Exploring relationships between outdoor air particulate-associated polycyclic aromatic hydrocarbon and PM2.5: A case study of benzo(a)pyrene in California metropolitan regions

Polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM) are co-pollutants emitted as by-products of combustion processes. Convincing evidence exists for PAHs as a primary toxic component of fine PM (PM_2.5). Because PM_2.5 is listed by the US EPA as a “Criteria Pollutant”, it is monitored regularly at sites nationwide. In contrast, very limited data is available on measured ambient air concentrations of PAHs. However, between 1999 and 2001, ambient air concentrations of PM_2.5 and benzo(a)pyrene (BaP) are available for California locations. We use multivariate linear regression models (MLRMs) to predict ambient air levels of BaP in four air basins based on reported PM_2.5 concentrations and spatial, temporal and meteorological variables as variates. We obtain an R² ranging from 0.57 to 0.72 among these basins. Significant variables (p<0.05) include the average daily PM_2.5 concentration, wind speed, temperature and relative humidity, and the coastal distance as well as season, and holiday or weekend. Combining the data from all sites and using only these variables to estimate ambient BaP levels, we obtain an R² of 0.55. These R²-values, combined with analysis of the residual error and cross validation using the PRESS-statistic, demonstrate the potential of our method to estimate reported outdoor air PAH exposure levels in metropolitan regions. These MLRMs provide a first step towards relating outdoor ambient PM_2.5 and PAH concentrations for epidemiological studies when PAH measurements are unavailable, or limited in spatial coverage, based on publicly available meteorological and PM_2.5 data.     

Indoor particulate matter in urban residences of Alexandria,Egypt

Indoor particulate matter samples were collected in 17 homes in an urban area in Alexandria during the summer season. During air measurement in all selected homes, parallel outdoor air samples were taken in the balconies of the domestic residences. It was found that the mean indoor PM_2.5 and PM₁₀ (particulate matter with an aerodynamic diameter ≤2.5 and ≤10 μm, respectively) concentrations were 53.5 ± 15.2 and 77.2 ± 15.1 µg/m³, respectively. The corresponding mean outdoor levels were 66.2 ± 16.5 and 123.8 ± 32.1 µg/m³, respectively. PM_2.5 concentrations accounted, on average, for 68.8 ± 12.8% of the total PM₁₀ concentrations indoors, whereas PM_2.5 contributed to 53.7 ± 4.9% of the total outdoor PM₁₀ concentrations. The median indoor/outdoor mass concentration (I/O) ratios were 0.81 (range: 0.43–1.45) and 0.65 (range: 0.4–1.07) for PM_2.5 and PM₁₀, respectively. Only four homes were found with I/O ratios above 1, indicating significant contribution from indoor sources. Poor correlation was seen between the indoor PM₁₀ and PM_2.5 levels and the corresponding outdoor concentrations. PM₁₀ levels were significantly correlated with PM_2.5 loadings indoors and outdoors and this might be related to PM₁₀ and PM_2.5 originating from similar particulate matter emission sources. Smoking, cooking using gas stoves, and cleaning were the major indoor sources contributed to elevated indoor levels of PM₁₀ and PM_2.5.

Implications: The current study presents results of the first PM_2.5 and PM₁₀ study in homes located in the city of Alexandria, Egypt. Scarce data are available on indoor air quality in Egypt. Poor correlation was seen between the indoor and outdoor particulate matter concentrations. Indoor sources such as smoking, cooking, and cleaning were found to be the major contributors to elevated indoor levels of PM₁₀ and PM_2.5.     

