Component Of Fine Particulate Matter Research Articles

Ambient polycyclic aromatic hydrocarbons and pulmonary function in children.

Few studies have examined the relationship between ambient polycyclic aromatic hydrocarbons (PAHs) and pulmonary function in children. Major sources include vehicular emissions, home heating, wildland fires, agricultural burning, and power plants. PAHs are an important component of fine particulate matter that has been linked to respiratory health. This cross-sectional study examines the relationship between estimated individual exposures to the sum of PAHs with 4, 5, or 6 rings (PAH456) and pulmonary function tests (forced expiratory volume in one second (FEV1) and forced expiratory flow between 25% and 75% of vital capacity) in asthmatic and non-asthmatic children. We applied land-use regression to estimate individual exposures to ambient PAHs for averaging periods ranging from 1 week to 1 year. We used linear regression to estimate the relationship between exposure to PAH456 with pre- and postbronchodilator pulmonary function tests in children in Fresno, California (N=297). Among non-asthmatics, there was a statistically significant association between PAH456 during the previous 3 months, 6 months, and 1 year and postbronchodilator FEV1. The magnitude of the association increased with the length of the averaging period ranging from 60 to 110 ml decrease in FEV1 for each 1 ng/m(3) increase in PAH456. There were no associations with PAH456 observed among asthmatic children. We identified an association between annual PAHs and chronic pulmonary function in children without asthma. Additional studies are needed to further explore the association between exposure to PAHs and pulmonary function, especially with regard to differential effects between asthmatic and non-asthmatic children.

Multivariate spatial nonparametric modelling via kernel processes mixing

In this paper we develop a nonparametric multivariate spatial model that avoids specifying a Gaussian distribution for spatial random effects. Our nonparametric model extends the stick-breaking (SB) prior of Sethuraman (1994), which is frequently used in Bayesian modelling to capture uncertainty in the parametric form of an outcome. The stick-breaking prior is extended here to the spatial setting by assigning each location a different, unknown distribution, and smoothing the distributions in space with a series of space-dependent kernel functions that have a space-varying bandwidth parameter. This results in a flexible non-stationary spatial model, as different kernel functions lead to different relationships between the distributions at nearby locations. This approach is the first to allow both the probabilities and the point mass values of the SB prior to depend on space. Thus, there is no need for replications and we obtain a continuous process in the limit. We extend the model to the multivariate setting by having for each process a different kernel function, but sharing the location of the kernel knots across the different processes. The resulting covariance for the multivariate process is in general nonstationary and nonseparable. The modelling framework proposed here is also computationally efficient because it avoids inverting large matrices and calculating determinants, which often hinders the spatial analysis of large data sets. We study the theoretical properties of the proposed multivariate spatial process. The methods are illustrated using simulated examples and an air pollution application to model components of fine particulate matter.

