Constituents Of PM2 Research Articles

Long-term exposure to elemental constituents of particulate matter and cardiovascular mortality in 19 European cohorts: Results from the ESCAPE and TRANSPHORM projects

BackgroundAssociations between long-term exposure to ambient particulate matter (PM) and cardiovascular (CVD) mortality have been widely recognized. However, health effects of long-term exposure to constituents of PM on total CVD mortality have been explored in a single study only. AimsThe aim of this study was to examine the association of PM composition with cardiovascular mortality. MethodsWe used data from 19 European ongoing cohorts within the framework of the ESCAPE (European Study of Cohorts for Air Pollution Effects) and TRANSPHORM (Transport related Air Pollution and Health impacts — Integrated Methodologies for Assessing Particulate Matter) projects. Residential annual average exposure to elemental constituents within particle matter smaller than 2.5 and 10μm (PM2.5 and PM10) was estimated using Land Use Regression models. Eight elements representing major sources were selected a priori (copper, iron, potassium, nickel, sulfur, silicon, vanadium and zinc). Cohort-specific analyses were conducted using Cox proportional hazards models with a standardized protocol. Random-effects meta-analysis was used to calculate combined effect estimates. ResultsThe total population consisted of 322,291 participants, with 9545 CVD deaths. We found no statistically significant associations between any of the elemental constituents in PM2.5 or PM10 and CVD mortality in the pooled analysis. Most of the hazard ratios (HRs) were close to unity, e.g. for PM10 Fe the combined HR was 0.96 (0.84–1.09). Elevated combined HRs were found for PM2.5 Si (1.17, 95% CI: 0.93–1.47), and S in PM2.5 (1.08, 95% CI: 0.95–1.22) and PM10 (1.09, 95% CI: 0.90–1.32). ConclusionIn a joint analysis of 19 European cohorts, we found no statistically significant association between long-term exposure to 8 elemental constituents of particles and total cardiovascular mortality.

Effects of fine particulate matter and its constituents on low birth weight among full-term infants in California

Background: Prenatal exposure to fine particles (PM2.5) and low birth weight (LBW; <2,500 grams) has been described previously. Very few studies have considered the constituents of PM2.5, which may...

SPATIOTEMPORAL VARIATION OF PARTICLE NUMBER AND SURFACE AREA CONCENTRATION IN FOUR SWISS AREAS AND ITS RELATIONSHIP WITH MASS MEASUREMENTS

Background: This study is part of the Swiss Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA), a cohort study initiated in 1990 and spread across eight geographically diverse areas in Switzerland. Innovative exposure modeling has been conducted in SAPALDIA earlier for PM10 and NO2, however, exposure to specific traffic related pollutants such as ultrafine particles and PM constituents has not been assessed. Aims:The overarching aim is to provide the estimates of individual long-term outdoor traffic-related air pollution exposures of the cohort participants. This paper focuses on the spatial and temporal variation of home outdoor particle number (PN) and lung-deposited surface area (LDSA) concentration in four study areas: Basel, Geneva, Lugano and Wald. Methods: Weekly outdoor PN and LDSA are measured at 20 residences each in four study areas in three seasons over a period of 2 years, 2011-2012. PN and LDSA are measured using a portable particle counter, miniDiSC (miniature diffusion size classifier). It is a portable diffusion charging based device and measures nanometer sized (10-300nm) particles with a time-resolution of one second. Results: Mean weekly outdoor PN levels aggregated across all seasons and sites are 11000±3700, 15400±8430 and 15700±7200 particles/cm3 in Basel, Geneva and Lugano, respectively. As expected, PN are highest in winter and lowest in summer for all study areas/sites. PN levels show a clear morning and evening rush hour in all seasons in all sites, but more prominently at street sites. PN shows reasonably moderate correlation with NO2 but poor to no correlation with other PM mass metrics in all seasons. Analysis of LDSA measurements and comparison with PN and other pollutants is currently underway. Conclusions: Our results show significant seasonal and spatial variation in home outdoor PN levels within and between study areas and document the differential impact of traffic on PN levels in all study areas.

