Characterization of indoor air quality in primary schools in Antwerp, Belgium

The indoor air quality of 27 primary schools located in the city centre and suburbs of Antwerp, Belgium, was assessed. The primary aim was to obtain correlations between the various pollutant levels. Indoor:outdoor ratios and the building and classroom characteristics of each school were investigated. This paper presents results on indoor and local outdoor PM2.5 mass concentrations, its elemental composition in terms of K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Pb, Al, Si, S, and Cl, and its black smoke content. In addition, indoor and local outdoor levels of the gases NO2, SO2, O3, and BTEX (benzene, toluene, ethyl benzene, and xylene isomers) were determined. Black smoke, NO2, SO2 and O3, occurred at indoor:outdoor ratios below unity, indicating their significant outdoor sources. No linear correlation was established between indoor and outdoor levels for PM2.5 mass concentrations and BTEX; their indoor:outdoor ratios exceeded unity except for benzene. Classroom PM2.5 occurred with a different elemental composition than local outdoor PM2.5. The re-suspension of dust because of room occupation is probably the main contributor for the I/O ratios higher than 1 reported for elements typically constituting dust particles. Finally, increased benzene concentrations were reported for classrooms located at the lower levels. PRACTICAL IMPLICATIONS: The elevated indoor PM2.5, and BTEX concentrations in primary school classrooms, exceeding the ambient concentrations, raise concerns about possible adverse health effects on susceptible children. This is aggravated by the presence of carpets and in the case of classrooms at lower levels. Analysis of PM2.5's elemental composition indicated a considerable contribution of soil dust to indoor PM2.5 mass. In order to set adequate threshold values and guidelines, detailed information on the health impact of specific PM2.5 composites is needed. The results suggest that local outdoor air concentrations measurements do not provide an accurate estimation of children's personal exposures to the identified air pollutants inside classrooms.     

Indoor air quality in Portuguese schools: levels and sources of pollutants

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM_2.5, PM₁₀, bacteria and fungi, carbon dioxide (CO₂), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO₂ and occupancy data. Concentrations of CO₂ exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 μg/m³) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO₂ levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools.     

Assessment of ventilation and indoor air pollutants in nursery and elementary schools in France

The aim of this study was to characterize the relationship between Indoor Air Quality (IAQ) and ventilation in French classrooms. Various parameters were measured over one school week, including volatile organic compounds, aldehydes, particulate matter (PM_2.5 mass concentration and number concentration), carbon dioxide (CO₂), air temperature, and relative humidity in 51 classrooms at 17 schools. The ventilation was characterized by several indicators, such as the air exchange rate, ventilation rate (VR), and air stuffiness index (ICONE), that are linked to indoor CO₂ concentration. The influences of the season (heating or non‐heating), type of school (nursery or elementary), and ventilation on the IAQ were studied. Based on the minimum value of 4.2 l/s per person required by the French legislation for mechanically ventilated classrooms, 91% of the classrooms had insufficient ventilation. The VR was significantly higher in mechanically ventilated classrooms compared with naturally ventilated rooms. The correlations between IAQ and ventilation vary according to the location of the primary source of each pollutant (outdoor vs. indoor), and for an indoor source, whether it is associated with occupant activity or continuous emission.     

Winter indoor air quality,thermal comfort and acoustic performance of newly built secondary schools in England

Previous studies have found that classrooms are often inadequately ventilated, with the resultant increased risk of negative impacts on the pupils. This paper describes a series of field measurements that investigated the indoor air quality, thermal comfort and acoustic performance of nine recently built secondary schools in England. The most significant conclusion is that the complex interaction between ventilation, thermal comfort and acoustics presents considerable challenges for designers. The study showed that while the acoustic standards are demanding it was possible to achieve natural ventilation designs that met the criteria for indoor ambient noise levels when external noise levels were not excessive. Most classrooms in the sample met the requirement of limiting the daily average CO₂ concentration to below 1500 ppm but just a few met the need to readily provide 8 l/s per person of fresh air under the easy control of the occupants. It would seem that the basic requirement of 1500 ppm of CO₂ is achieved as a consequence of the window areas being just sufficient to provide the minimum of 3 l/s per person at low and intermittent occupancy. Thermal comfort in the monitored classrooms was mostly acceptable but temperatures tended to be much higher in practice than the design assumed.     