Atmospheric Particulate Matter and Polycyclic Aromatic Hydrocarbons for PM10 and Size-Segregated Samples in Bangkok

Abstract

Air samples of particulate matter (PM) with an aerodynamic diameter less than 10 µm (PM₁₀) were collected from six sites in Bangkok, Thailand, using high-volume air samplers. Daily samples were taken at intervals of 12 days from November 1999 to November 2000. Size-selected sampling using a multislit Andersen size-fractionated cascade impactor was undertaken at one site in central Bangkok to identify particulate size distribution. The annual average PM₁₀ concentration at all six sites exceeded the Thailand National Ambient Air Quality Standard (NAAQS) of 50 µg/m³. The daily PM₁₀ concentrations at heavy traffic roadside areas ranged between 30 and 160 µg/m³. The highest PM₁₀ level occurred during the winter period (November–February), which is the dry season. From our results, which are based on a 1-yr survey, it can be observed that the particulate concentrations are associated with traffic volumes and seasonal factors (temperature and rainfall). The relative importance of size fractions in contributing to PM load is presented and discussed. Twenty polycyclic aromatic hydro-carbons (PAHs) associated with PM have been identified and quantified. The summed PAHs based on the 20 species had an average concentration of 60 ng/m³. Benzo(e)pyrene, indeno(123cd)pyrene, and benzo(ghi)perylene were the major compounds with average concentrations of 8, 10, and 13 ng/m³, respectively. Results indicate that more than 97% of PAHs were found in the small particulate size range of <0.95 µm.     

Outdoor and indoor factors influencing particulate matter and carbon dioxide levels in naturally ventilated urban homes

ABSTRACT

The present study investigated indoor and outdoor concentrations of two particulate matter size fractions (PM₁₀ and PM_2.5) and CO₂ in 20 urban homes ventilated naturally and located in one congested residential and commercial area in the city of Alexandria, Egypt. The results indicate that the daily mean PM_2.5 concentrations measured in the ambient air, living rooms, and kitchens of all sampling sites exceeded the WHO guideline by 100%, 65%, and 95%, respectively. The daily mean outdoor and indoor PM₁₀ levels in all sampling sites were found to exceed the WHO guideline by 100% and 80%, respectively. The indoor PM₁₀ and PM_2.5 concentrations were significantly correlated with their corresponding outdoor levels, as natural ventilation through opening doors and windows allowed direct transfer of outdoor airborne particles into the indoor air. Most of the kitchens investigated had higher indoor concentrations of PM_2.5 and CO₂ than in living rooms. The elevated levels of PM_2.5 and CO₂ in domestic kitchens were probably related to inadequate ventilation. The current study attempted to understand the sources and the various indoor and outdoor factors that affect indoor PM₁₀, PM_2.5 and CO₂ concentrations. Several domestic activities, such as smoking, cooking, and cleaning, were found to constitute important sources of indoor air pollution. The indoor pollution caused by PM_2.5 was also found to be more serious in the domestic kitchens than in the living rooms and the results suggest that exposure to PM_2.5 is high and highlights the need for more effective control measures.

Implications: Indoor air pollution is a complex problem that involves many determinant factors. Understanding the relationships and the influence of various indoor and outdoor factors on indoor air quality is very important to prioritize control measures and mitigation action plans. There is currently a lack of research studies in Egypt to investigate determinant factors controlling indoor air quality for urban homes. The present study characterizes the indoor and outdoor concentrations of PM₁₀, PM_2.5, and CO₂ in residential buildings in Alexandria city. The study also determines the indoor and outdoor factors which influence the indoor PM and CO₂ concentrations as well as it evaluates the potential indoor sources in the selected homes. This research will help in the development of future indoor air quality standards for Egypt.     

Airborne particle PM2.5/PM10 mass distribution and particle-bound PAH concentrations near a medical waste incinerator