Short-term Exposure to Particulate Matter Constituents and Mortality in a National Study of U.S. Urban Communities

Background: Although the association between PM2.5 mass and mortality has been extensively studied, few national-level analyses have estimated mortality effects of PM2.5 chemical constituents. Epidemiologic studies have reported that estimated effects of PM2.5 on mortality vary spatially and seasonally. We hypothesized that associations between PM2.5 constituents and mortality would not vary spatially or seasonally if variation in chemical composition contributes to variation in estimated PM2.5 mortality effects.Objectives: We aimed to provide the first national, season-specific, and region-specific associations between mortality and PM2.5 constituents.Methods: We estimated short-term associations between nonaccidental mortality and PM2.5 constituents across 72 urban U.S. communities from 2000 to 2005. Using U.S. Environmental Protection Agency (EPA) Chemical Speciation Network data, we analyzed seven constituents that together compose 79–85% of PM2.5 mass: organic carbon matter (OCM), elemental carbon (EC), silicon, sodium ion, nitrate, ammonium, and sulfate. We applied Poisson time-series regression models, controlling for time and weather, to estimate mortality effects.Results: Interquartile range increases in OCM, EC, silicon, and sodium ion were associated with estimated increases in mortality of 0.39% [95% posterior interval (PI): 0.08, 0.70%], 0.22% (95% PI: 0.00, 0.44), 0.17% (95% PI: 0.03, 0.30), and 0.16% (95% PI: 0.00, 0.32), respectively, based on single-pollutant models. We did not find evidence that associations between mortality and PM2.5 or PM2.5 constituents differed by season or region.Conclusions: Our findings indicate that some constituents of PM2.5 may be more toxic than others and, therefore, regulating PM total mass alone may not be sufficient to protect human health.Citation: Krall JR, Anderson GB, Dominici F, Bell ML, Peng RD. 2013. Short-term exposure to particulate matter constituents and mortality in a national study of U.S. urban communities. Environ Health Perspect 121:1148–1153; http://dx.doi.org/10.1289/ehp.1206185

Examining the effects of air pollution composition on within region differences in PM2.5 mortality risk estimates

Multi-city population-based epidemiological studies have observed significant heterogeneity in both the magnitude and direction of city-specific risk estimates, but tended to focus on regional differences in PM2.5 mortality risk estimates. Interpreting differences in risk estimates is complicated by city-to-city heterogeneity observed within regions due to city-to-city variations in the PM2.5 composition and the concentration of gaseous pollutants. We evaluate whether variations in PM2.5 composition and gaseous pollutant concentrations have a role in explaining the heterogeneity in PM2.5 mortality risk estimates observed in 27 US cities from 1997 to 2002. Within each region, we select the two cities with the largest and smallest mortality risk estimate. We compare for each region the within- and between-city concentrations and correlations of PM2.5 constituents and gaseous pollutants. We also attempt to identify source factors through principal component analysis (PCA) for each city. The results of this analysis indicate that identifying a PM constituent(s) that explains the differences in the PM2.5 mortality risk estimates is not straightforward. The difference in risk estimates between cities in the same region may be attributed to a group of pollutants, possibly those related to local sources such as traffic.

A Meta-Analysis and Multisite Time-Series Analysis of the Differential Toxicity of Major Fine Particulate Matter Constituents