Ventilation strategies and indoor particulate matter in a classroom

Particle mass and number concentrations were measured in a mechanically ventilated classroom as part of a study of ventilation strategies for energy conservation. The ventilation system was operated either continuously, intermittently, or shut down during nights while it was on during workdays. It appears that the nighttime ventilation scheme is not important for indoor particle concentrations the following day if fans are operated to give five air exchanges in advance of the workday. The highest concentrations of PM₁₀ were found during and after workdays and were due to human activity in the classroom. The average workday PM₁₀ concentration was 14 μg/m³, well below the WHO guideline values. The number concentration of particles with diameter <0.750 μm was typically between 0.5 × 10³ and 3.5 × 10³ particle/cm³. These concentrations were largely independent of the occupants. Transient formation of small particles was observed when ventilation was shut down. Then remaining ozone reacted with terpenes emitted by indoor sources and gave up to 8 × 10³ particle/cm³ before formation stopped due to lack of ozone. The intermittent ventilation regime was found least favorable for the indoor air quality in the classroom.     

Status of the indoor air chemical pollution in Japanese houses based on the nationwide field survey from 2000 to 2005

This paper describes the present state and the changes in indoor air pollution levels by Volatile Organic Compounds (VOCs) in houses in Japan, as revealed through measurements of indoor VOC concentrations and investigations on the actual conditions in the residential environment by means of a questionnaire survey covering a total of more than 10,000 newly built houses over six years (from 2000 to 2005). The VOCs initially measured were formaldehyde, toluene, xylene, and ethylbenzene, followed by the subsequent inclusion of styrene and acetaldehyde.     

Unexpected increase in indoor pollutants after the introduction of a smoke‐free policy in a correctional center

Correctional centers (prisons) are one of the few non‐residential indoor environments where smoking is still permitted. However, few studies have investigated indoor air quality (IAQ) in these locations. We quantified the level of inmate and staff exposure to secondhand smoke, including particle number (PN) count, and we assessed the impact of the smoking ban on IAQ. We performed measurements of indoor and outdoor PM_2.5 and PN concentrations, personal PN exposure levels, volatile organic compounds (VOCs), and nicotine both before and after a complete indoor smoking ban in an Australian maximum security prison. Results show that the indoor 24‐h average PM_2.5 concentrations ranged from 6 (±1) μg/m³ to 17 (±3) μg/m³ pre‐ban. The post‐ban levels ranged from 7 (±2) μg/m³ to 71 (±43) μg/m³. While PM_2.5 concentrations decreased in one unit post‐ban, they increased in the other two units. Similar post‐ban increases were also observed in levels of PN and VOCs. We describe an unexpected increase of indoor pollutants following a total indoor smoking ban in a prison that was reflected across multiple pollutants that are markers of smoking. We hypothesise that clandestine post‐ban smoking among inmates may have been the predominant cause.     

Quantification of the impact of cooking processes on indoor concentrations of volatile organic species and primary and secondary organic aerosols

Cooking is recognized as an important source of particulate pollution in indoor and outdoor environments. We conducted more than 100 individual experiments to characterize the particulate and non‐methane organic gas emissions from various cooking processes, their reaction rates, and their secondary organic aerosol yields. We used this emission data to develop a box model, for simulating the cooking emission concentrations in a typical European home and the indoor gas‐phase reactions leading to secondary organic aerosol production. Our results suggest that about half of the indoor primary organic aerosol emission rates can be explained by cooking. Emission rates of larger and unsaturated aldehydes likely are dominated by cooking while the emission rates of terpenes are negligible. We found that cooking dominates the particulate and gas‐phase air pollution in non‐smoking European households exceeding 1000 μg m^?3. While frying processes are the main driver of aldehyde emissions, terpenes are mostly emitted due to the use of condiments. The secondary aerosol production is negligible with around 2 μg m^?3. Our results further show that ambient cooking organic aerosol concentrations can only be explained by super‐polluters like restaurants. The model offers a comprehensive framework for identifying the main parameters controlling indoor gas‐ and particle‐phase concentrations.     

Toxicity and elemental composition of particulate matter from outdoor and indoor air of elementary schools in Munich, Germany