This study attempts to determine the influence of air quality in a residential area near a medical waste incineration plant. Ambient air concentrations of polycyclic aromatic hydrocarbons (PAHs), PM₁₀ and PM_2.5 (PM—particulate matter) were determined by collecting air samples in areas both upwind and downwind of the plant. The differences in air pollutant levels between the study area and a reference area 11 km away from the plant were evaluated.Dichotomous samplers were used for sampling PM_2.5 and PM₁₀ from ambient air. Two hundred and twenty samples were obtained from the study area, and 100 samples were taken from a reference area. Samples were weighed by an electronic microbalance and concentrations of PM_2.5 and PM₁₀ were determined. A HPLC equipped with a fluorescence detector was employed to analyze the concentrations of 15 PAHs compounds adsorbed into PM_2.5 and PM₁₀.The experimental results indicated that the average concentrations of PM_2.5 and PM₁₀ were 30.34±17.95 and 36.81±20.45 μg m⁻³, respectively, in the study area, while the average ratio of PM_2.5/PM₁₀ was 0.82±0.01. The concentrations of PM_2.5 and PM₁₀ of the study area located downwind of the incinerator were significantly higher than the study area upwind of the incinerator (P<0.05).The concentration of PAHs in PM_2.5 in the study area was 2.2 times higher than in the reference area (P<0.05). Furthermore, the benzo(a)pyrene concentrations in PM_2.5 and PM₁₀ were 0.11±0.05 ng m⁻³ and 0.12±0.06 ng m⁻³ in the study area, respectively. The benzo(a)pyrene concentrations of PM_2.5 and PM₁₀ in the study area were 7 and 5.3 times higher than in the reference area (P<0.05), respectively.The study indicated that the air quality of PM_2.5, PM₁₀ and PAHs had significant contamination by air pollutants emitted from a medical waste incineration factory, representing a public health problem for nearby residences, despite the factory being equipped with a modern air pollution control system.     

Potential effects of particulate matter from combustion during services on human health and on works of art in medieval churches in Cyprus

Indoor and outdoor particulate matter (PM_0.3-10) number concentrations were established in two medieval churches in Cyprus. In both churches incense was burnt occasionally during Mass. The highest indoor PM_0.5-1 concentrations compared with outdoors (10.7 times higher) were observed in the church that burning of candles indoors was allowed. Peak indoor black carbon concentration was 6.8 μg m⁻³ in the instances that incense was burning and 13.4 μg m⁻³ in the instances that the candles were burning (outdoor levels ranged between 0.6 and 1.3 μg m⁻³). From the water soluble inorganic components determined in PM₁₀, calcium prevailed in all samples indoors or outdoors, whilst high potassium concentration indoors were a clear marker of combustion. Indoor sources of PM were clearly identified and their emission strengths were estimated via modeling of the results. Indoor estimated PM_0.3-10 mass concentrations exceeded air quality standards for human health protection and for the preservation of works of art.     

Characterization of Particulate Matter in California

ABSTRACT

The size, composition, and concentration of particulate matter (PM) vary with location and time. Several monitoring/sampling programs are operated in California to characterize PM less than 2.5 and 10 µm in aerodynamic diameter (PM_2.5 and PM₁₀). This paper presents a broad summary of the spatial and temporal variations observed in ambient PM_2.5 and PM₁₀ concentrations in California. Many areas that have high PM₁₀ concentrations also have relatively high PM_2.5 concentrations, and data indicate that a significant portion of the PM₁₀ air quality problem is caused by PM_2.5. To develop effective plans for attaining the ambient PM standards, improved understanding of these unique problems is needed. Since 1989, pollution control efforts—whether specifically targeted for particulate matter or indirectly via controls on gaseous emissions—have caused annual average PM_2.5 and PM₁₀ concentrations to decline at most sites in California.     

Evaluation of PM10 forecasting based on the artificial neural network model and intake fraction in an urban area: A case study in Taiyuan City,China

Primary fine particulate matters with a diameter of less than 10 µm (PM₁₀) are important air emissions causing human health damage. PM₁₀ concentration forecast is important and necessary to perform in order to assess the impact of air on the health of living beings. To better understand the PM₁₀ pollution health risk in Taiyuan City, China, this paper forecasted the temporal and spatial distribution of PM₁₀ yearly average concentration, using Back Propagation Artificial Neural Network (BPANN) model with various air quality parameters. The predicted results of the models were consistent with the observations with a correlation coefficient of 0.72. The PM₁₀ yearly average concentrations combined with the population data from 2002 to 2008 were given into the Intake Fraction (IF) model to calculate the IFs, which are defined as the integrated incremental intake of a pollutant released from a source category or a region over all exposed individuals. The results in this study are only for main stationary sources of the research area, and the traffic sources have not been included. The computed IFs results are therefore under-estimations. The IFs of PM₁₀ from Taiyuan with a mean of 8.5 per million were relatively high compared with other IFs of the United States, Northern Europe and other cities in China. The results of this study indicate that the artificial neural network is an effective method for PM₁₀ pollution modeling, and the Intake Fraction model provides a rapid population risk estimate for pollutant emission reduction strategies and policies.