Health risk assessments of particulate matter less than 2.5 μm in diameter (PM(2.5)) often assume that all constituents of PM(2.5) are equally toxic. While investigators in previous epidemiologic studies have evaluated health risks from various PM(2.5) constituents, few have conducted the analyses needed to directly inform risk assessments. In this study, the authors performed a literature review and conducted a multisite time-series analysis of hospital admissions and exposure to PM(2.5) constituents (elemental carbon, organic carbon matter, sulfate, and nitrate) in a population of 12 million US Medicare enrollees for the period 2000-2008. The literature review illustrated a general lack of multiconstituent models or insight about probabilities of differential impacts per unit of concentration change. Consistent with previous results, the multisite time-series analysis found statistically significant associations between short-term changes in elemental carbon and cardiovascular hospital admissions. Posterior probabilities from multiconstituent models provided evidence that some individual constituents were more toxic than others, and posterior parameter estimates coupled with correlations among these estimates provided necessary information for risk assessment. Ratios of constituent toxicities, commonly used in risk assessment to describe differential toxicity, were extremely uncertain for all comparisons. These analyses emphasize the subtlety of the statistical techniques and epidemiologic studies necessary to inform risk assessments of particle constituents.

Characterization of Fine Particulate Matter and Associations between Particulate Chemical Constituents and Mortality in Seoul, Korea

Background: Numerous studies have linked fine particles [≤ 2.5 µm in aerodynamic diameter (PM2.5)] and health. Most studies focused on the total mass of the particles, although the chemical composition of the particles varies substantially. Which chemical components of fine particles that are the most harmful is not well understood, and research on the chemical composition of PM2.5 and the components that are the most harmful is particularly limited in Asia.Objectives: We characterized PM2.5 chemical composition and estimated the effects of cause-specific mortality of PM2.5 mass and constituents in Seoul, Korea. We compared the chemical composition of particles to those of the eastern and western United States.Methods: We examined temporal variability of PM2.5 mass and its composition using hourly data. We applied an overdispersed Poisson generalized linear model, adjusting for time, day of week, temperature, and relative humidity to investigate the association between risk of mortality and PM2.5 mass and its constituents in Seoul, Korea, for August 2008 through October 2009.Results: PM2.5 and chemical components exhibited temporal patterns by time of day and season. The chemical characteristics of Seoul’s PM2.5 were more similar to PM2.5 found in the western United States than in the eastern United States. Seoul’s PM2.5 had lower sulfate (SO4) contributions and higher nitrate (NO3) contributions than that of the eastern United States, although overall PM2.5 levels in Seoul were higher than in the United States. An interquartile range (IQR) increase in magnesium (Mg) (0.05 μg/m3) was associated with a 1.4% increase (95% confidence interval: 0.2%, 2.6%) in total mortality on the following day. Several components that were among the largest contributors to PM2.5 total mass—NO3, SO4, and ammonium (NH4)—were moderately associated with same-day cardiovascular mortality at the p < 0.10 level. Other components with smaller mass contributions [Mg and chlorine (Cl)] exhibited moderate associations with respiratory mortality on the following day (p < 0.10).Conclusions: Our findings link PM2.5 constituents with mortality and have implications for policy making on sources of PM2.5 and on the relevance of PM2.5 health studies from other areas to this region.

Insulinotrophic and insulin-like effects of a high molecular weight aqueous extract of Pterocarpus marsupium Roxb. hardwood

Ethnopharmacological relevancePterocarpus marsupium Roxb. (PM) is an Ayurvedic traditional medicine well known for its antidiabetic potential. AimTo fractionate the antidiabetic constituent(s) of the aqueous of extract of PM hardwood (PME). Materials and methodsBio-assay methods including, insulin secretion from mouse pancreas and glucose uptake by mouse skeletal muscle, were used to determine and fractionate the antidiabetic activity of PME. Results obtained from the in vitro experiments were then verified by examining the effect of PME on glucose clearance in normoglycemic, non-diabetic sheep in vivo. ResultsExposure of mouse pancreatic and muscle tissues to PME stimulated the insulin secretion and glucose uptake, respectively, in a concentration-dependent manner. PME-mediated muscle glucose uptake was not potentiated in the presence of insulin indicating that PME acts via pathways which are utilized by insulin. Bio-assay-guided fractionation of PME yielded a high molecular weight fraction which had potent antidiabetic properties in vitro, and in in vivo. ConclusionsOur findings, we believe for the first time, provide novel insights for the antidiabetic constituents of PM and demonstrate that a high molecular weight constituent(s) of PM has potent insulinotrophic and insulin-like properties.