EPA Proposes Tighter Particulate Air Pollution Standards

Particulate matter (PM) is one of six criteria pollutants regulated by National Ambient Air Quality Standards (NAAQS). These standards are twofold: a primary standard protects human health, and a secondary standard protects crops, ecosystems, and other forms of “public welfare.” The U.S. Environmental Protection Agency (EPA) last revisited the PM standards in 2006. Now, in response to a court order mandating action on the overdue review of these rules, the agency has proposed a stricter set of new standards.1 PM can be emitted directly from sources such as vehicles, power plants, burning biomass, and various industrial operations, or it can form as a reaction product. PM can contribute to a wide range of adverse health effects in people, with effects varying with the size and composition of the particles. Health damage occurs even in localities that meet current PM standards;2 the EPA’s advisory panel of independent experts, the Clean Air Scientific Advisory Committee (CASAC), noted in its correspondence with the agency regarding the proposed rules that “Although there is increasing uncertainty at lower levels [of PM exposure], there is no evidence of . . . a level below which there is no risk for adverse health effects.”3 For long-term effects of fine PM (PM2.5 ), CASAC recommended the primary health standard be tightened from a current annual average of 15 µg/m3 to somewhere in the range of 11–13 µg/m3.3 The EPA is proposing a standard in the range of 12–13 µg/m3 and is accepting public comments on levels down to 11 µg/m3. To address short-term effects, CASAC recommended a range of 30–35 µg/m3 averaged over 24 hours; the agency proposes to retain the current standard of 35 µg/m3. Particle size is an important factor in how PM affects human health. Larger PM10 is deposited mostly in the nose and throat. Because PM2.5 can penetrate much deeper into the lung, it poses a greater health threat. For coarse PM (PM10), the CASAC recommended the agency change not just the level of the standard but also its “form”—the air quality statistics used to determine whether an area is in compliance. The committee recommended adopting a level of 65–75 µg/m3 as the 98th percentile 24-hour concentration averaged over three years. The agency is proposing to keep the standard at the current 150 µg/m3 based on a so-called one-expected exceedance form—the 24-hour limit is not to be exceeded more than once a year averaged over three years. The agency estimates that at any point in the proposed ranges the dollars saved from avoided health costs, sick days, and deaths would far outweigh costs paid by affected states, tribal lands, and counties to achieve the lower standards.4 With PM2.5 standards of 13 µg/m3 (annual) and 35 µg/m3 (24-hour), the EPA calculates annual health benefits of $88–220 million, with costs of $2.9 million.5 Substituting an annual standard of 12 µg/m3, annual health benefits are estimated at $2.3–5.9 billion, with implementation costs of $69 million. At an annual standard of 11 µg/m3, annual health benefits would be an estimated $9.2–23.0 billion, with costs of $270 million. The agency also calculated a scenario with an annual standard of 11 µg/m3 and a 24-hour standard of 30 µg/m3. Both the benefits and implementation costs are estimated to be roughly 50% higher than the configuration of 11 µg/m3 (annual) and 35 µg/m3 (24-hour). About 30% of the U.S. population lives in the 191 counties or parts of counties designated as “nonattainment” for the current annual PM2.5 standard. Attainment status is based on a rolling three years’ worth of PM data for those counties with air monitors; for the rest, state and EPA officials must estimate each county’s contribution to the larger area’s PM pollution. In figures published with the proposed standards, the EPA estimated 33 counties with monitors (with total populations of more than 27 million) would violate an annual standard of 13 µg/m3, an additional 49 counties (with more than 27 million additional people) would violate 12 µg/m3, and an additional 86 counties (with tens of millions more people) would violate 11 µg/m3.6 These figures were based on 2008–2010 monitoring data. Ted Cromwell, senior principal for environmental policy at the National Rural Electric Cooperative Association, questions the wisdom of further tightening the standards without knowing which specific chemical constituents of PM2.5 are responsible for associated health effects.7 He’d prefer to continue implementation of the current standard until research more definitively pins down those substances, and then target them specifically. The EPA is reviewing public comments on the proposal and is required by the court-approved consent decree to issue final rules by 14 December 2012. Mitigation measures are supposed to begin by 2015 and must be fully implemented by 2020.

Global Bang for the Buck: Cutting Black Carbon and Methane Benefits Both Health and Climate

Black carbon and methane have both been implicated in climate change. They also pose more direct human health threats, with black carbon constituting one component of fine particulate matter (PM2.5) and methane acting as a precursor of ground-level ozone. An international team of researchers analyzed 14 control measures for human-caused emissions of black carbon and methane to investigate health benefits that might occur in tandem with actions to help mitigate climate change in the next 20–40 years [EHP 120(6):831–839; Anenberg et al.]. Black carbon and methane are attractive climate-change mitigation targets because they are relatively short-lived in the atmosphere compared with carbon dioxide, with emission restrictions leading to fairly rapid benefits. Some of the primary sources of methane are fossil-fuel extraction, landfills, livestock, rice production, and wastewater treatment. Among major sources of black carbon are many types of incomplete combustion, including that tied to transportation, industry, housing, and burning of biomass. The 14 measures target sources such as fossil-fuel operations, vehicle emissions, landfill gas, sewage, agriculture, brick kilns, and biomass-fueled cook stoves. Using published emissions scenarios as a basis for their calculations, the investigators estimate that if all 14 measures were fully implemented by 2030, average global population-weighted surface concentrations of PM2.5 could be reduced by 23–34% and ozone could drop 7–17% within the same period. That could prevent anywhere from 640,000 to 4,900,000 premature deaths annually, or about 1–7% of all deaths estimated to occur with the projected global population of 8.4 billion. The estimated health benefits would be due almost entirely to the black carbon control measures—with their attendant reductions in PM2.5, organic carbon, and non-methane ozone precursors—and would occur mostly in Asia and portions of Africa. Climate-change mitigation effects could have their own health benefits, although the authors didn’t attempt to calculate these. The authors accounted for just outdoor exposures from biomass-fueled cook stoves, not the well-documented health benefits of avoided indoor exposures; adding that information with a geographically appropriate distribution likely would substantially increase the number of avoided premature deaths. The researchers used two atmospheric models, each of which predicted substantially different air-quality responses to the 14 measures and incorporated a wide range of data from numerous epidemiological studies as factors in their equations. Uncertainties and variations in the models and data suggest the number of averted premature deaths could be substantially higher or lower. The researchers didn’t address the difficulties or costs of implementing the 14 measures but did note that some related efforts are already under way on many continents, including adoption of European vehicle-emission standards and reductions in cook-stove emissions in some developing countries.

