induced by air cleaner was investigated for this kind of compact configuration. The potential of energy saving by using the air cleaner was discussed. Firstly, numerical simulation was employed to obtain well-organized recirculation purification parameters under different air outlet widths and angles and experiments were conducted to verify the control effect of pollutant concentration in the kitchen space with the good design. Results show that the oblique upward air supply of the air cleaner was found significantly better to clean the kitchen space than horizontal and oblique downward supply. The relative purification effect of the integrated air cleaner is less affected by the exhaust flowrate of the hood. The PM2.5 concentration reduction rate by the air cleaner at the breathing zone is near 60%, while the TVOC concentration reduction approximately 30%. Secondly, concentration decay rate at post-cooking period with/without the integrated air cleaner was measured and compared. It was found that the concentration decay rate achieved by the integrated air cleaner with 100 m3/h and oblique upward air supply is close to the decay rate of exhaust hood with 200 m3/h. It means that the integrated design proposed in this study is effective in reducing human exposure to cooking-related pollutants and has a significant energy-saving potential.