Chemical characteristics of aerosols and trace gas distribution over North and Central India

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi-Hyderabad-Delhi road corridor (spanning about 3,200 km) in India, during February 1-29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM(10)) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na(+), Ca(2+), Mg(2+), K(+), and NH (4) (+)), anions (Cl(-), NO (3)(-), and SO (4)(2-)), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO(2) and SO(2) gases. These species show large spatial and temporal variations. The ambient PM(10) concentration has been observed to be the highest (55 ± 4 μg m(-3)) near semi-urban areas followed by forest areas (48 ± 2 μg m(-3)) and in rural areas (44 ± 22 μg m(-3)). The concentrations of NO( x ) (NO(2)+NO) and SO(2) ranged from 16 to 69 μg m(-3) and 4 to 11 μg m(-3), respectively. Among anions, NO(3)(-) and SO(4) (2-) are the major constituents of PM(10). The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.

SPATIO-TEMPORAL VARIATION OF PARTICLE NUMBER CONCENTRATIONS IN A SWISS URBAN CITY

Background and Aims: This study is part of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA), a nearly 20-year old cohort study spread in 8 geographically diverse areas in Switzerland. Innovative exposure modeling has been conducted in SAPALDIA earlier for PM10 and NO2, however, exposure to specific traffic related pollutants such as ultrafine particles and PM constituents has not been assessed. The overarching aim is to provide the estimates of individual long-term outdoor traffic-related air pollution exposures of the cohort participants. This paper focuses on the spatial and temporal variation of home outdoor particle number concentration (PN) in one of the SAPALDIA area, Basel. Methods: The PN measurements will be conducted at 20 residences each in four of the eight areas in three seasons over a period of 2 years, 2011-2012. Indoors and outdoors monitoring will be conducted biweekly for PM2.5, PM10, NO2 and weekly for PN. Particle counts are measured using a particle counting device, miniDiSC (miniature diffusion size classifier). It is a portable device and measures nanometer sized (10-300nm) particles with a resolution of one second. Results: Mean weekly averaged PN levels are observed 14529±3296, 13659±1878 and 11545 particles/cm3 at street, urban and regional background locations respectively. Median correlation coefficient for all sites is 0.70 (range 0.36-0.91) and 0.83 (range 0.39-0.99) for hourly and daily PN respectively. Median coefficient of divergence, a measure of spatial heterogeneity, for all site pairs is 0.15 (range 0.05-0.27), showing a low to mid spatial heterogeneity in daily PN in Basel. These winter season observations will be compared across seasons and further with concurrent PM2.5, PM10 and NO2 measurements. Conclusions: Our first results show significant differences in PN levels in home outdoor locations and document the differential impact of traffic on PN levels in the city.

PM2.5-induced changes in cardiac function of hypertensive rats depend on wind direction and specific sources in Steubenville, Ohio

Background: Increases in particulate matter less than 2.5 µm (PM2.5) in ambient air is linked to acute cardiovascular morbidity and mortality. Specific components and potential emission sources of PM2.5 responsible for adverse health effects of cardiovascular function are unclear.Methods: Spontaneously hypertensive rats were implemented with radiotelemeters to record ECG responses during inhalation exposure to concentrated ambient particles (CAPs) for 13 consecutive days in Steubenville, OH. Changes in heart rate (HR) and its variability (HRV) were compared to PM2.5 trace elements in 30-min time frames to capture acute physiological responses with real-time fluctuations in PM2.5 composition. Using positive matrix factorization, six major source factors were identified: (i) coal/secondary, (ii) mobile sources, (iii) metal coating/processing, (iv) iron/steel manufacturing, (v) lead and (vi) incineration.Results: Exposure-related changes in HR and HRV were dependant on winds predominately from either the northeast (NE) or southwest (SW). During SW winds, the metal processing factor was associated with increased HR, whereas factors of incineration, lead and iron/steel with NE winds were associated with decreased HR. Decreased SDNN was dominated during NE winds by the incinerator factor, and with SW winds by the metal factor. Metals and mobile source factors also had minor impacts on decreased SDNN with NE winds. Individual elemental components loaded onto these factors generally showed significant associations, although there were some discrepancies.Conclusions: Acute cardiovascular changes in response to ambient PM2.5 exposure can be attributed to specific PM constituents and sources linked with incineration, metal processing, and iron/steel production.

