Indoor Particulate Matter Levels Research Articles

Patterns and disparities in indoor particulate matter levels in selected primary schools in Kigali, Rwanda

Air pollution is a global environmental and public health challenge. There is limited evidence about the air quality in Rwanda, and the concentrations of particulate matter (PM), namely PM2.5 and PM10 in schools have not been well documented. This study evaluated patterns and disparities in indoor PM levels in selected primary schools in Kigali, Rwanda.The study collected PM2.5 and PM10 concentrations from six classrooms in six selected primary schools during the regular school study period in the dry season. Data were collected using mobile air sensors (purple air/PA–II–SD air quality) and an observation checklist. A Kruskal-Wallis test was performed to assess the difference in PM2.5 and PM10 concentrations between the six schools. The post-hoc Mann-Whitney test was used to compare all group pairs.The results indicated a significant difference in both the indoor PM2.5 concentration (H (5) = 41.01, p < 0.001) and the indoor PM10 concentration (H (5) = 38.5, p < 0.001). The maximum concentration observed was 133.6 μg/m3 for PM2.5 and 158.5 μg/m3 for PM10. Schools in highly exposed areas tended to have higher concentrations of PM than schools in moderately exposed areas. Specifically, the daily average concentration of PM2.5 in schools located in highly exposed areas ranged from 39 μg/m³ to 118 μg/m³, while PM10 levels ranged from 44.0 μg/m³ to 126 μg/m³. In contrast, schools in moderately exposed areas had daily PM2.5 average concentrations ranging from 32.0 μg/m³ to 111.0 μg/m³ and daily PM10 average concentrations ranging from 38.0 μg/m³ to 119 μg/m³.Overall, the recorded values for both PM2.5 and PM10 in all sampled schools were higher than the World Health Organization air quality guidelines. Indoor air quality is poorer in schools situated in highly exposed areas. This study suggests interventions to improve school air quality for the benefit of school communities.

Assessing the risks associated with indoor and outdoor air quality in relation to the geographic placement of nursing home

Indoor air quality significantly impacts the well-being and health of elderly residents in nursing homes. This study was conducted to explore the connection between indoor and outdoor PM (Particulate Matter) concentrations in nursing homes and their association with the facilities' location and construction characteristics. The findings revealed that indoor PM2.5 and PM10 concentrations ranged from 0.2 to 124 μg/m3 and 2–188.4 μg/m3, respectively, which were approximately 12.67 and 1.25 times higher than their outdoor counterparts. A strong correlation (P < 0.05) was identified between indoor PM levels and various factors, including proximity to parks, passenger terminals, and gas stations, as well as building attributes such as single-glazed windows, ceramic floor coverings, and the use of radiators. The risk assessment indicated that carcinogenic risk factors were well within acceptable limits for all nursing homes. However, it's important to note that certain PM components, particularly polycyclic aromatic hydrocarbons (PAH), may have long-term adverse effects on the health of nursing home residents. Even though indoor PM levels met the standards established by the U.S. Environmental Protection Agency (USEPA) for particulate matter risk assessments, the study emphasized that even low levels of indoor air pollutants can affect the health and well-being of older adults, particularly considering the increased vulnerability associated with aging. Consequently, the study underscores the importance of nursing home location selection and the regular monitoring of particulate matter concentrations. These measures are essential for enhancing air quality within nursing homes, ultimately contributing to the improved well-being and health of their residents.

Lung deposition of PM-bound trace elements and corresponding human health risk assessment in commercial kitchens serving Mediterranean cuisine

The service offered by commercial kitchens and the catering industry is becoming more and more popular all around the world. However, the health risks of sector workers are often overlooked. In this study, size-segregated Particulate Matter (PM) samples were collected from the indoor environments of five commercial kitchens, and elemental concentrations were quantified to estimate the corresponding health risks. Lung-deposited fractions of trace elements in three different regions of the respiratory tract were estimated and used to assess carcinogenic and non-carcinogenic health risks. Besides, the deterioration in lung capacity of the cooks was also evaluated by spirometry tests to correlate indoor pollutants. Exposure to trace elements was dominated by Na, S, Al, Fe, and Mg. Estimated carcinogenic risk through inhalation exposure to Cr was between the moderate risk level of 10−6 to 10−4, while the Hazard Index (HI) values were lower than the acceptable level of 1. This, along with elevated indoor PM levels, represented a significant potential for carcinogenic health hazards for the kitchen staff. According to the results of the lung function tests, a significant decrease was determined in the respiratory functions of the cooks, and it was associated with elevated exposure to fine PM, Pb, Cr, Cu, K, Ni, and Mn. Workplace health and safety measures to better protect the health of kitchen staff are urgently needed and should attract more public attention.