Outdoor particulate matter (PM(10)) is associated with detrimental health effects. However, individual PM(10) exposure occurs mostly indoors. We therefore compared the toxic effects of classroom, outdoor, and residential PM(10). Indoor and outdoor PM(10) was collected from six schools in Munich during teaching hours and in six homes. Particles were analyzed by scanning electron microscopy and X-ray spectroscopy (EDX). Toxicity was evaluated in human primary keratinocytes, lung epithelial cells and after metabolic activation by several human cytochromes P450. We found that PM(10) concentrations during teaching hours were 5.6-times higher than outdoors (117 ± 48 μg/m(3) vs. 21 ± 15 μg/m(3), P < 0.001). Compared to outdoors, indoor PM contained more silicate (36% of particle number), organic (29%, probably originating from human skin), and Ca-carbonate particles (12%, probably originating from paper). Outdoor PM contained more Ca-sulfate particles (38%). Indoor PM at 6 μg/cm(2) (10 μg/ml) caused toxicity in keratinocytes and in cells expressing CYP2B6 and CYP3A4. Toxicity by CYP2B6 was abolished with the reactive oxygen species scavenger N-acetylcysteine. We concluded that outdoor PM(10) and indoor PM(10) from homes were devoid of toxicity. Indoor PM(10) was elevated, chemically different and toxicologically more active than outdoor PM(10). Whether the effects translate into a significant health risk needs to be determined. Until then, we suggest better ventilation as a sensible option. PRACTICAL IMPLICATIONS: Indoor air PM(10) on an equal weight base is toxicologically more active than outdoor PM(10). In addition, indoor PM(10) concentrations are about six times higher than outdoor air. Thus, ventilation of classrooms with outdoor air will improve air quality and is likely to provide a health benefit. It is also easier than cleaning PM(10) from indoor air, which has proven to be tedious.     

Parametric studies and evaluations of indoor thermal environment in wet season using a field survey and PMV-PPD method

Fanger's PMV-PPD is the most famous thermal sensation indices but it is too complex to be applied in practice. To obtain simple and applicable correlations, taking Qujing of Yunnan province, China, as example, a wet season (six-month) field measurement was conducted in a naturally ventilated residential room. Based on collected data, PMV indices were calculated by using Newton's iterative method. It is shown that the PMV values approximately vary from −1.0 to +1.0 and the indoor thermal environment is basically comfortable. Relationships of the parameters (indoor and outdoor air temperatures, mean radiant temperature, PMV and PPD) and indoor air temperature gradients (vertical and horizontal) were also studied by means of the linear regression and the quadratic polynomial fit techniques. Numerous correlations with high relativities have been developed. Moreover, the vertical and horizontal air temperature gradients range from 0.1 K/m to 0.85 K/m and from −0.208 K/m to 0.063 K/m in wet season. It is convenient to use these results to evaluate and assess the indoor thermal environment under similar climatic conditions. The results of this work enrich and develop the basic theory of the indoor thermal environment design and control.     

Polycyclic and nitro musks in indoor air: a primary school classroom and a women's sport center

Indoor air gas and particulate-phase samples (PM(2.5) ) were collected from a primary school classroom and a women's sport center because children are one of the sensitive population subgroups and women are frequent users of personal care products in addition to the high level of activity in this specific microenvironment. PM(2.5) was collected with a Harvard impactor, and polyurethane foam was used for the gas phase. Samples were ultrasonically extracted, concentrated, and analyzed with a GC-MS. The mean gas-phase concentrations in the classroom ranged from 0.12 ± 0.2 ng/m(3) for MK to 267 ± 56?ng/m(3) for HHCB, while it was from 0.08 ± 0.10 ng/m(3) for AHMI to 144 ± 61 ng/m(3) for HHCB in the sports center. Particulate-phase average concentrations in the sports center ranged from 0.22 ± 0.11 ng/m(3) for ATII to 1.34 ± 071 ng/m(3) for AHTN, while it ranged from 0.05 ± 0.02 ng/m(3) (musk xylene) to 2.50 ± 0.94 ng/m(3) (HHCB) in the classroom. Exposure-risk assessment showed that inhalation route is most probably far less significant than the dermal route; however, it should be noted that the exposure duration covered in this study was not the larger fraction of the day. PRACTICAL IMPLICATIONS: Synthetic musk compounds (SMCs) are found everywhere because their use in household and personal care products (laundry detergents, carpet cleaners, cleaning agents, fabric softener soaps, shampoos, cosmetics, etc.) has been increasing. These compounds are semi-volatiles that may result in direct and indirect exposures through inhalation route. Although SMCs were found to be dominant in the gas phase, exposure via inhalable particles may be important as we found several compounds in the particulate phase (PM(2.5)).     

Cleaning practices and cleaning products in nurseries and schools: to what extent can they impact indoor air quality?