Implications The PM₁₀ (particulate matter with an aerodynamic diameter ≤10 μm) yearly average concentration of Taiyuan, with a mean of 0.176 mg/m³, was higher than the 65 μg/m³ recommended by the U.S. Environmental Protection Agency (EPA). The spatial distribution of PM₁₀ yearly average concentrations showed that wind direction and wind speed played an important role, whereas temperature and humidity had a lower effect than expected. Intake fraction estimates of Taiyuan were relatively high compared with those observed in other cities. Population density was the major factor influencing PM₁₀ spatial distribution. The results indicated that the artificial neural network was an effective method for PM₁₀ pollution modeling.     

Installation of platform screen doors and their impact on indoor air quality: Seoul subway trains

In this study, variations of particulate matter (PM) concentrations in subway trains following installation of platform screen doors (PSDs) in the Seoul subway system were investigated. PM samples were collected in the trains on subway lines 1–8 before and after installation of PSDs. It was found that the mean PM₁₀ concentration in the trains after PSDs installation increased significantly by 29.9% compared to that before installation. In particular, the increase of PM₁₀ in line 6 was the highest at 103%. When the relationship between PM₁₀ and PM_2.5 was compared, coefficients of determination (r²) before and after PSDs installations were 0.696 and 0.169, respectively. This suggests that air mixing between the platform and the tunnel after PSDs installation was extremely restricted. In addition, the indoor/outdoor PM₁₀ ratio following PSDs installation increased from 1.32 to 2.97 relative to the period with no installed PSDs. Furthermore, this study revealed that PM levels in subway trains increased significantly after all underground PSDs were put in use. Several potential factors were examined that could result in this PM increase, such as train ventilation systems, operational conditions, passenger volume, subway depth, and the length of underground segments.

ImplicationsPM₁₀ concentrations inside the subway trains increased after PSDs installation. This indicates that air quality in trains was very seriously impacted by PSDs. PM₁₀ levels were also influenced by the tunnel depth and length of the underground segments. To prevent the adverse effect on human health by PM₁₀ emitted from the tunnel, an applicable ventilation system to reduce PM₁₀ is required inside trains and tunnels.     

Temporal variations of fine and coarse particulate matter sources in Jeddah,Saudi Arabia

This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM_2.5) and coarse (aerodynamic diameter 2.5–10 μm; PM_2.5–10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM_2.5 (21.9 μg/m³) and PM₁₀ (107.8 μg/m³) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM_2.5 (10 μg/m³) and PM₁₀ (20 μg/m³), respectively. Similar to other Middle Eastern locales, PM_2.5–10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM₁₀ mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM_2.5 and PM_2.5–10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM_2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM_2.5 (27%) and PM_2.5–10 (77%) mass, and the largest source contributor for PM_2.5 was from residual oil burning (63%). Temporal variations of PM_2.5–10 and PM_2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM_2.5 and PM_2.5–10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting.

Implications: Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM_2.5–10 is natural windblown soil and road dust, whereas the predominant source of PM_2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.     