Assessment of Indoor Particulate Matter and Teacher's Perceived Indoor Climate in Government Schools of Bilaspur District, Chhattisgarh, India: A Cross-Sectional Study.

Indoor air pollution (IAP) affects the long-term health, cognitive growth, and academic performance of children. Since children spend most of their time at school, quantifying IAP in classrooms is an important parameter for air pollution. To assess the average particulate matter (PM) levels inside and outside of classrooms along with their associated factors and teacher's perceived indoor climate. Cross-sectional survey in nine government-run schools. PM2.5 and PM10 were measured inside the classroom and outdoors simultaneously during summers, using an Atmos monitor for two consecutive days, along with several school and classroom characteristics. Perception about indoor air quality was captured from teachers (n = 15) using a validated questionnaire. Mean values of PM using mixed effect linear regression. Perceived indoor air quality is presented using percentages. Mean indoor PM2.5 and PM10 was 52.5 µg/m3 and 65 µg/m3. Indoor and outdoor PM levels were highly correlated, but the indoor-outdoor ratio of PM concentrations was more than 1. Teachers were mostly bothered by dust, dirt, and noise in the schools. Indoor air quality was higher than World Health Organization (WHO) standards but within the national standards. Need further research to find the exact cause for higher indoor PM levels compared to outdoor PM levels.

Effectiveness of plants for passive removal of particulate matter is low in the indoor environment

Particulate air pollution is a major health concern and is responsible for about one in nine premature deaths worldwide. Significant exposure to particulate matter (PM) may happen indoors because people spend a large fraction of their time inside buildings. Indoor plants have been suggested as a potential solution for removing PM; however, their effectiveness has not been well characterized. We quantified the ability of eleven different plant species to remove airborne PM through experiments conducted in an environmental chamber. By introducing PM into the chamber and measuring its removal rate with and without the plants, we estimated plants’ deposition velocities and clean air delivery rates (CADRs).The average deposition velocities were 93 ± 9 cm/h for the moss plant, between 29 ± 3 cm/h to 37 ± 4 cm/h for the needle-leaved plants, and between 1 ± 2 cm/h to 13 ± 2 cm/h for the broad-leaved plants. Their CADRs were between 0.002 ± 0.004 m3/h to 0.084 ± 0.009 m3/h, which were significantly lower than those of filter-based air purifiers (CADRs = 170–800 m3/h), meaning that passive plant systems cannot compete with conventional air purifiers. We also found that large quantities of plants would be required to achieve even modest reductions in indoor PM concentrations under real-world conditions, thus highlighting their limited role in controlling indoor PM levels.

Levels of indoor particulate matter and association with asthma in children in Benin City, Nigeria.

The relationship between indoor particulate matter and asthma in children was assessed in this study. Forty-five (45) locations were randomly selected across the five local government areas in Benin City, Edo State, for air quality assessment. Indoor and outdoor particulates (PM1.0, PM2.5, and PM10) were monitored monthly using a handheld BLATN particulate sampler (Br-Smart-126S series). Reported clinical cases of asthma in children from 2008 to 2017 were collected from two major hospitals in the metropolis. The data obtained were analysed with SPSS for Windows version 21.0. The average concentrations of indoor and ambient PM ranged between 10.7-26.2 and 19.0-49.4µg/m3 (PM1.0), 27.4-59.6 and 45.6-93.0µg/m3 (PM2.5), and 33.5-67.9 and 60.9-106.1µg/m3 (PM10) in the wet and dry seasons. PM2.5 and PM10 concentrations were observed above the WHO standards. Indoor particulate concentration was significantly (p = 0.001-0.012) higher in the dry season across the locations. Outdoor PM correlated positively (R = 0.568-0.855, p < 0.05; R2 = 0.322-0.724, p < 0.001) with their corresponding indoor PM concentration. The hazard ratio (HR) values of PM2.5 and PM10 exceeded 1 in all the sampling locations during the dry season, while the mean total hazard ratio (THR) of both PM metrics was considerably higher during the dry season than in the wet season. Indoor PM concentrations showed a significant positive correlation with reported cases of asthma (R = 0.498-0.542, p < 0.001) and accounted for 40.6% of the asthma cases during the dry season. The study showed that children in the selected households are at risk of increased asthma exacerbation due to exposure to particulate matter pollution.