In the framework of a nationwide survey on indoor air quality conducted from September 2009 to June 2011 in 310 nurseries, kindergartens, and elementary schools in all regions of France, cleaning practices and products were described through an extensive questionnaire completed on‐site by expert building inspectors. The questionnaire included the cleaning frequencies and periods, cleaning techniques, whether windows were open during cleaning, and the commercial names of the products used. Analysis of the questionnaire responses showed that cleaning was generally performed daily for furniture and floors. It was performed mostly in the evening with wet mopping and with one or more windows open. Five hundred eighty‐four different cleaning products were listed, among which 218 safety data sheets (SDSs) were available and analyzed. One hundred fifty‐two chemical substances were identified in the SDSs. The typical substances in cleaning products included alcohols, chlorides, terpenes, aldehydes, and ethers; more than half of them are irritants. Two endocrine disruptors, 2‐phenylphenol and Galaxolide, were identified in two cleaning products used every day to clean the floors, in seven kindergartens and in a nursery respectively. Eleven reactive substances containing C=C double bonds, mostly terpenes, were identified in a wide variety of cleaning products.     

Formaldehyde and acetaldehyde exposure mitigation in US residences: in‐home measurements of ventilation control and source control

Measurements were taken in new US residences to assess the extent to which ventilation and source control can mitigate formaldehyde exposure. Increasing ventilation consistently lowered indoor formaldehyde concentrations. However, at a reference air exchange rate of 0.35 h^?1, increasing ventilation was up to 60% less effective than would be predicted if the emission rate were constant. This is consistent with formaldehyde emission rates decreasing as air concentrations increase, as observed in chamber studies. In contrast, measurements suggest acetaldehyde emission was independent of ventilation rate. To evaluate the effectiveness of source control, formaldehyde concentrations were measured in Leadership in Energy and Environmental Design (LEED)‐certified/Indoor airPLUS homes constructed with materials certified to have low emission rates of volatile organic compounds (VOC). At a reference air exchange rate of 0.35 h^?1, and adjusting for home age, temperature and relative humidity, formaldehyde concentrations in homes built with low‐VOC materials were 42% lower on average than in reference new homes with conventional building materials. Without adjustment, concentrations were 27% lower in the low‐VOC homes. The mean and standard deviation of formaldehyde concentration was 33 μg/m³ and 22 μg/m³ for low‐VOC homes and 45 μg/m³ and 30 μg/m³ for conventional.     

Building‐related health symptoms and classroom indoor air quality: a survey of school teachers in New York State

Most previous research on indoor environments and health has studied school children or occupants in non‐school settings. This investigation assessed building‐related health symptoms and classroom characteristics via telephone survey of New York State school teachers. Participants were asked about 14 building‐related symptoms and 23 classroom characteristics potentially related to poor indoor air quality (IAQ). Poisson regression analysis was used to assess the relationship between these symptoms and each classroom characteristic, controlling for potential confounders. About 500 teachers completed the survey. The most frequently reported classroom characteristics included open shelving (70.7%), food eaten in class (65.5%), dust (59.1%), and carpeting (46.9%). The most commonly reported symptoms included sinus problems (16.8%), headache (15.0%), allergies/congestion (14.8%), and throat irritation (14.6%). Experiencing one or more symptoms was associated most strongly with reported dust (relative risk (RR) = 3.67; 95% confidence interval (CI): 2.62–5.13), dust reservoirs (RR = 2.13; 95% CI: 1.72–2.65), paint odors (RR = 1.73; 95% CI: 1.40–2.13), mold (RR = 1.71; 95% CI: 1.39–2.11), and moldy odors (RR = 1.65 95% CI: 1.30–2.10). Stronger associations were found with increasing numbers of reported IAQ‐related classroom characteristics. Similar results were found with having any building‐related allergic/respiratory symptom. This research adds to the body of evidence underscoring the importance to occupant health of school IAQ.     

Optimization of PMA‐qPCR for Staphylococcus aureus and determination of viable bacteria in indoor air

Staphylococcus aureus may cause infections in humans from mild skin disorders to lethal pneumonia. Rapid and accurate monitoring of viable S. aureus is essential to characterize human exposure. This study evaluated quantitative PCR (qPCR) with propidium monoazide (PMA) to quantify S. aureus. The results showed comparable S. aureus counts between exclusively live cells and mixtures of live/dead cells by qPCR with 1.5 or 2.3 μg/mL PMA (P>.05), illustrating the ability of PMA‐qPCR to detect DNA exclusively from viable cells. Moreover, qPCR with 1.5 or 2.3 μg/mL PMA performed optimally with linearity over 10³‐10⁸ CFU/mL (R²≥0.9), whereas qPCR with 10, 23 or 46 μg/mL PMA significantly underestimated viable counts. Staphylococcus aureus and total viable bacteria were further determined with PMA‐qPCR (1.5 μg/mL) from 48 samples from a public library and two university dormitories and four from outside. Viable bacteria averaged 1.9×10⁴ cells/m³, and S. aureus were detected in 22 (42%) samples with a mean of 4.4×10³ cells/m³. The number of S. aureus and viable bacteria were positively correlated (r=.61, P<.005), and percentages of S. aureus relative to viable bacteria averaged 12‐44%. The results of field samples suggest that PMA‐qPCR can be used to quantify viable S. aureus cells.     