PM2.5 and PM10: The influence of sugarcane burning on potential cancer risk

In Brazil, sugarcane fields are often burned to facilitate manual harvesting, and this burning causes environmental pollution from the large amounts of soot released into the atmosphere. This material contains numerous organic compounds such as PAHs. In this study, the concentrations of PAHs in two particulate-matter fractions (PM_2.5 and PM₁₀) in the city of Araraquara (SE Brazil, with around 200,000 inhabitants and surrounded by sugarcane plantations) were determined during the sugarcane harvest (HV) and non-harvest (NHV) seasons in 2008 and 2009. The sampling strategy included four campaigns, with 60 samples in the NHV season and 220 samples in the HV season. The PM_2.5 and PM₁₀ fractions were collected using a dichotomous sampler (10 L min^?1, 24 h) with Teflon? filters. The filter sets were extracted (ultrasonic bath with hexane/acetone (1:1 v/v)) and analyzed by HPLC/Fluorescence. The median concentration for total PAHs (PM_2.5 in 2009) was 0.99 ng m^?3 (NHV) and 3.3 ng m^?3 (HV). In the HV season, the total concentration of carcinogenic PAHs (benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene) was 5 times higher than in the NHV season. B(a)P median concentrations were 0.017 ng m^?3 and 0.12 ng m^?3 for the NHV and HV seasons, respectively. The potential cancer risk associated with exposure through inhalation of these compounds was estimated based on the benzo[a]pyrene toxic equivalence (BaP_eq), where the overall toxicity of a PAH mixture is defined by the concentration of each compound multiplied by its relative toxic equivalence factor (TEF). BaP_eq median (2008 and 2009 years) ranged between 0.65 and 1.0 ng m^?3 and 1.2–1.4 ng m^?3 for the NHV and HV seasons, respectively. Considering that the maximum permissible BaP_eq in ambient air is 1 ng m^?3, related to the increased carcinogenic risk, our data suggest that the level of human exposure to PAHs in cities surrounded by sugarcane crops where the burning process is used is cause for concern.     

PM10 source apportionment in a Swiss Alpine valley impacted by highway traffic

Although trans-Alpine highway traffic exhaust is one of the major sources of air pollution along the highway valleys of the Alpine regions, little is known about its contribution to residential exposure and impact on respiratory health. In this paper, source-specific contributions to particulate matter with an aerodynamic diameter?<?10 μm (PM₁₀) and their spatio-temporal distribution were determined for later use in a pediatric asthma panel study in an Alpine village. PM₁₀ sources were identified by positive matrix factorization using chemical trace elements, elemental, and organic carbon from daily PM₁₀ filters collected between November 2007 and June 2009 at seven locations within the village. Of the nine sources identified, four were directly road traffic-related: traffic exhaust, road dust, tire and brake wear, and road salt contributing 16 %, 8 %, 1 %, and 2 % to annual PM₁₀ concentrations, respectively. They showed a clear dependence with distance to highway. Additional contributions were identified from secondary particles (27 %), biomass burning (18 %), railway (11 %), and mineral dust including a local construction site (13 %). Comparing these source contributions with known source-specific biomarkers (e.g., levoglucosan, nitro-polycyclic aromatic hydrocarbons) showed high agreement with biomass burning, moderate with secondary particles (in winter), and lowest agreement with traffic exhaust.     

Demolition of High-Rise Public Housing Increases Particulate Matter Air Pollution in Communities of High-Risk Asthmatics

Abstract

Public housing developments across the United States are being demolished, potentially increasing local concentrations of particulate matter (PM) in communities with high burdens of severe asthma. Little is known about the impact of demolition on local air quality. At three public housing developments in Chicago, IL, PM with an aerodynamic diameter <10 μm (PM₁₀) and <2.5 μm were measured before and during high-rise demolition. Additionally, size-selective sampling and real-time monitoring were concurrently performed upwind and downwind of one demolition site. The concentration of particulates attributable to demolition was estimated after accounting for background urban air pollution. Particle microscopy was performed on a small number of samples. Substantial increases of PM₁₀ occurred during demolition, with the magnitude of that increase varying based on sampler distance, wind direction, and averaging time. During structural demolition, local concentrations of PM₁₀ 42 m downwind of a demolition site increased 4- to 9-fold above upwind concentrations (6-hr averaging time). After adjusting for background PM₁₀, the presence of dusty conditions was associated with a 74% increase in PM₁₀ 100 m downwind of demolition sites (24-hr averaging times). During structural demolition, short-term peaks in real-time PM₁₀ (30-sec averaging time) occasionally exceeded 500 μg/m³. The median particle size downwind of a demolition site (17.3 μm) was significantly larger than background (3 μm). Specific activities are associated with real-time particulate measures. Microscopy did not identify asbestos or high concentrations of mold spores. In conclusion, individuals living near sites of public housing demolition are at risk for exposure to high particulate concentrations. This increase is characterized by relatively large particles and high short-term peaks in PM concentration.     