An extended analysis of cardiovascular benefits of indoor air filtration intervention among elderly: a randomized crossover trial (Beijing indoor air purifier study, BIAPSY)

ObjectiveEvidence on potential cardiovascular benefits of personal-level intervention among the elderly exposed to high levels of particulate matter (PM) remains limited. We aimed to assess improvements in surrogate markers of cardiovascular injury in vulnerable populations at risks by using indoor air filtration units. MethodsWe conducted a randomized crossover trial for 2 separate 2-week air filtration interventions in 20 households of patients with stable chronic obstructive pulmonary disease and their partners in the winter of 2013, with concurrent measurements of indoor PM. The changes in biomarkers indicative of cardiac injury, atherosclerosis progression and systemic inflammation following intervention were evaluated using linear mixed-effect models. ResultsIn the analysis, average levels of indoor PM with aerodynamic diameters < 2.5 µm (PM2.5) decreased significantly by 59.2% (from 59.6 to 24.3 µg/m3, P < 0.001) during the active air filtration. The reduction was accompanied by improvements in levels of high-sensitivity cardiac troponin I by −84.6% (95% confidence interval [CI]: −90.7 to −78.6), growth differentiation factor-15 by −48.1% (95% CI: −31.2 to −25.6), osteoprotegerin by −65.4% (95% CI: −56.5 to −18.7), interleukin-4 by −46.6% (95% CI: −62.3 to −31.0) and myeloperoxidase by −60.3% (95% CI: −83.7 to −3.0), respectively. ConclusionIndoor air filtration intervention may provide potential cardiovascular benefits in vulnerable populations at risks.

Efficacy of air purifier therapy for patients with allergic asthma.

This study aimed to evaluate the efficacy of air purifier therapy for patients with allergic asthma. Thirty-eight subjects were categorized under two groups namely treatment group and control group. All subjects were under 18 years of age and they had been clinically diagnosed with allergic asthma. The treatment group used high efficiency particulate air (HEPA) purifiers for six consecutive months, and the control group did not use the air filters. Particulate matter (PM) data and dust samples (from bedding and a static point) were collected from the subjects' bedrooms before they started using the air purifiers and each month thereafter. Simultaneously, the subjects were asked to complete a questionnaire for the Asthma Control Test (ACT) or Childhood Asthma Control Test (C-ACT). Fractional exhaled nitric oxide (FENO) tests were performed at the start and end of the study. The concentrations of Der p1 and Der f1 were measured in the dust samples. (1) After utilizing the air purifier, the concentrations of house dust mite (HDM) allergens (Der p1+ Der f1) in the dust samples decreased. In addition, the PMindoor/outdoor values significantly decreased. (2) The ACT and C-ACT scores in the treatment group maintained a steady significant upward trend. (3) At the end of the study, the FENO levels in both groups were lower, although the differences were not significant. It is witnessed that HEPA air purifiers can decrease indoor HDM allergen and PM levels and improve the quality of life for allergic asthma patients.

Performance Evaluation of Particulate Matter and Indoor Microclimate Monitors in University Classrooms under COVID-19 Restrictions.

