Elevated Particulate Matter Research Articles

Quantifying the contribution of long-range transport to particulate matter (PM) mass loadings at a suburban site in the north-western Indo-Gangetic Plain (NW-IGP)

Abstract. Many sites in the densely populated Indo-Gangetic Plain (IGP) frequently exceed the national ambient air quality standard (NAAQS) of 100 μg m−3 for 24 h average PM10 and 60 μg m−3 for 24 h average PM2.5 mass loadings, exposing residents to hazardous levels of particulate matter (PM) throughout the year. We quantify the contribution of long-range transport to elevated PM levels and the number of exceedance events through a back-trajectory climatology analysis of air masses arriving at the IISER Mohali Atmospheric Chemistry facility (30.667° N, 76.729° E; 310 m a.m.s.l.) for the period August 2011–June 2013. Air masses arriving at the receptor site were classified into six clusters, which represent synoptic-scale air-mass transport patterns. Long-range transport from the west leads to significant enhancements in the average fine- and coarse-mode PM mass loadings during all seasons. The contribution of long-range transport from the west and south-west (source regions: Arabia, Thar Desert, Middle East and Afghanistan) to coarse-mode PM varied between 9 and 57 % of the total PM10–2.5 mass. Local pollution episodes (wind speed < 1 m s−1) contributed to enhanced PM2.5 mass loadings during both the winter and summer seasons and to enhanced coarse-mode PM only during the winter season. South-easterly air masses (source region: eastern IGP) were associated with significantly lower fine- and coarse-mode PM mass loadings during all seasons. The fraction of days in each season during which the PM mass loadings exceeded the national ambient air quality standard was controlled by long-range transport to a much lesser degree. For the local cluster, which represents regional air masses (source region: NW-IGP), the fraction of days during which the national ambient air quality standard (NAAQS) of 60 μg m−3 for 24 h average PM2.5 was exceeded varied between 36 % of the days associated with this synoptic-scale transport during the monsoon, and 95 % during post-monsoon and winter seasons; the fraction of days during which the NAAQS of 100 μg m−3 for the 24 h average PM10 was exceeded, varied between 48 % during the monsoon and 98 % during the post-monsoon season. Long-range transport was responsible for both, bringing air masses with a significantly lower fraction of exceedance days from the eastern IGP and air masses with a moderate increase in the fraction of exceedance days from the west (source regions: Arabia, Thar Desert, Middle East and Afghanistan). In order to bring PM mass loadings into compliance with the NAAQS and to reduce the number of exceedance days, mitigation of regional combustion sources in the NW-IGP needs to be given highest priority.

Source sector and region contributions to BC and PM<sub>2.5</sub> in Central Asia

Abstract. Particulate matter (PM) mass concentrations, seasonal cycles, source sector, and source region contributions in Central Asia (CA) are analyzed for the period April 2008–July 2009 using the Sulfur Transport and dEposition Model (STEM) chemical transport model and modeled meteorology from the Weather Research and Forecasting (WRF) model. Predicted aerosol optical depth (AOD) values (annual mean value ~0.2) in CA vary seasonally, with lowest values in the winter. Surface PM2.5 concentrations (annual mean value ~10 μg m−3) also exhibit a seasonal cycle, with peak values and largest variability in the spring/summer, and lowest values and variability in the winter (hourly values from 2 to 90 μg m−3). Surface concentrations of black carbon (BC) (mean value ~0.1 μg m−3) show peak values in the winter. The simulated values are compared to surface measurements of AOD as well as PM2.5, PM10, BC, and organic carbon (OC) mass concentrations at two regional sites in Kyrgyzstan (Lidar Station Teplokluchenka (LST) and Bishkek). The predicted values of AOD and PM mass concentrations and their seasonal cycles are fairly well captured. The carbonaceous aerosols are underpredicted in winter, and analysis suggests that the winter heating emissions are underestimated in the current inventory. Dust, from sources within and outside CA, is a significant component of the PM mass and drives the seasonal cycles of PM and AOD. On an annual basis, the power and industrial sectors are found to be the most important contributors to the anthropogenic portion of PM2.5. Residential combustion and transportation are shown to be the most important sectors for BC. Biomass burning within and outside the region also contributes to elevated PM and BC concentrations. The analysis of the transport pathways and the variations in particulate matter mass and composition in CA demonstrates that this region is strategically located to characterize regional and intercontinental transport of pollutants. Aerosols at these sites are shown to reflect dust, biomass burning, and anthropogenic sources from Europe; South, East, and Central Asia; and Russia depending on the time period. Simulations for a reference 2030 emission scenario based on pollution abatement measures already committed to in current legislation show that PM2.5 and BC concentrations in the region increase, with BC growing more than PM2.5 on a relative basis. This suggests that both the health impacts and the climate warming associated with these particles may increase over the next decades unless additional control measures are taken. The importance of observations in CA to help characterize the changes that are rapidly taking place in the region are discussed.