Identifying Cities for Enhanced Fine Particulate Matter Speciation Monitoring

PP-30-018 Background/Aims: Epidemiologic studies have demonstrated adverse human health effects of particulate matter (PM2.5); PM2.5 constituents; and gaseous criteria air pollutants including CO, NO2, SO2, and O3. The current monitoring network covers most major US metropolitan areas. However, most PM constituents collected at Speciation Trend Network monitors are measured only 1 in 3 days or 1 in 6 days, complicating time-series analyses. Since limited resources will support daily monitoring at only a few locations, the major metropolitan areas selected should maximize the pollutant concentration levels and variances, and minimize the covariance between pollutants. Methods: We focused on 48 cities with Speciation Trend Network monitors from 2001 to 2005. We examined the concentration and variability for the gaseous criteria air pollutants and fine particle components, determined their correlations with PM2.5 mass, and evaluated regional and seasonal patterns. We chose PM2.5 species based on their potential to be markers for a particular source including coal combustion, residual oil fly ash, wood smoke, mobile sources, crustal elements, and road salt. Results: Regardless of season or region, markers of coal combustion (S and SO4) were strongly (>0.7)-to-moderately (>0.5) correlated with PM2.5 mass. Strong correlations with wood smoke (K, Br, and Ca) were seen in some cities, usually in the western part of the US during the winter. Elements associated with mobile sources (EC, OC, Zn, and NO3) were at least moderately correlated with PM2.5 in most cities, exhibiting different geographical and seasonal patterns. The correlations between PM2.5 and O3 were negative in the winter and positive in the summer, and showed some regional differences. Finally, markers of residual oil fly ash, crustal sources, and road salt were moderately correlated with PM2.5 in a small percentage of cities. Conclusion: Concentrations, variability, and relationships with PM2.5 differed by pollutant, region, and season. These factors can help identify the metropolitan areas for daily speciation monitoring.

Community-level spatial heterogeneity of chemical constituent levels of fine particulates and implications for epidemiological research

Studies of the health impacts of airborne particulates' chemical constituents typically assume spatial homogeneity and estimate exposure from ambient monitors. However, factors such as local sources may cause spatially heterogeneous pollution levels. This work examines the degree to which constituent levels vary within communities and whether exposure misclassification is introduced by spatial homogeneity assumptions. Analysis considered PM(2.5) elemental carbon (EC), organic carbon matter, ammonium, sulfate, nitrate, silicon, and sodium ion (Na(+)) for the United States, 1999-2007. Pearson correlations and coefficients of divergence were calculated and compared to distances among monitors. Linear modeling related correlations to distance between monitors, long-term constituent levels, and population density. Spatial heterogeneity was present for all constituents, yet lower for ammonium, sulfate, and nitrate. Lower correlations were associated with higher distance between monitors, especially for nitrate and sulfate, and with lower long-term levels, especially for sulfate and Na(+). Analysis of colocated monitors revealed measurement error for all constituents, especially EC and Na(+). Exposure misclassification may be introduced into epidemiological studies of PM(2.5) constituents due to spatial variability, and is affected by constituent type and level. When assessing health effects of PM constituents, new methods are needed for estimating exposure and accounting for exposure error induced by spatial variability.