Optical monitors have proven their versatility into the studies of air quality in the workplace and indoor environments. The current study aimed to perform a screening of the indoor environment regarding the presence of various fractions of particulate matter (PM) and the specific thermal microclimate in a classroom occupied with students in March 2019 (before COVID-19 pandemic) and in March 2021 (during pandemic) at Valahia University Campus, Targoviste, Romania. The objectives were to assess the potential exposure of students and academic personnel to PM and to observe the performances of various sensors and monitors (particle counter, PM monitors, and indoor microclimate sensors). PM1 ranged between 29 and 41 μg m−3 and PM10 ranged between 30 and 42 μg m−3. It was observed that the particles belonged mostly to fine and submicrometric fractions in acceptable thermal environments according to the PPD and PMV indices. The particle counter recorded preponderantly 0.3, 0.5, and 1.0 micron categories. The average acute dose rate was estimated as 6.58 × 10−4 mg/kg-day (CV = 14.3%) for the 20–40 years range. Wearing masks may influence the indoor microclimate and PM levels but additional experiments should be performed at a finer scale.

Assessment of Particulate Matter Levels in Homes with Children

Children’s exposure to particulate matter (PM) is of great interest because it can cause adverse health effects, including asthma, and decreased lung function. The purpose of this study was to determine the levels of PM in low socio-economic status homes in Omaha, Nebraska. Between October 2018 and September 2019, we collected ambient air PM samples from 30 homes, of which 70% had at least one asthmatic child. Samples were collected at the 2-foot level and the 4-foot level to approximate the breathing zones of toddlers and older children, respectively. We also asked the study participants questions related to indoor air quality (IAQ). Indoor PM levels ranged from 4.28 to 72.81 μg/m3. There was a significant association between IAQ and the furnace filter status (dirty or clean) (p = 0.023, OR = 7.5 [95% confidence interval: 1.40, 39.84]). We found that IAQ status suggests a significant association with the level of housekeeping (p = 0.05, OR = 4.76 [95% confidence interval: 0.95, 23.86]). Indoor PM levels varied significantly between 2 feet and 4 feet (p &lt; 0.05). PM levels could differ substantially depending on the furnace filter’s status. In addition, exposure to PM can significantly depend on the child’s height.

Comparative Analysis of Indoor and Outdoor Particulate Matter Concentrations and Air Quality in Ogbomoso, Nigeria

Background.Airborne particulates are an issue in many urban regions around the world and their detrimental impact on human health has increasingly become a public health concern.Objectives.The aim of the present study was to examine particle pollution in an urban settlement in Nigeria. This study examines the extent, spatial variation, and sources of indoor and outdoor particulate matter (PM) concentrations in Ogbomoso, Nigeria.Methods.The survey research method was adopted. Sampling included 385 buildings across selected precincts and different residential zones in the town of Ogbomoso. Particulate matter analytes (PM1, PM2.5 and PM10) within/around each building were measured with a particle counter and details on domestic utilities/practices were obtained with a questionnaire. Analysis of variance was used to determine inter-zonal variations in PM levels and simple linear regression was used to analyze the relationship between indoor and outdoor air quality.Results.Indoor and outdoor respirable particle (PM2.5) concentrations were lower than the World Health Organization (WHO) Interim Target limit of 75 μg/m3, while concentrations of inhalable particles (PM10) were higher than the set limit of 150 μg/m3 for daily averages. Coarse particles dominated, with an accumulative PM2.5/PM10 ratio of 0.24. The inter-zonal analysis of PM concentrations revealed that indoor and outdoor PM levels varied significantly by residential zone (p = 0.0005; p = 0.01, respectively). Regression analysis showed a significant but weak relationship between indoor and outdoor PM levels (r = +0.221), while the coefficient of determination (R2 = 0.049) showed that only about 5% of the variation in indoor air quality was associated with outdoor air quality. Particle pollution inducers were identified in the residents' waste disposal methods and adopted fuels/energy sources, with firewood and charcoal linked with increased concentrations of particulate matter.Conclusions.Air quality was relatively poor in the study area given observed particulate matter concentrations. Cleaner fuels, effective waste management systems and improved roads are needed to foster better air quality in the study area.Competing Interests.The authors declare no competing financial interests

Canaries at the Climbing Wall: A Comparative Study of Particulate Matter at Two University Climbing Walls

Magnesium alba—chalk—is regularly applied by indoor and outdoor climbers to their hands to reduce sweat while climbing in order to grip climbing holds. We investigated the potential for suspended chalk dust to lead to unhealthy levels of indoor particulate matter (PM2.5 and PM10) in two university climbing facilities. Low-cost, Dylos DC 1700 PM monitors sampled air quality during two, 5-day sampling periods. Findings revealed “good” PM values at one university climbing facility and “unhealthy” (PM2.5) or “very unhealthy” (PM10) values at the other institution’s climbing wall. Facility predicted over 60% of the variance in PM readings, and post hoc tests revealed 75% of the variance in PM values at the second institution can be explained by open climbing hours. These findings hold a variety of implications for future research and management of university climbing wall facilities to ensure the health of staff and their patrons.