Impacts of global, regional, and sectoral black carbon emission reductions on surface air quality and human mortality

Abstract. As a component of fine particulate matter (PM2.5), black carbon (BC) is associated with premature human mortality. BC also affects climate by absorbing solar radiation and reducing planetary albedo. Several studies have examined the climate impacts of BC emissions, but the associated health impacts have been studied less extensively. Here, we examine the surface PM2.5 and premature mortality impacts of halving anthropogenic BC emissions globally and individually from eight world regions and three major economic sectors. We use a global chemical transport model, MOZART-4, to simulate PM2.5 concentrations and a health impact function to calculate premature cardiopulmonary and lung cancer deaths. We estimate that halving global anthropogenic BC emissions reduces outdoor population-weighted average PM2.5 by 542 ng m−3 (1.8 %) and avoids 157 000 (95 % confidence interval, 120 000–194 000) annual premature deaths globally, with the vast majority occurring within the source region. Most of these avoided deaths can be achieved by halving emissions in East Asia (China; 54 %), followed by South Asia (India; 31 %), however South Asian emissions have 50 % greater mortality impacts per unit BC emitted than East Asian emissions. Globally, halving residential, industrial, and transportation emissions contributes 47 %, 35 %, and 15 % to the avoided deaths from halving all anthropogenic BC emissions. These contributions are 1.2, 1.2, and 0.6 times each sector's portion of global BC emissions, owing to the degree of co-location with population globally. We find that reducing BC emissions increases regional SO4 concentrations by up to 28 % of the magnitude of the regional BC concentration reductions, due to reduced absorption of radiation that drives photochemistry. Impacts of residential BC emissions are likely underestimated since indoor PM2.5 exposure is excluded. We estimate ∼8 times more avoided deaths when BC and organic carbon (OC) emissions are halved together, suggesting that these results greatly underestimate the full air pollution-related mortality benefits of BC mitigation strategies which generally decrease both BC and OC. The choice of concentration-response factor and health effect thresholds affects estimated global avoided deaths by as much as 56 % but does not strongly affect the regional distribution. Confidence in our results would be strengthened by reducing uncertainties in emissions, model parameterization of aerosol processes, grid resolution, and PM2.5 concentration-mortality relationships globally.

Toxicological Evaluation of Realistic Emission Source Aerosols (TERESA): Introduction and overview