Perceived indoor air quality in naturally ventilated primary schools in the UK: Impact of environmental variables and thermal sensation

Indoor air quality (IAQ) in classrooms has a significant impact on children's academic performance, health, and well-being; therefore, understanding children's perception of IAQ is vital. This study investigates how children's perception of IAQ is affected by environmental variables and thermal sensation. In total, 29 naturally ventilated classrooms in eight UK primary schools were selected and 805 children were surveyed during non-heating and heating seasons. Results show that air sensation votes (ASVs) are more correlated to CO₂ levels than to operative temperatures (T_op) during non-heating seasons and more correlated to T_op than CO₂ levels during heating seasons. The impact of T_op on ASVs decreases with an increase in CO₂ levels, and the effect of CO₂ levels on ASVs decreases with increase in T_op. The most favorable ASVs are given when children feel “cool” and have “as it is” preference. By keeping CO₂ < 1000 ppm and T_op within children's thermal comfort band, ASVs are improved by 43%. The study recommends that standards should consider the impact of both temperature and CO₂ levels on perceived IAQ. Perception of IAQ also affects children's overall comfort and tiredness levels; however, this influence is more significant on tiredness level than that on overall comfort level.     

Inflammatory potential in relation to the microbial content of settled dust samples collected from moisture‐damaged and reference schools: results of HITEA study

Aiming to identify factors causing the adverse health effects associated with moisture‐damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture‐damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples (n = 25) collected from moisture‐damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide (NO), tumor necrosis factor‐α (TNF‐)α, interleukin (IL)‐6, and macrophage inflammatory protein (MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3‐hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture‐damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL‐6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram‐positive bacteria.     

Semi‐volatile organic compounds in the air and dust of 30 French schools: a pilot study

The contamination of indoor environments with chemical compounds released by materials and furniture, such as semi‐volatile organic compounds (SVOCs), is less documented in schools than in dwellings—yet children spend 16% of their time in schools, where they can also be exposed. This study is one of the first to describe the contamination of the air and dust of 90 classrooms from 30 nursery and primary schools by 55 SVOCs, including pesticides, phosphoric esters, musks, polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), phthalates, and polybromodiphenylethers (PBDEs). Air samples were collected using an active sampling method, and dust samples were collected via two sampling methods (wiping and vacuum cleaning). In air, the highest concentrations (median >100 ng/m³) were measured for diisobutyl phthalate (DiBP), dibutyl phthalate (DBP), diethyl phthalate (DEP), bis(2‐ethylhexyl) phthalate (DEHP), and galaxolide. In dust, the highest concentrations (median >30 μg/g) were found for DEHP, diisononyl phthalate (DiNP), DiBP, and DBP. An attempt to compare two floor dust sampling methods using a single unit (ng/m²) was carried out. SVOC concentrations were higher in wiped dust, but frequencies of quantification were greater in vacuumed dust.     

A randomized double‐blind crossover study of indoor air filtration and acute changes in cardiorespiratory health in a First Nations community

Few studies have examined indoor air quality in First Nations communities and its impact on cardiorespiratory health. To address this need, we conducted a crossover study on a First Nations reserve in Manitoba, Canada, including 37 residents in 20 homes. Each home received an electrostatic air filter and a placebo filter for 1 week in random order, and lung function, blood pressure, and endothelial function measures were collected at the beginning and end of each week. Indoor air pollutants were monitored throughout the study period. Indoor PM_2.5 decreased substantially during air filter weeks relative to placebo (mean difference: 37 μg/m³, 95% CI: 10, 64) but remained approximately five times greater than outdoor concentrations owing to a high prevalence of indoor smoking. On average, air filter use was associated with a 217‐ml (95% CI: 23, 410) increase in forced expiratory volume in 1 s, a 7.9‐mm Hg (95% CI: ?17, 0.82) decrease in systolic blood pressure, and a 4.5‐mm Hg (95% CI: ?11, 2.4) decrease in diastolic blood pressure. Consistent inverse associations were also observed between indoor PM_2.5 and lung function. In general, our findings suggest that reducing indoor PM_2.5 may contribute to improved lung function in First Nations communities.