Investigation of PM2.5 and carbon dioxide levels in urban homes

PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) samples were collected in the indoor environments of 15 urban homes and their adjacent outdoor environments in Alexandria, Egypt, during the spring time. Indoor and outdoor carbon dioxide (CO₂) levels were also measured concurrently. The results showed that indoor and outdoor PM_2.5 concentrations in the 15 sites, with daily averages of 45.5 ± 11.1 and 47.3 ± 12.9 µg/m³, respectively, were significantly higher than the ambient 24-hr PM_2.5 standard of 35 µg/m³ recommended by the U.S. Environmental Protection Agency (EPA). The indoor PM_2.5 and CO₂ levels were correlated with the corresponding outdoor levels, demonstrating that outdoor convection and infiltration could lead to direct transportation indoors. Ventilation rates were also measured in the selected residences and ranged from 1.6 to 4.5 hr^?1 with median value of 3.3 hr^?1. The indoor/outdoor (I/O) ratios of the monitored homes varied from 0.73 to 1.65 with average value of 0.99 ± 0.26 for PM_2.5, whereas those for CO₂ ranged from 1.13 to 1.66 with average value of 1.41 ± 0.15. Indoor sources and personal activities, including smoking and cooking, were found to significantly influence indoor levels.

Implications: Few studies on indoor air quality were carried out in Egypt, and the scarce data resulted from such studies do not allow accurate assessment of the current situation to take necessary preventive actions. The current research investigates indoor levels of PM_2.5 and CO₂ in a number of homes located in the city of Alexandria as well as the potential contribution from both indoor and outdoor sources. The study draws attention of policymakers to the importance of the establishment of national indoor air quality standards to protect human health and control air pollution in different indoor environments.     

Aerosol transport model evaluation of an extreme smoke episode in Southeast Asia

Biomass burning is one of many sources of particulate pollution in Southeast Asia, but its irregular spatial and temporal patterns mean that large episodes can cause acute air quality problems in urban areas. Fires in Sumatra and Borneo during September and October 2006 contributed to 24-h mean PM₁₀ concentrations above 150 μg m^?3 at multiple locations in Singapore and Malaysia over several days. We use the FLAMBE model of biomass burning emissions and the NAAPS model of aerosol transport and evolution to simulate these events, and compare our simulation results to 24-h average PM₁₀ measurements from 54 stations in Singapore and Malaysia. The model simulation, including the FLAMBE smoke source as well as dust, sulfate, and sea salt aerosol species, was able to explain 50% or more of the variance in 24-h PM₁₀ observations at 29 of 54 sites. Simulation results indicated that biomass burning smoke contributed to nearly all of the extreme PM₁₀ observations during September–November 2006, but the exact contribution of smoke was unclear because the model severely underestimated total smoke emissions. Using regression analysis at each site, the bias in the smoke aerosol flux was determined to be a factor of between 2.5 and 10, and an overall factor of 3.5 was estimated. After application of this factor, the simulated smoke aerosol concentration averaged 20% of observed PM₁₀, and 40% of PM₁₀ for days with 24-h average concentrations above 150 μg m^?3. These results suggest that aerosol transport models can aid analysis of severe pollution events in Southeast Asia, but that improvements are needed in models of biomass burning smoke emissions.     

Prescribed Burns and Wildfires in Colorado: Impacts of Mitigation Measures on Indoor Air Particulate Matter