Determining the health impacts of sources and components of fine particulate matter (PM2.5) is an important scientific goal. PM2.5 is a complex mixture of inorganic and organic constituents that are likely to differ in their potential to cause adverse health outcomes. The Toxicological Evaluation of Realistic Emissions of Source Aerosols (TERESA) study focused on two PM sources—coal-fired power plants and mobile sources—and sought to investigate the toxicological effects of exposure to emissions from these sources. The set of papers published here document the power plant experiments. TERESA attempted to delineate health effects of primary particles, secondary (aged) particles, and mixtures of these with common atmospheric constituents. TERESA involved withdrawal of emissions from the stacks of three coal-fired power plants in the United States. The emissions were aged and atmospherically transformed in a mobile laboratory simulating downwind power plant plume processing. Toxicological evaluations were carried out in laboratory rats exposed to different emission scenarios with extensive exposure characterization. The approach employed in TERESA was ambitious and innovative. Technical challenges included the development of stack sampling technology that prevented condensation of water vapor from the power plant exhaust during sampling and transfer, while minimizing losses of primary particles; development and optimization of a photochemical chamber to provide an aged aerosol for animal exposures; development and evaluation of a denuder system to remove excess gaseous components; and development of a mobile toxicology laboratory. This paper provides an overview of the conceptual framework, design, and methods employed in the study.

Multilateral Efforts to Reduce Black Carbon Emissions: A Lifeline for the Warming Arctic?

Rapid reductions in emissions of the short‐lived climate forcers black carbon, tropospheric ozone and methane have been identified as an effective strategy to slow rapid warming and melting in the Arctic and other glaciated areas in the near‐term, and avert abrupt, irreversible changes while strategies to reduce emissions of CO2 are implemented to limit long‐term consequences. Black carbon is a component of fine particulate matter, a traditional air pollutant with significant health impacts; it has a short atmospheric residence time of about a week, thus emissions reductions provide rapid climate benefit. This article analyses the mitigation approaches that are being discussed in multilateral fora including the Arctic Council, the Convention on Long Range Transboundary Air Pollution and the International Maritime Organization. Arctic climate dynamics will affect climate globally, which calls for leadership from Arctic nations to spur faster action to abate emissions.

Air Pollution and Health: Bridging the Gap from Sources to Health Outcomes

The U.S. Environmental Protection Agency (EPA) has established National Ambient Air Quality Standards (NAAQS) for six principal air pollutants (“criteria” pollutants): carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), particulate matter (PM) in two size ranges [< 2.5 μm (PM2.5) and < 10 μm (PM10)], ozone (O3), and sulfur dioxide (SO2) (U.S. EPA 2010b). Although associations have been identified between these pollutants and adverse health effects, considerable uncertainty remains regarding a) methods and approaches to understanding relationships between air pollution and health effects; b) which components (gas and/or aerosol) and sources are most toxic; c) the mechanisms of actions of the pollutants and causal relationships; d) effect of confounding factors, and e) which populations are susceptible {U.S. EPA 2006a (Pb), 2006b (O3), 2008a [NOx Integrated Science Assessment (ISA)], 2008b (SOx ISA), 2009 (PM), 2010 (CO)}. This holds true especially for PM, because it is composed of many components with significant spatial and temporal variation (U.S. EPA 2009). Air pollution and health research continues to reduce these uncertainties across the source-to-health effects paradigm as described by the National Research Council (NRC) Research Priorities for Airborne Particulate Matter, volumes I–IV, (NRC 1998, 1999, 2001, 2004) and the U.S. EPA (2006a, 2006b, 2008a, 2008b, 2009b, 2010a). Linking air pollution and adverse health effects is complicated and requires expertise across a range of scientific disciplines—from atmospheric to exposure to health sciences, as well as inclusion of air quality managers and policy makers who implement and develop policy to reduce risk from air pollution. Interaction among these groups at different points in time helps to identify gaps in knowledge and suggest future research directions. One such opportunity was the international specialty conference “Air Pollution and Health: Bridging the Gap from Sources to Health Outcomes,” sponsored by the American Association for Aerosol Research (AAAR 2010). The conference, chaired by myself and Maria Costantini (Health Effects Institute), was designed to help disseminate and integrate results from scientific studies that cut across the range of air pollution– and health-related disciplines of the source-to-health effects continuum. The conference addressed the science of air pollution and health within a multipollutant framework, focusing on five key science areas—sources, atmospheric sciences, exposure, dose, and health effects—as identified by the NRC (1998). Eight key policy-relevant science questions that integrated across various parts of these science areas formed the basis of the meeting, and a ninth question addressed the policy implications of the findings (see Appendix). This was the AAAR’s third international specialty conference and extended the findings presented at the AAAR’s first specialty conference “Particulate Matter: Atmospheric Sciences, Exposure, and the Fourth Colloquium on PM and Human Health,” held in Pittsburgh, Pennsylvania, in 2003 (Davidson et al. 2005). Results from the 2010 AAAR Air Pollution and Health conference are being published in Environmental Health Perspectives (EHP); Air Quality, Atmosphere and Health; Aerosol Science and Technology; Atmospheric Environment; and Inhalation Toxicology (Solomon 2010). This issue of EHP includes conference papers on the importance of a multipollutant approach and of individual components of particulate matter to understanding linkages between sources and adverse health outcomes, including respiratory and/or cardiovascular diseases (Ito et al. 2011; Lall et al. 2011; Rohr et al. 2011; Spira-Cohen et al. 2011; Zhou et al. 2011), associated effects, such as inflammation (Alexeeff et al. 2011), and birth outcomes associated with exposures to traffic-related pollution during gestation (Malmqvist et al. 2011). Several air pollution components and sources were evaluated, including elemental carbon and secondary organic aerosol, traffic, local industrial sources, and residential oil and wood burning. Where studied, some effects varied by season and location over sufficient time (specifically, Detroit, MI; Seattle, WA; New York, NY), likely due to the influence of different source impacts. In addition, this issue includes a review of population characteristics related to susceptibility (Sacks et al. 2011), and an accountability study of the feasibility of hybrid regional–local modeling to assess health improvements in small communities (Lobdell et al. 2011).