Mass concentrations and indoor-outdoor relationships of PM in selected educational buildings in Nis, Serbia

Mass concentrations of particulate matter (PM) fractions were measured in educational buildings in the city of Nis, Republic of Serbia. Two sampling campaigns were conducted in winter periods. The first campaign was in the period from 21 February to 15 April 2010 at the Faculty of Occupational Safety (FOS) and the second campaign was from 20 March to 4 April 2013 at the primary school Vozd Karadjordje (VK). PM measurements were carried out with low volume samplers Sven/Leckel LVS3. The average daily PM10 concentration inside the FOS (47.0 ?21.8 ?g/m3) was lower than PM10 concentration in outdoor air (50.7 ?28.1 ?g/m3). The average daily PM10 concentration inside the VK (54.6 ? 17.6 ?g/m3) was higher than in outdoor air (47.9 ? 22.8 ?g/m3). The 24 hours average PM10 concentrations at FOS exceeded the EU limit value (50 mg/m3) during 34 % of days outdoors, and 39 % of days indoors. The 24 hours average PM10 concentrations at VK exceeded the limit value during 35 % of days outdoors, and 53 % of days indoors. The 24 hours average PM2.5 concentrations at VK exceeded the WHO daily mean guideline value (25 mg/m3) during 71 % of days outdoors, and 88 % of days indoors. The average PM10 I/O ratio at VK was 1.57 during teaching hours, and 1.00 during no teaching hours. Similarly, average PM2.5 I/O ratio at VK was 1.11 during teaching hours and 0.90 during no teaching hours. Average daily PM2.5/PM10 ratio in the ambient air at VK was 0.87, and 0.82 at FOS. Very strong correlations between the indoor and outdoor PM concentrations were observed at VK during no teaching hours (r>0.8). Moderate to strong negative correlations were found between the wind speed and PM at both schools. High outdoor PM concentrations and resuspension of particles are probably the most possible reasons for the elevated indoor PM concentrations found in the study.

Characterizing airborne fungal and bacterial concentrations and emission rates in six occupied children's classrooms.

Baseline information on size-resolved bacterial, fungal, and particulate matter (PM) indoor air concentrations and emission rates is presented for six school classrooms sampled in four countries. Human occupancy resulted in significantly elevated airborne bacterial (81 times on average), fungal (15 times), and PM mass (nine times) concentrations as compared to vacant conditions. Occupied indoor/outdoor (I/O) ratios consistently exceeded vacant I/O ratios. Regarding size distributions, average room-occupied bacterial, fungal, and PM geometric mean particle sizes were similar to one another while geometric means estimated for bacteria, fungi, and PM mass during vacant sampling were consistently lower than when occupied. Occupancy also resulted in elevated indoor bacterial-to-PM mass-based and number-based ratios above corresponding outdoor levels. Mean emission rates due to human occupancy were 14 million cells/person/h for bacteria, 14 million spore equivalents/person/h for fungi, and 22 mg/person/h for PM mass. Across all locations, indoor emissions contributed 83 ± 27% (bacteria), 66 ± 19% (fungi), and 83 ± 24% (PM mass) of the average indoor air concentrations during occupied times. An extensive data set of bacterial and fungal size-distributed indoor air concentrations and emission rates is presented. Analysis of these data contributes to an understanding of how indoor bacterial and fungal aerosols are influenced by human occupancy. This work extends beyond prior culture and DNA-based microbiome studies in buildings to include quantitative relationships between size-resolved bacterial and fungal concentrations in indoor air and building parameters such as occupancy, ventilation, and outdoor conditions. The work indicates that occupancy-associated emissions (e.g., via resuspension and shedding) contribute more to both bacterial and fungal indoor air concentrations than do outdoor sources for the occupied classrooms investigated in this study.