Particulate Soup: Identifying the Most Toxic Constituents of PM 2.5

Vol. 118, No. 3 NewsOpen AccessParticulate Soup: Identifying the Most Toxic Constituents of PM2.5 Rebecca Clay Haynes Rebecca Clay Haynes Search for more papers by this author Published:1 March 2010https://doi.org/10.1289/ehp.118-a130aAboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Chronic exposure to air pollution has long been linked with cardiopulmonary-related mortality, and ambient fine particulate matter (PM2.5) is often considered a primary cause of this association. Once inhaled, these particles can cause inflammation and oxidative stress. This in turn may result in systemic effects, including the buildup of plaque deposits that can lead to heart attacks and strokes. A new study comparing air pollution exposure with health data gathered over a 5-year span now takes a closer look at which individual constituents of PM2.5 may be most likely responsible for associations between ambient air quality and mortality [EHP118:363–369; Ostro et al.].Ambient PM2.5 contains solid and liquid particles from many sources, particularly from fossil fuel combustion; among other constituents, it contains elemental and organic carbon, sulfates, nitrates, iron, potassium, silicon, and zinc. The National Research Council has highlighted the importance of routinely collecting toxicity data on particle constituents to help refine air quality standards, target control strategies, and enhance the accuracy of health impact assessments.In the current study, the authors used data from the California Teachers Study for 45,000 active and former female public school professionals. The teachers lived within 8 or 30 km of monitors that collected data on PM2.5 between June 2002 and July 2007. The large amount of individual-level data provided by participants allowed researchers to control for risk factors that could possibly confound the analysis. Smoking rates and indoor occupational exposures, for example, were very low in this study cohort, making it easier to identify an independent effect of outdoor air pollution. Air pollution measurements were generally taken twice a week, and information from health questionnaires also helped determine individual exposure.Of 8 constituents studied, organic carbon and sulfates were found to be most strongly associated with all-cause, cardiopulmonary, ischemic heart disease, and pulmonary mortality. Even modest concentrations of these 2 constituents were associated with mortality from all 4 causes. According to the authors, the study provides new information to help focus and streamline regulatory efforts on a variety of sources of PM2.5, including gasoline and diesel fuel, and other combustion activities. They write that the reduction of ambient PM2.5, particularly from fuel combustion, may offer significant public health benefits.PM2.5 contributes to the haze that blankets metropolitan areas.FiguresReferencesRelatedDetails Vol. 118, No. 3 March 2010Metrics About Article Metrics Publication History Originally published1 March 2010Published in print1 March 2010 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

A European aerosol phenomenology – 3: Physical and chemical characteristics of particulate matter from 60 rural, urban, and kerbside sites across Europe

This paper synthesizes data on aerosol (particulate matter, PM) physical and chemical characteristics, which were obtained over the past decade in aerosol research and monitoring activities at more than 60 natural background, rural, near-city, urban, and kerbside sites across Europe. The data include simultaneously measured PM 10 and/or PM 2.5 mass on the one hand, and aerosol particle number concentrations or PM chemistry on the other hand. The aerosol data presented in our previous works ( Van Dingenen et al., 2004; Putaud et al., 2004) were updated and merged to those collected in the framework of the EU supported European Cooperation in the field of Scientific and Technical action COST633 ( Particulate matter: Properties related to health effects). A number of conclusions from our previous studies were confirmed. There is no single ratio between PM 2.5 and PM 10 mass concentrations valid for all sites, although fairly constant ratios ranging from 0.5 to 0.9 are observed at most individual sites. There is no general correlation between PM mass and particle number concentrations, although particle number concentrations increase with PM 2.5 levels at most sites. The main constituents of both PM 10 and PM 2.5 are generally organic matter, sulfate and nitrate. Mineral dust can also be a major constituent of PM 10 at kerbside sites and in Southern Europe. There is a clear decreasing gradient in SO 4 2− and NO 3 − contribution to PM 10 when moving from rural to urban to kerbside sites. In contrast, the total carbon/PM 10 ratio increases from rural to kerbside sites. Some new conclusions were also drawn from this work: the ratio between ultrafine particle and total particle number concentration decreases with PM 2.5 concentration at all sites but one, and significant gradients in PM chemistry are observed when moving from Northwestern, to Southern to Central Europe. Compiling an even larger number of data sets would have further increased the significance of our conclusions, but collecting all the aerosol data sets obtained also through research projects remains a tedious task.