Time-Series Analysis of Mortality Effects of Fine Particulate Matter Components in Detroit and Seattle

BackgroundRecent toxicological and epidemiological studies have shown associations between particulate matter (PM) and adverse health effects, but which PM components are most influential is less well known.ObjectivesIn this study, we used time-series analyses to determine the associations between daily fine PM [PM ≤ 2.5 μm in aerodynamic diameter (PM2.5)] concentrations and daily mortality in two U.S. cities—Seattle, Washington, and Detroit, Michigan.MethodsWe obtained daily PM2.5 filters for the years of 2002–2004 and analyzed trace elements using X-ray fluorescence and black carbon using light reflectance as a surrogate measure of elemental carbon. We used Poisson regression and distributed lag models to estimate excess deaths for all causes and for cardiovascular and respiratory diseases adjusting for time-varying covariates. We computed the excess risks for interquartile range increases of each pollutant at lags of 0 through 3 days for both warm and cold seasons.ResultsThe cardiovascular and respiratory mortality series exhibited different source and seasonal patterns in each city. The PM2.5 components and gaseous pollutants associated with mortality in Detroit were most associated with warm season secondary aerosols and traffic markers. In Seattle, the component species most closely associated with mortality included those for cold season traffic and other combustion sources, such as residual oil and wood burning.ConclusionsThe effects of PM2.5 on daily mortality vary with source, season, and locale, consistent with the hypothesis that PM composition has an appreciable influence on the health effects attributable to PM.

Source–receptor relationships for fine particulate matter concentrations in the Eastern United States

The Particulate Matter Source Apportionment (PSAT) method is used to quantify the impacts of different source regions on fine particulate matter (PM) concentrations in the Eastern United States. Our analysis focuses both on how far pollutants are transported and the impacts they have in the corresponding receptor areas. Towards this goal, several quantitative measures of impact and transport distance are proposed and calculated for ten source regions for all seasons. The long range source impacts are extremely variable in space and time and are often in directions different than that of the average prevailing winds. Transport distances were usually lower during the summer than in other seasons for this region. The average transport distance (distance from the source area to the center of the pollution plume) for elemental carbon and other primary fine PM components was found to be 100–200 km for most source regions. On the other hand, the secondary PM species were found to be transported the furthest with sulfate and secondary organic aerosol (SOA) traveling on average over 350 km. Maximum transport distances are significant higher, with sulfate impacts reaching as far as 2000 km away from the SO2 source region. The fractional contribution of a source region to fine PM ground level concentrations can be quite different (up to a factor of 3) than its emission contribution. This is mainly due to the height where the emissions are released. Regions with mainly ground level emissions contribute more while regions with elevated emissions less than the magnitude of their emissions suggests.