Two-stroke scooters are a dominant source of air pollution in many cities.

Fossil fuel-powered vehicles emit significant particulate matter, for example, black carbon and primary organic aerosol, and produce secondary organic aerosol. Here we quantify secondary organic aerosol production from two-stroke scooters. Cars and trucks, particularly diesel vehicles, are thought to be the main vehicular pollution sources. This needs re-thinking, as we show that elevated particulate matter levels can be a consequence of 'asymmetric pollution' from two-stroke scooters, vehicles that constitute a small fraction of the fleet, but can dominate urban vehicular pollution through organic aerosol and aromatic emission factors up to thousands of times higher than from other vehicle classes. Further, we demonstrate that oxidation processes producing secondary organic aerosol from vehicle exhaust also form potentially toxic 'reactive oxygen species'.

Investigation of time-resolved atmospheric conditions and indoor/outdoor particulate matter concentrations in homes with gas and biomass cook stoves in Nogales, Sonora, Mexico

This paper reports findings from a case study designed to investigate indoor and outdoor air quality in homes near the United States–Mexico border. During the field study, size-resolved continuous particulate matter (PM) concentrations were measured in six homes, while outdoor PM was simultaneously monitored at the same location in Nogales, Sonora, Mexico, during March 14–30, 2009. The purpose of the experiment was to compare PM in homes using different fuels for cooking, gas versus biomass, and to obtain a spatial distribution of outdoor PM in a region where local sources vary significantly (e.g., highway, border crossing, unpaved roads, industry). Continuous PM data were collected every 6 seconds using a valve switching system to sample indoor and outdoor air at each home location. This paper presents the indoor PM data from each home, including the relationship between indoor and outdoor PM. The meteorological conditions associated with elevated ambient PM events in the region are also discussed. Results indicate that indoor air pollution has a strong dependence on cooking fuel, with gas stoves having hourly averaged median PM3 concentrations in the range of 134 to 157 μg m−3 and biomass stoves 163 to 504 μg m−3. Outdoor PM also indicates a large spatial heterogeneity due to the presence of microscale sources and meteorological influences (median PM3: 130 to 770 μg m−3). The former is evident in the median and range of daytime PM values (median PM3: 250 μg m−3, maximum: 9411 μg m−3), while the meteorological influences appear to be dominant during nighttime periods (median PM3: 251 μg m−3, maximum: 10,846 μg m−3). The atmospheric stability is quantified for three nighttime temperature inversion episodes, which were associated with an order of magnitude increase in PM10 at the regulatory monitor in Nogales, AZ (maximum increase: 12 to 474 μg m−3).Implications:Regulatory air quality standards are based on outdoor ambient air measurements. However, a large fraction of time is typically spent indoors where a variety of activities including cooking, heating, tobacco smoking, and cleaning can lead to elevated PM concentrations. This study investigates the influence of meteorology, outdoor PM, and indoor activities on indoor air pollution (IAP) levels in the United States–Mexico border region. Results indicate that cooking fuel type and meteorology greatly influence the IAP in homes, with biomass fuel use causing the largest increase in PM concentration.