Comparative Indoor Pollution from Glo, Iqos, and Juul, Using Traditional Combustion Cigarettes as Benchmark: Evidence from the Randomized SUR-VAPES AIR Trial.

Modified risk products (MRP) such as electronic vaping cigarettes (EVC) and heat-not-burn cigarettes (HNBC) are appealing alternatives to combustion cigarettes. Limited between- and within-device comparative data are available on MRP. We aimed at comparing indoor particulate matter (PM) emissions measured in a randomized trial enforcing standardized smoking sessions, testing different devices and flavors of MRP, using traditional combustion cigarettes (TCC) as benchmark. Overall, MRP yielded significantly lower levels of indoor PM in comparison to TCC (with median PM levels during smoking for MRP < 100 μg/m3, and for TCC > 1000 μg/m3). Despite this, significant differences among MRP were found, with Iqos appearing associated with a significantly lower burden of emissions for all the monitored fractions of PM, including total PM (all p < 0.05). Precisely, during use, PM ≤1 µm (PM1) emissions were 28 (16; 28) μg/m3 for Glo, 25 (15; 57) μg/m3 for Iqos, and 73 (15; 559) μg/m3 for Juul (p < 0.001 for Glo vs. Iqos, p < 0.001 for Glo vs. Juul, and p = 0.045 for Iqos vs. Juul). Exploratory within-MRP analyses suggested significant differences between flavors, favoring, for instance, Ultramarine for Glo, Bronze for Iqos, and Mango for Juul, even if results varied substantially according to individual smoker. In conclusion, leading MRP have significantly less intense and persistent effects on indoor pollution in comparison to TCC. Yet, when focusing solely on MRP, between-product and between-flavor differences appear, with quantitative estimates suggesting lower polluting effects with Iqos. These results, if confirmed externally, could be used to individualize product and flavor choice to minimize the untoward effects of EVC and HNBC on indoor pollution.

How Do Combustion and Non-Combustion Products Used Outdoors Affect Outdoor and Indoor Particulate Matter Levels? A Field Evaluation Near the Entrance of an Italian University Library.

Particulate Matter (PM) is a well-known health risk factor and pollutes both outdoor and indoor air. Using PM as an air pollution indicator, the aims were to assess outdoor and indoor air pollution due to combustion and/or non-combustion products used outdoors and to compare the PM levels emitted by different products. PM with an aerodynamic diameter ≤10, 4, 2.5 and 1 µm (PM10, PM4, PM2.5, PM1) was simultaneously measured in two areas, respectively, indoors (with smoking ban) and outdoors (where people commonly smoke) of a university library during the morning and the afternoon of two weekdays. Both combustion and non-combustion products determined a relevant worsening of outdoor air quality, with the highest PM1 levels achieved when a single traditional cigarette (9920 µg m−3), a single e-cigarette (9810 µg m−3) and three simultaneous traditional cigarettes (8700 µg m−3) were smoked. An increase of indoor PM1 levels was found during outdoor smoking/vaping sessions, persisting also after the end of sessions. The results highlighted the need for a revision of smoke-free laws, especially for outdoor areas, to include non-combustion products. In addition, it is essential to make society aware of the dangers of smoking outdoors by implementing health promotion interventions.

Prospective Association of Air-Purifier Usage during Pregnancy with Infant Neurodevelopment: A Nationwide Longitudinal Study-Japan Environment and Children's Study (JECS).