Hexavalent chromium inhibited the expression of RKIP of heart in vivo and in vitro

Background Chromium (Cr) is considered to be a risk factor to the cardiovascular effects of fine particulate matter components to PM2 .5 from traffic in highway patrol officers. RKIP (raf kinase inhibitor protein) is a physiological inhibitor of GRK-2 (G-protein-coupled receptor kinase 2) and affects β-adrenergic signaling and contractile activity in cardiomyocytes. Objectives In this study, we explored the change of RKIP in heart of chromium (VI)-exposed rats and cultured myocardial cells with chromium (VI) treatment. Method Wistar rats were divided into six groups which were chronically fed with 250, 500, 750, 1000, and 1250 ppm Na 2Cr 2O 7 and water for 60 days, respectively. Na 2Cr 2O 7 dose of 0.25, 0.5, 1.5, 3, 4.5, and 0 ppm (control group) was applied in cultured myocardial cells. The level of heart Cr (VI) was determined by electrothermal atomic absorption spectrometry. The expression of RKIP was measured by Western blot method. The MTT assay was used to measure the toxicity of myocardial cells with Cr (VI) treatment. The apoptosis test of myocardial cells was determined by caspase-3 colorimetric assay kit. Result The result showed that the expression of RKIP in heart ( in vivo) and myocardial cells ( in vitro) was decreased following Cr (VI) dose-dependent treatment. Conclusion We suggested that the decrement of RKIP of heart and myocardial cells with Cr (VI) treatment resulted in the function of cardiovascular system decreased.

Assessing the spatial and temporal variability of fine particulate matter components in Israeli, Jordanian, and Palestinian cities

This manuscript presents results from an extensive, multi-country comparative monitoring study of fine particulate matter (PM 2.5) and its primary chemical components in Israeli, Jordanian and Palestinian cities. This study represented the first time that researchers from these countries have worked together to examine spatial and temporal relationships for PM 2.5 and its major components among the study sites. The findings indicated that total PM 2.5 mass was relatively homogenous among many of the 11 sites as shown from strong between-site correlations. Mean annual concentrations ranged from 19.9 to 34.9 μg m −3 in Haifa and Amman, respectively, and exceeded accepted international air quality standards for annual PM 2.5 mass. Similarity of total mass was largely driven by SO 4 2− and crustal PM 2.5 components. Despite the close proximity of the seven, well correlated sites with respect to PM 2.5, there were pronounced differences among the cities for EC and, to a lesser degree, OC. EC, in particular, exhibited spatiotemporal trends that were indicative of strong local source contributions. Interestingly, there were moderate to strong EC correlations ( r > 0.65) among the large metropolitan cities, West Jerusalem, Tel Aviv and Amman. For these relatively large cities, (i.e., West Jerusalem, Tel Aviv and Amman), EC sources from the fleet of buses and cars typical for many urban areas predominate and likely drive spatiotemporal EC distributions. As new airshed management strategies and public health interventions are implemented throughout the Middle East, our findings support regulatory strategies that target integrated regional and local control strategies to reduce PM 2.5 mass and specific components suspected to drive adverse health effects of particulate matter exposure.

The impact of components of fine particulate matter on cardiovascular mortality in susceptible subpopulations

Background: Several studies have demonstrated associations between daily mortality and ambient particulate matter less than 2.5 microns in diameter (fine particles or PM2.5). Few, however, have examined the relative toxicities...

Primary and secondary components of PM2.5 in Milan (Italy)

In sampling campaigns – carried out by means of a high-volume gravimetric sampler – performed between August 2002 and December 2003, 24-h PM2.5 samples have been collected at an urban background site in downtown Milan and analyzed for elemental and organic carbon, ionic species (i.e., chloride, nitrates, sulfates and ammonium) and some elemental species. Chemical speciation data are evaluated also in terms of primary and secondary components of fine particulate matter: in particular, the contribution of secondary organic aerosols (SOA) and of the primary contribution from traffic to observed PM2.5 concentration levels are evaluated by means of the EC tracer method.