Abstract

Wildfires and prescribed burns are receiving increasing attention as sources of fine particulate matter (PM_2.5). The goal of this research project was to understand the impact of mitigation strategies for residences impacted by scheduled prescribed burns and wildfires. Pairs of residences were solicited to have PM_2.5 concentrations monitored inside and outside of their houses during four fires. The effect of using air cleaners on indoor PM_2.5 was investigated, as well as the effect of keeping windows closed. Appropriately sized air cleaners were provided to one of each pair of residences; occupants of all of the residences were asked to keep windows shut and minimize opening of exterior doors. Additionally, residents were asked to record all of the activities that may be a source of particulate matter, such as cooking and cleaning. Measurements were made during one prescribed burn and three wildfires during the 2002 fire season. Outdoor 24‐hr average PM_2.5 concentrations ranging from 6 to 38 µg/m³ were measured during the fires, compared with levels of 2–5 µg/m³ during background measurements when no fires were burning. During the fires, PM_2.5 was <3 µg/m³ inside all of the houses with air cleaners installed. This corresponds with a decrease of 63–88% in homes with the air cleaners operating when compared with homes without air cleaners. In the homes without the air cleaners, measured indoor concentrations were 58–100% of the concentrations measured outdoors.     

PAH air pollution at a Portuguese urban area: carcinogenic risks and sources identification

This study aimed to characterize air pollution and the associated carcinogenic risks of polycyclic aromatic hydrocarbon (PAHs) at an urban site, to identify possible emission sources of PAHs using several statistical methodologies, and to analyze the influence of other air pollutants and meteorological variables on PAH concentrations.The air quality and meteorological data were collected in Oporto, the second largest city of Portugal. Eighteen PAHs (the 16 PAHs considered by United States Environment Protection Agency (USEPA) as priority pollutants, dibenzo[a,l]pyrene, and benzo[j]fluoranthene) were collected daily for 24 h in air (gas phase and in particles) during 40 consecutive days in November and December 2008 by constant low-flow samplers and using polytetrafluoroethylene (PTFE) membrane filters for particulate (PM₁₀ and PM_2.5 bound) PAHs and pre-cleaned polyurethane foam plugs for gaseous compounds. The other monitored air pollutants were SO₂, PM₁₀, NO₂, CO, and O₃; the meteorological variables were temperature, relative humidity, wind speed, total precipitation, and solar radiation. Benzo[a]pyrene reached a mean concentration of 2.02 ng?m^?3, surpassing the EU annual limit value. The target carcinogenic risks were equal than the health-based guideline level set by USEPA (10^?6) at the studied site, with the cancer risks of eight PAHs reaching senior levels of 9.98?×?10^?7 in PM₁₀ and 1.06?×?10^?6 in air. The applied statistical methods, correlation matrix, cluster analysis, and principal component analysis, were in agreement in the grouping of the PAHs. The groups were formed according to their chemical structure (number of rings), phase distribution, and emission sources. PAH diagnostic ratios were also calculated to evaluate the main emission sources. Diesel vehicular emissions were the major source of PAHs at the studied site. Besides that source, emissions from residential heating and oil refinery were identified to contribute to PAH levels at the respective area. Additionally, principal component regression indicated that SO₂, NO₂, PM₁₀, CO, and solar radiation had positive correlation with PAHs concentrations, while O₃, temperature, relative humidity, and wind speed were negatively correlated.     

The impact of wood stove technology upgrades on indoor residential air quality

Fine particulate matter (PM_2.5) air pollution has been linked to adverse health impacts, and combustion sources including residential wood-burning may play an important role in some regions. Recent evidence suggests that indoor air quality may improve in homes where older, non-certified wood stoves are exchanged for lower emissions EPA-certified alternatives. As part of a wood stove exchange program in northern British Columbia, Canada, we sampled outdoor and indoor air at 15 homes during 6-day sampling sessions both before and after non-certified wood stoves were exchanged. During each sampling session two consecutive 3-day PM_2.5 samples were collected onto Teflon filters, which were weighed and analyzed for the wood smoke tracer levoglucosan. Residential PM_2.5 infiltration efficiencies (F_inf) were estimated from continuous light scattering measurements made with nephelometers, and estimates of F_inf were used to calculate the outdoor- and indoor-generated contributions to indoor air. There was not a consistent relationship between stove technology and outdoor or indoor concentrations of PM_2.5 or levoglucosan. Mean F_inf estimates were low and similar during pre- and post-exchange periods (0.32 ± 0.17 and 0.33 ± 0.17, respectively). Indoor sources contributed the majority (～65%) of the indoor PM_2.5 concentrations, independent of stove technology, although low indoor-outdoor levoglucosan ratios (median ≤ 0.19) and low indoor PM_2.5-levoglucosan correlations (r ≤ 0.19) suggested that wood smoke was not a major indoor PM_2.5 source in most of these homes. In summary, despite the potential for extensive wood stove exchange programs to reduce outdoor PM_2.5 concentrations in wood smoke-impacted communities, we did not find a consistent relationship between stove technology upgrades and indoor air quality improvements in homes where stoves were exchanged.     