A Case Study of Landfill Workers Exposure and Dose to Particulate Matter-Bound Metals

The objective of the current study was to estimate the dose in human tissues after inhalation exposure to airborne particulate matter-bound metals at a landfill site. Field measurements have revealed that the 8-h permissible exposure limit set by the Occupational Safety and Health Administration for particulate matter (PM10) was not exceeded for the working personnel at an outdoor weighing facility in the Akrotiri landfill (Chania, Greece). However, PM10 concentrations were exceeding the EU health protection standards (50 μg/m3). Furthermore, dust emanating from landfill operations contains traces of heavy metals due to the nature of materials (e.g., sludge, batteries) which have been deposited over the lifetime of the landfill. In addition, particulate matter-bound metals concentrations at the landfill are enhanced by refuse truck emissions (e.g., exhaust, tire wear dust, brake wear dust, road surface wear dust and resuspension of deposited PM on a road surface) and resuspension from the surface of the composting site. Estimations of particle-bound metals dose in the human body were performed for arsenite (ASIII), lead (Pb) and cadmium (Cd). The Exposure Dose Model (ExDoM) in conjunction with a Physiologically Based PharmacoKinetic (PBPK) model was applied to determine the dose for an adult Caucasian male worker. The ExDoM was used to estimate the human exposure and the deposition, dose, clearance, retention of particulate matter-bound metals in the human respiratory tract and the mass transferred to the gastrointestinal tract and blood. The PBPK model was developed to describe the movement of metals from the blood into the tissues as a blood-flow-limited model. The results showed that after 1 day of exposure to PMAsIII, the major accumulation occurs in the lung, muscle and liver. In addition, for PMPb, the major accumulation occurs in the bone, blood and muscle whereas as regard PMCd the major accumulation occurs in the other tissues (the rest of the body), kidney and liver. The results indicate an increased health risk for an adult Caucasian male worker at the landfill site due to exposure to elevated particulate matter concentrations and their associated metallic content.

Quantifying the Contribution of Long-Range Saharan Dust Transport on Particulate Matter Concentrations in Houston, Texas, Using Detailed Elemental Analysis

The trans-Atlantic transport of North African dust by summertime trade winds occasionally increases ambient particulate matter (PM) concentrations in Texas above air quality standards. Exemptions from such exceedences can be sought for episodic events that are beyond regulatory control by providing qualitative supportive information such as satellite images and back-trajectories. Herein we demonstrate that chemical mass balancing can successfully isolate, differentiate, and quantify the relative contributions from local and global mineral dust sources through detailed measurements of a wide suite of elements in ambient PM. We identified a major dust storm originating in Northwest Africa in mid-July 2008 which eventually impacted air quality in Houston during July 25, 26, and 27, 2008. Daily PM2.5 and PM10 samples were collected at two sites in Houston over a 2-week period encompassing the Saharan dust episode to quantify the transported mineral dust concentrations during this peak event. Average PM concentrations more than doubled during the Saharan intrusion compared with non-Saharan. Relative concentrations of several elements often associated with anthropogenic sources were significantly diluted by crustal minerals coincident with the large-scale Saharan dust intrusion. During non-Saharan days, local mineral dust sources including cement manufacturing and soil and road dust contributed in total 26% to PM2.5 mass and 50% to PM10 mass; during the three-day Saharan episode the total dust contribution increased to 64% for PM2.5 and 85% for PM10. Importantly, this approach was also able to determine that local emissions of crustal minerals dominated the period immediately following the Saharan dust episode: simple quantification of bulk crustal materials may have misappropriated this elevated PM to trans-Atlantic transport of Saharan dust.