Fetal exposure to particulate matter (PM) is associated with infant developmental delay likely via neuroinflammation and prefrontal cortex lesions; however, whether air-purifier usage, which can reduce indoor PM levels, is related to infant developmental delay remains unknown. We therefore examined the prospective relationship between air-purifier usage during pregnancy and infant developmental delay by analyzing 82,441 mother–infant pairs using a simple yes/no questionnaire. Developmental delays at 6 and 12 months were assessed in five areas using the Ages and Stages Questionnaire, Third Edition. A generalized linear mixed model analysis was used to derive adjusted odds ratios (AORs) and 95% confidence intervals (95% CIs) while controlling for 20 covariates. The analysis revealed that air-purifier usage was associated with developmental delays in fine motor (AOR: 0.91, 95% CI: 0.83–0.99) and problem solving (AOR: 0.83, 95% CI: 0.77–0.90) at 6 months and in communication (AOR: 0.86, 95% CI: 0.79–0.93), fine motor (AOR: 0.87, 95% CI: 0.82–0.92), problem solving (AOR: 0.83, 95% CI: 0.77–0.88), and personal–social (AOR: 0.79, 95% CI: 0.72–0.86) at 12 months. In conclusion, a negative association exists between air-purifier usage during pregnancy and infant neurodevelopmental delay that strengthens with time. Our results outline the potential role of air purifiers in inhibiting infant neurodevelopmental delay.

Exposure Assessment of Indoor PM Levels During Extreme Dust Episodes.

Millions of people live in areas that are subject to frequent dust events; however gaps remain in our knowledge about the association between dust, air quality and corresponding particulate matter (PM) exposure levels inside buildings. This case study demonstrates how the PM2.5 and PM10 levels in an urban environment respond to strong natural dust episodes. Real-time measurements were recorded simultaneously in indoor and outdoor environments in households in the city of Beer-Sheva, Israel during several strong dust events. A typical strong event was used for a detailed analysis of PM10 and PM2.5. Outdoor daily concentrations were above 1000 µg m−3 for PM10, the maximum hourly value of which was 1320 µg m−3. The indoor PM10 peaked at about 700 µg m−3 and fluctuated in parallel with the outdoor level but with a time lag of about 15 min. Indoor air tended to remain for several hours after the dust event had subsided. Analyses of multiple events revealed that the dependence of indoor PM2.5 and PM10 on natural dust varies but is not directly linked to the level of atmospheric dust concentration. From a health perspective, the exposure risk posed by extreme indoor PM2.5 and PM10 levels generated by natural dust episodes should be considered.

Metal-containing Particulate Matter and Associated Reduced Olfactory Identification Ability in Children from an Area of High Atmospheric Exposure in Mexico City.

Air pollution has been linked to poor olfactory function in human adults. Among pollutants, particulate matter (PM) is especially relevant, as it may contain toxic metal ions that can reach the brain via olfactory pathways. Our purpose was to investigate the relation between atmospheric PM and olfactory identification performance in children. Using a validated method, we tested the olfactory identification performance of 120 children, 6-12 years old, from two locations in Mexico City: a focal group (n = 60) from a region with high PM levels and a control group of equal size and similar socioeconomic level from a region with markedly lower PM concentrations. Groups were matched for age and sex. Concentrations of manganese and lead in the hair of participants were determined as biomarkers of exposure. Daily outdoor PM levels were obtained from official records, and indoor PM levels were measured in the children's classrooms. Official records confirmed higher levels of outdoor PM in the focal region during the days of testing. We also found higher classroom PM concentrations at the focal site. Children from the focal site had on average significantly lower olfactory identification scores than controls, and hair analysis showed significantly higher levels of manganese for the focal children but no difference in lead. Children appear to be vulnerable to the effects of air pollution on olfactory identification performance, and metal-containing particles likely play a role in this. Olfactory tests provide a sensitive, noninvasive means to assess central nervous function in populations facing poor air quality.

Effects of air cleaners and school characteristics on classroom concentrations of particulate matter in 34 elementary schools in Korea