Indoor particle size distributions in homes with open fires and improved Patsari cook stoves

Particulate pollution has been clearly linked with adverse health impacts from open fire cookstoves, and indoor air concentrations are frequently used as a proxy for exposures in health studies. Implicit are the assumptions that the size distributions for the open fire and improved stove are not significantly different, and that the relationship between indoor concentrations and personal exposures is the same between stoves. To evaluate the impact of these assumptions size distributions of particulate matter in indoor air were measured with the Sioutas cascade impactor in homes using open fires and improved Patsari stoves in a rural Purepecha community in Michoacan, Mexico. On average indoor concentrations of particles less than 0.25 μm were 72% reduced in homes with improved Patsari stoves, reflecting a reduced contribution of this size fraction to PM_2.5 mass concentrations from 68% to 48%. As a result the mass median diameter of indoor PM_2.5 particulate matter was increased by 29% with the Patsari improved stove compared to the open fire (from 0.42 μm to 0.59 μm, respectively). Personal PM_2.5 exposure concentrations for women in homes using open fires were approximately 61% of indoor concentration levels (156 μg m^?3 and 257 μg m^?3 respectively). In contrast personal exposure concentrations were 77% times indoor air concentration levels for women in homes using improved Patsari stoves (78 μg m^?3and 101 μg m^?3 respectively). Thus, if indoor air concentrations are used in health and epidemiologic studies significant bias may result if the shift in size distribution and the change in relationship between indoor air concentrations and personal exposure concentrations are not accounted for between different stove types.     

Characterizing and predicting coarse and fine particulates in classrooms located close to an urban roadway

The PM₁₀, PM_2.5, and PM₁ (particulate matter with aerodynamic diameters <10, <2.5, and <1 μm, respectively) concentrations were monitored over a 90-day period in a naturally ventilated school building located at roadside in Chennai City. The 24-hr average PM₁₀, PM_2.5, and PM₁ concentrations at indoor and outdoor environments were found to be 136 ± 60, 36 ± 15, and 20 ± 12 and 76 ± 42, 33 ± 16, and 23 ± 14 μg/m³, respectively. The size distribution of PM in the classroom indicated that coarse mode was dominant during working hours (08:00 a.m. to 04:00 p.m.), whereas fine mode was dominant during nonworking hours (04:00 p.m. to 08:00 a.m.). The increase in coarser particles coincided with occupant activities in the classrooms and finer particles were correlated with outdoor traffic. Analysis of indoor PM₁₀, PM_2.5, and PM₁ concentrations monitored at another school, which is located at urban reserved forest area (background site) indicated 3–4 times lower PM₁₀ concentration than the school located at roadside. Also, the indoor PM₁ and PM_2.5 concentrations were 1.3–1.5 times lower at background site. Further, a mass balance indoor air quality (IAQ) model was modified to predict the indoor PM concentration in the classroom. Results indicated good agreement between the predicted and measured indoor PM_2.5 (R² = 0.72–0.81) and PM₁ (R² = 0.81–0.87) concentrations. But, the measured and predicted PM₁₀ concentrations showed poor correlation (R² = 0.17–0.23), which may be because the IAQ model could not take into account the sudden increase in PM₁₀ concentration (resuspension of large size particles) due to human activities.

Implications:The present study discusses characteristics of the indoor coarse and fine PM concentrations of a naturally ventilated school building located close to an urban roadway and at a background site in Chennai City, India. The study results will be useful to engineers and policymakers to prepare strategies for improving the IAQ inside classrooms. Further, this study may help in the development of IAQ standards and guidelines in India.