Investigation of PM10 sources in Santa Catarina, Brazil through graphical interpretation analysis combined with receptor modelling

Epidemiological studies have documented that elevated airborne particulate matter (PM) concentrations, especially those with an aerodynamic diameter less than 10 μm (PM10), are associated with adverse health effects. Two receptor models, UNMIX and positive matrix factorization (PMF), were used to identify and quantify the sources of PM10 concentrations in Tubarão and Capivari de Baixo, Santa Catarina, Brazil. This region is known for its high pollution levels due to intense industrial activity and exploitation of natural resources. PM10 samples were collected using high volume samplers at two sites in the region and statistical exploratory analysis techniques were applied to identify and assess PM10 sources. The two primary PM10 sources were identified as soil re-suspension/road dust emissions and coal burning emissions, contributing 65–75% and 15–25% of the PM10, respectively. The study confirmed the significance of the influence of local PM10 emissions (power plants, soil re-suspension and road dust emissions) on regional air quality, although no violations of the Brazilian PM10 standards (limit of 150 μg/m3) were observed, with a mean concentration of 27.6 μg/m3 measured in this study. This study demonstrated the usefulness of statistical exploratory analysis techniques in assessing the validity of modelling results and contributing to the interpretation of ambient air quality data.

Influence of background particulate matter (PM) on urban air quality in the Pacific Northwest

Elevated particulate matter concentrations due to Asian long-range transport (LRT) are frequently observed in the free troposphere (FT) above the Pacific Northwest, U.S. Transport of this aerosol from the FT to the boundary layer (BL) and its effect to local air quality remain poorly constrained. We used data collected at the Mount Bachelor observatory (MBO, 2.8 km a.s.l) and from ground stations in the Pacific Northwest to study transport of fine particulate matter (PM) from the FT to the BL. During Asian LRT episodes PM concentrations were clearly elevated above the corresponding monthly averages at MBO as well as at low elevation sites across Washington and Oregon. Also, a clear correlation between MBO and low elevation sites was observed, indicating that LRT episodes are seen in both the FT and BL. In addition, drum impactor measurements show that the chemical composition of PM at MBO was similar to that measured at the BL sites. Using a simple regression model, we estimate that during springtime, when the transport from Asia is most effective, the contribution of Asian sources to PM2.5 in clean background areas of the Pacific Northwest was on average 1.7 μg m−3 (representing approximately 50–80% of PM). The influence of LRT PM was also seen in measurement stations situated in the urban and urban background areas. However, the fraction of LRT PM was less pronounced (36–50% of PM) due to larger local emissions in the urban areas.

A systematic review of air pollution as a risk factor for cardiovascular disease in South Asia: Limited evidence from India and Pakistan

Cardiovascular diseases (CVD) are major contributors to mortality and morbidity in South Asia. Chronic exposure to air pollution is an important risk factor for cardiovascular diseases, although the majority of studies to date have been conducted in developed countries. Both indoor and outdoor air pollution are growing problems in developing countries in South Asia yet the impact on rising rates of CVD in these regions has largely been ignored. We aimed to assess the evidence available regarding air pollution effects on CVD and CVD risk factors in lower income countries in South Asia. A literature search was conducted in PubMed and Web of Science. Our inclusion criteria included peer-reviewed, original, empirical articles published in English between the years 1990 and 2012, conducted in the World Bank South Asia region (Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka). This resulted in 30 articles. Nine articles met our inclusion criteria and were assessed for this systematic review. Most of the studies were cross-sectional and examined measured particulate matter effects on CVD outcomes and indicators. We observed a bias as nearly all of the studies were from India. Hypertension and CVD deaths were positively associated with higher particulate matter levels. Biomarkers of oxidative stress such as increased levels of P-selection expressing platelets, depleted superoxide dismutase and reactive oxygen species generation as well as elevated levels of inflammatory-related C-reactive protein, interleukin-6 and interleukin-8 were also positively associated with biomass use or elevated particulate matter levels. An important outcome of this investigation was the evidence suggesting important air pollution effects regarding CVD risk in South Asia. However, too few studies have been conducted. There is as an urgent need for longer term investigations using robust measures of air pollution with different population groups that include a wider range of air pollutants and outcomes, including early indicators of CVD. These regions are facing burdens from increasing urbanization, air pollution and populations, generally weaker health infrastructure, aging populations and increased incidence of non-communicable diseases, included CVD. The extent to which the problem of air pollution and CVD will impact these countries will depend largely on the information available to inform policy and programs, which are still lacking, political will as well as social and economic development.