Semi-continuous mass closure of the major components of fine particulate matter in Riverside, CA

The application of newly developed semi-continuous aerosol monitors allows for the measurement of all the major species of PM 2.5 on a 1-h time basis. Temporal resolution of both non-volatile and semi-volatile species is possible. A suite of instruments to measure the major chemical species of PM 2.5 allows for semi-continuous mass closure. A newly developed dual-oven Sunset carbon monitor is used to measure non-volatile organic carbon, semi-volatile organic carbon and elemental carbon. Inorganic species, including sulfate and nitrate, can be measured with an ion chromatograph based sampler. Comparison of the sum of the major chemical species in an urban aerosol with mass measured by an FDMS resulted in excellent agreement. Linear regression analysis resulted in a zero-intercept slope of 0.98±0.01 with an R 2=0.86. One-hour temporal resolution of the major species of PM 2.5 may reduce the uncertainty in receptor based source apportionment modeling, will allow for better forecasting of PM 2.5 episodes, and may lead to increased understanding of related health effects.

Exploring relationships between outdoor air particulate-associated polycyclic aromatic hydrocarbon and PM 2.5: 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 R 2 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 R 2 of 0.55. These R 2-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.

The Health Impact of Common Inorganic Components of Fine Particulate Matter (PM2.5) in Ambient Air: A Critical Review

Ambient air particulate matter (PM) originates as either primary particles emitted directly into the atmosphere from a specific source or as secondary particles produced from atmospheric chemical reactions between precursor gases or between these gases and primary particles. PM can derive from both natural and anthropogenic sources, resulting in a complex chemical mix. The “fine” size mode of ambient PM, designated as PM2.5, is defined as comprising those particles having aerodynamic diameters below 2.5 μm. While the total mass of PM2.5 has been associated with adverse human health outcomes, the relationship between these and specific chemical components has not been resolved. This article provides a perspective on the current state of the science concerning health effects from a major group of chemical species found within PM2.5, namely common inorganic constituents. The specific chemical classes discussed herein are secondary inorganic species, namely, sulfate, nitrate, and acidity, and generally crustal-derived species, namely, phosphate, sodium, potassium, calcium, magnesium, silicon, and aluminum. The article discusses evidence for adverse health effects from inorganic PM2.5 components within the framework of various caveats surrounding both epidemiology and toxicology assessments. The largest database exists for sulfate, but conclusions that attribute sulfate to health outcomes have not been consistent across all epidemiology studies, and there is a lack of coherence with toxicology studies, which show biological responses only at high levels of exposure. Limited epidemiological and toxicological data for nitrate suggests little or no adverse health effects at current levels. Epidemiological studies specifically identifying crustal components of PM2.5 suggest that they are not likely, by themselves, to produce a significant health risk, and these components do not have unequivocal biological plausibility from toxicological studies for being significant contributors to adverse health outcomes.

Cardiovascular Effects of Fine Particulate Matter Components in Highway Patrol Officers

Exposure to fine particulate matter (PM2.5) from traffic affects heart-rate variability, thrombosis, and inflammation. This reanalysis investigated components potentially contributing to such effects in nonsmoking healthy male North Carolina highway patrol troopers. Nine officers were studied four times during their late shift. PM2.5, its elemental composition, and gaseous copollutants were measured inside patrol cars. Components correlated to PM2.5 were compared to cardiac and blood parameters measured 10 and 15 h, respectively, after each shift. Mixed effects models with control for PM2.5 were used. Components that were associated with health endpoints independently from PM2.5 were calcium (increased uric acid and von Willebrand Factor [vWF], decreased protein C), chromium (increased white blood cell count and interleukin 6), aldehydes (increased vWF, mean cycle length of normal R-R intervals [MCL], and heart-rate variability parameter pNN50), copper (increased blood urea nitrogen and MCL; decreased plasminogen activator inhibitor 1), and sulfur (increased ventricular ectopic beats). Control for gaseous copollutants had little effect on the effect estimates. The changes observed are consistent with effects reported earlier for PM2.5 from speed-change traffic (characterized by copper, sulfur, and aldehydes) and from soil (with calcium). The associations of chromium with inflammation markers were not seen before for traffic particles, but they are consistent with the toxicological literature although at low concentrations. Copper, sulfur, aldehydes, calcium, and chromium or compounds containing these elements seem to directly contribute to the inflammatory, coagulatory, and cardiac response to PM2.5 from traffic in the investigated patrol troopers.