Exposure to particulate matter (PM) in school environments has been associated with respiratory illnesses among children. Although using air cleaners was reported to reduce PM exposure and improve residents' health in homes, their effects in classrooms are not well understood. We examined how the use of air cleaners in classrooms and school/classroom characteristics affect the levels of indoor PM. Our environmental study included 102 classrooms from 34 elementary schools located on the mainland peninsula and an island in Korea. Indoor and outdoor PM were monitored simultaneously with portable aerosol spectrometers, and indoor gravimetric PM levels were measured with low volume, size-selective samplers during the class hours. Correlations among PM measurements were computed and final multiple regression models for indoor PM were constructed with a model building procedure. Correlation between indoor and outdoor PM2.5 (PM < 2.5 μm in aerodynamic diameter) was higher (r = 0.78, p < 0.01) than that of PM10 (PM < 10 μm) (r = 0.49, p < 0.01). School location, classroom occupant density, and ambient PM levels significantly (p-values<0.05) affected classroom PM concentrations. The adjusted PM levels in classrooms using air cleaners were significantly (p-values<0.01) lower by approximately 35% than in classrooms not using them. However, air cleaners appeared to remove PM2.5 more effectively than PM10, perhaps because coarse particles settle more rapidly than fine particles on surfaces, or their resuspension and generation rate by occupants exceeds the removal rate by air cleaners. Our study suggests that routine cleaning to remove surface dust along with the use of air cleaners might be required to effectively reduce occupants’ exposure in classrooms.

Particulate matter in residential buildings in New Zealand: Part II. The impact of building airtightness, mechanical ventilation using simulated occupancy

Abstract Many occupant activities can adversely affect indoor air quality which has been shown to be detrimental to human health. This research eliminated some of the variability of previous measured levels of indoor particulate matter (PM) by removing all human activity and providing baseline data on the contribution occurring from home furnishings. Further objectives included investigating the effects of airtightness and mechanical ventilation on internal PM concentrations with controlled simulated occupancy. With natural ventilation, PM concentrations were 15% greater in bedroom of the less airtight (Control) house than that of the (Test house), post-furnishing which indicates that there is a considerable amount of natural variation which may not be solely due to occupant activities. Simulated occupancy dramatically increased the concentration of PM found in both houses by just under 5-fold. With simulated occupancy, the majority of the PM was present as fine particles (≤PM1) for both houses (93–94%), whereas without simulated occupancy, the proportion of fine particles was lower (88–89%). After furnishing and without the use of mechanical ventilation, PM10 concentrations exceeded the WHO Guidelines for PM10 of 50 μg m−3 for 56% of the testing duration for the Control bedroom and 35% for the Test bedroom. The use of mechanical ventilation reduced the mean internal PM concentrations by approximately 90% for all PM sizes in both study bedrooms which highlights the importance of use and maintenance of effective ventilation systems especially after furnishing activities.

Indoor particulate matter and lung function in children

People generally spend more time indoors than outdoors resulting in a higher proportion of exposure to particulate matter (PM) occurring indoors. Consequently, indoor PM levels, in contrast to outdoor PM levels, may have a stronger relationship with lung function.To test this hypothesis, indoor and outdoor PM2.5 and fungal spore data were simultaneously collected from the homes of forty-four asthmatic children aged 10–16 years. An optical absorption technique was utilized on the collected PM2.5 mass to obtain concentrations of black carbon (BC) and ultraviolet light absorbing particulate matter, (UVPM; a marker of light absorbing PM2.5 emitted from smoldering organics). Enrolled children completed spirometry after environmental measurements were made. Given the high correlation between PM2.5, BC, and UVPM, principal component analysis was used to obtain uncorrelated summaries of the measured PM. Separate linear mixed-effect models were developed to estimate the association between principal components of the PM variables and spirometry values, as well as the uncorrelated original PM variables and spirometry values.A one-unit increase in the first principal component variable representing indoor PM (predominantly composed of UVPM and PM2.5) was associated with 4.1% decrease (99% CI = −6.9, −1.4) in FEV1/FVC ratio. 11.3 μg/m3 increase in indoor UVPM was associated with 6.4% and 14.7% decrease (99% CI = −10.4, −2.4 and 99% CI = −26.3, −2.9, respectively) in percent predicted FEV1/FVC ratio and FEF25–75 respectively. Additionally, 17.7 μg/m3 increase in indoor PM2.5 was associated with 6.1% and 12.9% decrease (99% CI = −10.2, −1.9 and 99% CI = −24.9, −1.0, respectively) in percent predicted FEV1/FVC ratio and FEF25–75, respectively. Outdoor PM, indoor BC, and indoor fungal spores were not significantly associated with lung function.The results indicate that indoor PM is more strongly associated with lung function in children with asthma as compared with outdoor PM.