An evaluation of mass, number concentration, chemical composition and types of particles in a cafeteria before and after the passage of an antismoking law

This study assessed air quality indicators before and after enactment of the Spanish anti-smoking law. Mass and number concentrations and the chemical composition of particles were evaluated. Microscopy analyses were also conducted. Real time concentrations of PM10, PM2.5, PM1 and ultrafine particles were measured under ventilated and non-ventilated conditions and PM10 samples were collected for detailed inorganic and organic chemical characterization. Before enactment of the law in 2010, tobacco smoke produced significant indoor ambient particulate matter pollution, with elevated particulate matter mass concentrations (PM10 and PM1 concentrations of 122–220 and 48–85μg/m3, respectively) and ultrafine particle numbers (75,000 and 48,000cm–3 under ventilated and non-ventilated conditions, respectively). Typical tobacco smoke tracers including iso- and anteiso-alkanes and elements including La and Ce from the ignition of lighters were abundant. Additionally, several toxic substances derived from tobacco smoke, including Cd (3.1ng/m3) and benzo[a]pyrene (1.0ng/m3) were present at concentrations approximately 10 times greater than those measured after enactment of the anti-smoking law. The anti-smoking law significantly reduced exposure to potentially toxic compounds by approximately 90%. This law is expected to have a positive health impact, particularly for people who spend considerable time in affected environments, such as employees.

Air quality modelling using the Met Office Unified Model (AQUM OS24-26): model description and initial evaluation

Abstract. The on-line air quality model AQUM (Air Quality in the Unified Model) is a limited-area forecast configuration of the Met Office Unified Model which uses the UKCA (UK Chemistry and Aerosols) sub-model. AQUM has been developed with two aims: as an operational system to deliver regional air quality forecasts and as a modelling system to conduct air quality studies to inform policy decisions on emissions controls. This paper presents a description of the model and the methods used to evaluate the performance of the forecast system against the automated UK surface network of air quality monitors. Results are presented of evaluation studies conducted for a year-long period of operational forecast trials and several past cases of poor air quality episodes. The results demonstrate that AQUM tends to over-predict ozone (~8 μg m−3 mean bias for the year-long forecast), but has a good level of responsiveness to elevated ozone episode conditions – a characteristic which is essential for forecasting poor air quality episodes. AQUM is shown to have a negative bias for PM10, while for PM2.5 the negative bias is much smaller in magnitude. An analysis of speciated PM2.5 data during an episode of elevated particulate matter (PM) suggests that the PM bias occurs mainly in the coarse component. The sensitivity of model predictions to lateral boundary conditions (LBCs) has been assessed by using LBCs from two different global reanalyses and by comparing the standard, single-nested configuration with a configuration having an intermediate European nest. We conclude that, even with a much larger regional domain, the LBCs remain an important source of model error for relatively long-lived pollutants such as ozone. To place the model performance in context we compare AQUM ozone forecasts with those of another forecasting system, the MACC (Monitoring Atmospheric Composition and Climate) ensemble, for a 5-month period. An analysis of the variation of model skill with forecast lead time is presented and the insights this provides to the relative sources of error in air quality modelling are discussed.

Crop Productivity and Nutrient Dynamics in a Shrub (Guiera senegalensis)–Based Farming System of the Sahel