Ambient Air Pollution and Cardiorespiratory Events in High-Risk Infants Using Home Monitors

TM6-O-01 Session Title: Air Pollution: Short-term Cardiovascular Effects Introduction: Identifying populations that are susceptible to the acute adverse health effects of ambient pollutants is a priority in air pollution research. The few studies that have examined infants suggest that ambient air pollution levels are associated with cardiorespiratory outcomes in this age group, but the studies have been generally limited in power and in health outcome information. The associations of daily ambient air pollution levels with apnea and bradycardia were examined in infants prescribed home cardiorespiratory monitors from 1998 through 2002, followed at one of the largest referral centers for home monitoring in the country. This is a novel population for air pollution studies and allows for examination of a potentially susceptible group. Methods: The monitors record the electrocardiogram, heart rate, and impedence for detected events. Collected data include type, date, time, and duration of each event, gender, date of birth, gestational age at birth, and birth weight. We assessed these events in relation to speciated particulate matter levels as well as gaseous air pollution levels, using a 2-day average of air pollution lagged zero and one day. Odds ratios (OR) and confidence intervals (CI) were calculated per standard deviation increase in pollution levels. Results: In preliminary analyses, 4277 infants had 8960 apnea event-days and 29,450 bradycardia event-days in over 179,000 days of follow-up. Our analysis used generalized estimating equations, controlling for time trends, temperature, age of the infant, weekends, and federal holidays as well as residual correlation within subject. Preliminary results show associations between bradycardia and ozone (OR, 1.049 per 25 ppb; 95% CI, 1.021–1.078) and nitrogen dioxide (OR, 1.025 per 20 ppb; 95% CI, 1.000–1.050). The association with ozone was robust to various methods of control for time trend and specified correlation structure. Associations with other pollutants, as well as associations for apnea events, were consistent with a null association. In secondary analyses, apnea events in full term and normal birth weight infants were associated with increased levels of the organic carbon component of fine particulate matter (OR = 1.091 per 2 μg/m3, 95% CI, 1.002–1.186); associations for preterm and low birth weight infants were consistent with a null association. Discussion: These results suggest that infants who are at high risk for apnea and bradycardia may be susceptible to the adverse health effects of ambient air pollution.

Characterization of Major Chemical Components of Fine Particulate Matter in North Carolina

This paper presents measurements of daily sampling of fine particulate matter (PM2.5) and its major chemical components at three urban and one rural locations in North Carolina during 2002. At both urban and rural sites, the major insoluble component of PM2.5 is organic matter, and the major soluble components are sulfate (SO4 2−), ammonium (NH4 +), and nitrate (NO3 −). NH4 + is neutralized mainly by SO4 2− rather than by NO3 −, except in winter when SO4 2− concentration is relatively low, whereas NO3 − concentration is high. The equivalent ratio of NH4 + to the sum of SO4 2− and NO3 − is <1, suggesting that SO4 2−and NO3 −are not completely neutralized by NH4 +. At both rural and urban sites, SO4 2−concentration displays a maximum in summer and a minimum in winter, whereas NO3 −displays an opposite seasonal trend. Mass ratio of NO3 − to SO4 2−is consistently <1 at all sites, suggesting that stationary source emissions may play an important role in PM2.5 formation in those areas. Organic carbon and elemental carbon are well correlated at three urban sites although they are poorly correlated at the agriculture site. Other than the daily samples, hourly samples were measured at one urban site. PM2.5 mass concen trations display a peak in early morning, and a second peak in late afternoon. Back trajectory analysis shows that air masses with lower PM2.5 mass content mainly originate from the marine environment or from a continental environment but with a strong subsidence from the upper troposphere. Air masses with high PM2.5 mass concentrations are largely from continental sources. Our study of fine particulate matter and its chemical composition in North Carolina provides crucial information that may be used to determine the efficacy of the new National Ambient Air Quality Standard (NAAQS) for PM fine. Moreover, the gas-to-particle conversion processes provide improved prediction of long-range transport of pollutants and air quality.