Redox activity of urban quasi-ultrafine particles from primary and secondary sources

To characterize the redox activity profiles of atmospheric aerosols from primary (traffic) and secondary photochemical sources, ambient quasi-ultrafine particles were collected near downtown Los Angeles in two different time periods – morning (6:00–9:00 PDT) and afternoon (11:00–14:00 PDT) in the summer of 2008. Detailed chemical analysis of the collected samples, including water-soluble elements, inorganic ions, organic species and water soluble organic carbon (WSOC) was conducted and redox activity of the samples was measured by two different assays: the dithiothreitol (DTT) and the macrophage reactive oxygen species (ROS) assays. Tracers of secondary photochemical reactions, such as sulfate and organic acids were higher (2.1 ± 0.6 times for sulfate, and up to 3 times for the organic acids) in the afternoon period. WSOC was also elevated by 2.5 ± 0.9 times in the afternoon period due to photo-oxidation of primary particles during atmospheric aging. Redox activity measured by the DTT assay was considerably higher for the samples collected during the afternoon; on the other hand, diurnal trends in the ROS-based activity were not consistent between the morning and afternoon periods. A linear regression between redox activity and various PM chemical constituents showed that the DTT assay was highly correlated with WSOC ( R 2 = 0.80), while ROS activity was associated mostly with water soluble transition metals (Vanadium, Nickel and Cadmium; R 2 > 0.70). The DTT and ROS assays, which are based on the generation of different oxidizing species by chemical PM constituents, provide important information for elucidating the health risks related to PM exposure from different sources. Thus, both primary and secondary particles possess high redox activity; however, photochemical transformations of primary emissions with atmospheric aging enhance the toxicological potency of primary particles in terms of generating oxidative stress and leading to subsequent damage in cells.

Ambient Metals, Elemental Carbon, and Wheeze and Cough in New York City Children through 24 Months of Age

The effects of exposure to specific components of ambient fine particulate matter (PM(2.5)), including metals and elemental carbon (EC), have not been fully characterized in young children. To compare temporal associations among PM(2.5); individual metal constituents of ambient PM(2.5), including nickel (Ni), vanadium (V), and zinc (Zn); and EC and longitudinal reports of respiratory symptoms through 24 months of age. Study participants were selected from the Columbia Center for Children's Environmental Health birth cohort recruited in New York City between 1998 and 2006. Respiratory symptom data were collected by questionnaire every 3 months through 24 months of age. Ambient pollutant data were obtained from state-operated stationary monitoring sites located within the study area. For each subject, 3-month average inverse-distance weighted concentrations of Ni, V, Zn, EC, and PM(2.5) were calculated for each symptom-reporting period based on the questionnaire date and the preceding 3 months. Associations between pollutants and symptoms were characterized using generalized additive mixed effects models, adjusting for sex, ethnicity, environmental tobacco smoke exposure, and calendar time. Increases in ambient Ni and V concentrations were associated significantly with increased probability of wheeze. Increases in EC were associated significantly with cough during the cold/flu season. Total PM(2.5) was not associated with wheeze or cough. These results suggest that exposure to ambient metals and EC from heating oil and/or traffic at levels characteristic of urban environments may be associated with respiratory symptoms among very young children.

Variations of levels and composition of PM 10 and PM 2.5 at an insular site in the Western Mediterranean