The indigenous shrub, Guiera senegalensis, coexists with crops to varying degrees in farmers' fields throughout the Sahel, with little known about its biophysical and ecological interactions with soils and crops. Therefore, the objectives were to determine the effect of the presence or absence of shrubs under varying rates of fertilizer on: (i) crop growth and yield, and (ii) soil nutrient dynamics. An experiment from 2004 to 2007 was conducted in northern Senegal where G. senegalensis dominates that had a split‐plot factorial design. The presence or absence of G. senegalensis was the main plot and fertilizer rate (0, 0.5, 1 or 1.5 times the recommended N–P–K rate) was the subplot in a peanut (Arachis hypogaea L.) –pearl millet [Pennisetum glaucum (L.) R. Br.] rotation. Averaging over fertilizer rate showed that G. senegalensis had significantly greater crop biomass and yields than no shrub plots (P < 0.05) for all 4 yr. This crop yield response was related to improved nutrient availability (significantly greater for crop N and P uptake in the presence than absence of shrubs in zero fertilizer plots), higher soil quality (elevated particulate organic matter (POM) with shrubs, and a significant correlation of POM with millet yield). Lysimeters below the crop rooting zone had inorganic N levels that were not significantly affected by shrubs compared to no shrub plots, which was attributed to high variability. Combining the ecological potential to restore degraded landscapes with the agronomic benefits demonstrated here, shows that optimized G. senegalensis–crop systems should be further investigated in farmers' fields throughout the Sahel.

Meteorological characteristics of dust storm events in the eastern Great Basin of Utah, U.S.A.

We assess the mesoscale climatology of dust storm events affecting Salt Lake City, Utah (SLC) since the 1930s, and document the ascendant controls on atmospheric dust generation and transport in the semi-arid Great Basin. Records indicate a seasonal and diurnal pattern, with dust storms typically occurring in spring months during the afternoon. Since 1930, SLC had 379 dust event days (DEDs), averaging 4.7 per year. Air quality station data from populated regions in Utah indicate that dust events produced elevated PM10 exceeding NAAQS on 16 days since 1993, or 0.9 per year. Analysis of DEDs over the period 1948–2010 (n = 331) indicates that approaching mid-level troughs caused 68% of these dust outbreaks and storms. We analyzed two significant DEDs occurring on 19 April 2008 and 4 March 2009, both of which produced elevated particulate matter (PM) levels in the populated region surrounding SLC. Strengthening cyclonic systems are the primary producer of dust outbreaks and storms; the Great Basin Confluence Zone (GBCZ) in the lee of the Sierra Nevada is a known region of cyclogenesis. These cyclonic systems produce strong southwesterly winds in the eastern Great Basin of Utah - termed “hatu winds” – that exceed threshold friction velocities, entrain sediments and loft them into the atmosphere. Plumes identified in MODIS satellite imagery on case study DEDs indicate specific dust source areas, not widespread sediment mobilization. These “hotspots” include playa surfaces at Sevier Dry Lake, Tule Dry Lake, and the Great Salt Lake Desert, as well as Milford Flat, an area burned by Utah's largest wildfire in 2007. The characteristic mountain-valley topography in the Basin & Range physiographic province creates terrain channeling that enhances deflation and funnels dust-bearing winds toward SLC, a growing urban center.

Anomalous elevated radiocarbon measurements of PM2.5

Two-component models are often used to determine the contributions made by fossil fuel and natural sources of carbon in airborne particulate matter (PM). The models reduce thousands of actual sources to two end members based on isotopic signature. Combustion of fossil fuels produces PM free of carbon-14 (14C). Wood or charcoal smoke, restaurant fryer emissions, and natural emissions from plants produce PM with the contemporary concentration of 14C approximately 1.2×10−1214C/C. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading and radiocarbon analysis is becoming a popular source apportionment method. Emissions from incinerators combusting medical or biological wastes containing tracer 14C can skew the 14C/C ratio of PM, however, so critical analysis of sampling sites for possible sources of elevated PM needs to be completed prior to embarking on sampling campaigns. Results are presented for two ambient monitoring sites in different areas of the United States where 14C contamination is apparent. Our experience suggests that such contamination is uncommon but is also not rare (∼10%) for PM sampling sites.

The Relationship Between Indoor Particulate Matter and Home Ventilation

Indoor particulate matter (PM) concentrations have been shown to correlate with increased asthma symptoms, while poor home ventilation has been associated with elevated presence of asthma triggers. As such, we hypothesized that elevated PM concentrations would be associated with decreased ventilation in the homes of asthmatic children.

Gravity-Current Driven Transport of Haze from North China Plain to Northeast China in Winter 2010-Part I: Observations

Haze exerts a large effect on visibility reduction and has serious impacts on air quality and human health. Understanding the sources and transport of haze is of importance to improve the regional air quality and evaluate its health effects. In this study, we investigated a typical haze episode that occurred in northeast (NE) China during 4-6 November 2010 by analyzing the ground PM10 measurements from 11 monitoring sites, aerosol Lidar observations, synoptic charts, MODIS satellite imageries, and back trajectories. Our analyses suggest that the regional haze formed in the North China Plain (NCP) under stagnant conditions can be transported to NE China in ∼1-3 days across Bohai Bay and Liaodong Bay - a typical transport pathway associated with the topography of northern China. The haze episode appeared to evolve progressively from southwest to northeast in the region of NE China, in agreement with the appearance of PM10 peak values, wind patterns, MODIS images and the back trajectories of air masses. Due to the haze impact, NE China showed significantly elevated particulate matter pollution by a factor of ∼4-6 with the peak concentrations reaching ∼410 μg m-3. The results together indicate that the regional transport from the NCP has a significant contribution to the PM pollution in NE China, thus efforts to control the source emissions over the NCP would be effective to improve the air quality in NE China.

Particulate Oxidative Burden Associated with Firework Activity

Firework events are capable of inducing particulate matter (PM) episodes that lead to exceedances of regulatory limit values. As short-term peaks in ambient PM concentration have been associated with negative impacts on respiratory and cardiovascular health, we performed a detailed study of the consequences of firework events in London on ambient air quality and PM composition. These changes were further related to the oxidative activity of daily PM samples by assessing their capacity to drive the oxidation of physiologically important lung antioxidants including ascorbate, glutathione and urate (oxidative potential, OP). Twenty-four hour ambient PM samples were collected at the Marylebone Road sampling site in Central London over a three week period, including two major festivals celebrated with pyrotechnic events: Guy Fawkes Night and Diwali. Pyrotechnic combustion events were characterized by increased gas phase pollutants levels (NO(x) and SO(2)), elevated PM mass concentrations, and trace metal concentrations (specifically Sr, Mg, K, Ba, and Pb). Relationships between NO(x), benzene, and PM(10) were used to apportion firework and traffic source fractions. A positive significant relationship was found between PM oxidative burden and individual trace metals associated with each of these apportioned source fractions. The level of exposure to each source fraction was significantly associated with the total OP. The firework contribution to PM total OP, on a unit mass basis, was greater than that associated with traffic sources: a 1 μg elevation in firework and traffic PM fraction concentration was associated with a 6.5 ± 1.5 OP(T) μg(-1) and 5.2 ± 1.4 OP(T) μg(-1) increase, respectively. In the case of glutathione depletion, firework particulate OP (3.5 ± 0.8 OP(GSH) μg(-1)) considerably exceeded that due to traffic particles (2.2 ± 0.8 OP(GSH) μg(-1)). Therefore, in light of the elevated PM concentrations caused by firework activity and the increased oxidative activity of this PM source, there is value in examining if firework derived PM is related to acute respiratory outcomes.

Measurements of particulate matter concentrations at a landfill site (Crete, Greece)

Large amounts of solid waste are disposed in landfills and the potential of particulate matter (PM) emissions into the atmosphere is significant. Particulate matter emissions in landfills are the result of resuspension from the disposed waste and other activities such as mechanical recycling and composting, waste unloading and sorting, the process of coating residues and waste transport by trucks. Measurements of ambient levels of inhalable particulate matter (PM 10) were performed in a landfill site located at Chania (Crete, Greece). Elevated PM 10 concentrations were measured in the landfill site during several landfill operations. It was observed that the meteorological conditions (mainly wind velocity and temperature) influence considerably the PM 10 concentrations. Comparison between the PM 10 concentrations at the landfill and at a PM 10 background site indicates the influence of the landfill activities on local concentrations at the landfill. No correlation was observed between the measurements at the landfill and the background sites. Finally, specific preventing measures are proposed to control the PM concentrations in landfills.