The insular suburban site of Castillo de Bellver was selected for the study of the variability of PM levels and composition in the Western Mediterranean Basin (WMB). Mean annual (in 2004) PM 10 and PM 2.5 levels at this site were 29 and 20 µg/m 3, respectively. These levels may be regarded as relatively low when compared with other suburban insular locations in the Eastern Mediterranean Basin (EMB), but they are higher than those recorded at most of the European suburban sites, especially in Northern and Western Europe. Seasonal variability of PM levels at this site is governed by meteorology rather than local emissions, whereas the daily cycles are clearly defined by the anthropogenic emissions, mainly coming from the urban area of Palma de Mallorca and the harbour area of the same city. Concerning the aerosol composition at this site, the main PM constituent is the mineral matter (29% in PM 10 and 16 % in PM 2.5), more than 50% (in PM 10) being attributable to African dust. The amount of secondary inorganic aerosols is also very high (27% in PM 10 and 34% in PM 2.5), with the predominance of fine ammonium sulphate, and in a less proportion fine ammonium nitrate (in winter) and coarse Ca and Na nitrate (with higher importance in summer). The carbonaceous particles, dominantly fine, account for 17% of PM 10 and 25% of PM 2.5. The elemental carbon/organic carbon (EC/OC) ratio reached a mean value of 0.17, similar to those observed at regional background sites in the WMB coast of Spain. The sea spray aerosols (mainly coarse) represented around 10% of PM 10, and only 4% in PM 2.5. Finally, the unaccounted fraction increased from 15% to 20% in PM 2.5, being mostly attributed to water. The concentrations of trace elements in PM 10 and PM 2.5 were usually in the range to those observed in regional background sites in the Iberian Peninsula, with the exception of the typical tracers of road traffic such as Cu, Sb, Zn, Sn and Ba, which presented concentrations in the range of urban sites of Iberia. Other elements such as Cr, Zr, Hf and Co have been identified as the main tracers of the harbour contributions.

Oxidative properties of ambient PM 2.5 and elemental composition: Heterogeneous associations in 19 European cities

We assessed the extent to which constituents of PM 2.5 (transition metals, sodium, chloride) contribute to the ability to generate hydroxyl radicals ( OH) in vitro in PM 2.5 sampled at 20 locations in 19 European centres participating in the European Community Respiratory Health Survey. PM 2.5 samples ( n = 716) were collected on filters over one year and the oxidative activity of particle suspensions obtained from these filters was then assessed by measuring their ability to generate OH in the presence of hydrogen peroxide. Associations between OH formation and the studied PM constituents were heterogeneous. The total explained variance ranged from 85% in Norwich to only 6% in Albacete. Among the 20 centres, 15 showed positive correlations between one or more of the measured transition metals (copper, iron, manganese, lead, vanadium and titanium) and OH formation. In 9 of 20 centres OH formation was negatively associated with chloride, and in 3 centres with sodium. Across 19 European cities, elements which explained the largest variations in OH formation were chloride, iron and sodium.

Population exposure and mortality due to regional background PM in Europe – Long-term simulations of source region and shipping contributions

This paper presents the contribution to population exposure (PE) of regional background fine primary (PPM 2.5) and secondary inorganic (SIA) particulate matter and its impact on mortality in Europe during 1997–2003 calculated with a chemistry transport model. Contributions to concentrations and PE due to emissions from shipping, Western (WEU), Eastern (EEU), and Northern Europe are compared. WEU contributes about 40% to both PPM 2.5 and SIA concentrations, whereas the EEU contribution to PPM 2.5 is much higher (43% of total PPM 2.5) than to SIA (29% of total SIA). The population weighted average concentration (PWC) of PPM 2.5 is a factor of 2.3 higher than average (non-weighted) concentrations, whereas for SIA the PWC is only a factor 1.6 higher. This is due to PPM 2.5 concentrations having larger gradients and being relatively high over densely populated areas, whereas SIA is formed outside populated areas. WEU emissions contribute relatively more than EEU to PWC and mortality due to both PPM 2.5 and SIA in Europe. The number of premature deaths in Europe is estimated to 301 000 per year due to PPM 2.5 exposure and 245 000 due to SIA, despite 3.3 times higher average SIA concentrations. This is due to population weighting and assumed (and uncertain) higher relative risk of mortality for PPM 2.5 components (2.8 times higher RR for PPM 2.5). This study indicates that it might be more efficient, for the health of the European population, to decrease primary PM emissions (especially in WEU) than to decrease precursors of SIA, but more knowledge on the toxicity of different PM constituents is needed before firm conclusions can be drawn.