Ionic composition of PM2.5 at urban sites of northern Greece: secondary inorganic aerosol formation

This study investigates the water-soluble ionic constituents (Na⁺, K⁺, NH₄ ⁺, Ca²⁺, Mg²⁺, Cl^?, NO₃ ^?, SO₄ ^2?) associated to PM_2.5 particle fraction at two urban sites in the city of Thessaloniki, northern Greece, an urban traffic site (UT) and urban background site (UB). Ionic constituents represent a significant fraction of PM_2.5 mass (29.6 at UT and 41.5 % at UB). The contribution of marine aerosol was low (<1.5 %). Secondary inorganic aerosols (SIA) represent a significant fraction of PM_2.5 mass contributing to 26.9?±?12.4 % and 39.2?±?13.2 % at UT and UB sites, respectively. Nitrate and sulfate are fully neutralized by ammonium under the existing conditions. The ionic constituents were evaluated in relation to their spatial and temporal variation, their gaseous precursors, meteorological conditions, local and long-range transport.     

Effect modification of ambient particle mortality by radon: A time series analysis in 108 U.S. cities

Numerous studies have reported a positive association between ambient fine particles and daily mortality, but little is known about the particle properties or environmental factors that may contribute to these effects. This study assessed potential modification of radon on PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm)-associated daily mortality in 108 U.S. cities using a two-stage statistical approach. First, city- and season-specific PM_2.5 mortality risks were estimated using over-dispersed Poisson regression models. These PM_2.5 effect estimates were then regressed against mean city-level residential radon concentrations to estimate overall PM_2.5 effects and potential modification by radon. Radon exposure estimates based on measured short-term basement concentrations and modeled long-term living-area concentrations were both assessed. Exposure to PM_2.5 was associated with total, cardiovascular, and respiratory mortality in both the spring and the fall. In addition, higher mean city-level radon concentrations increased PM_2.5-associated mortality in the spring and fall. For example, a 10 µg/m³ increase in PM_2.5 in the spring at the 10th percentile of city-averaged short-term radon concentrations (21.1 Bq/m³) was associated with a 1.92% increase in total mortality (95% CI: 1.29, 2.55), whereas the same PM_2.5 exposure at the 90th radon percentile (234.2 Bq/m³) was associated with a 3.73% increase in total mortality (95% CI: 2.87, 4.59). Results were robust to adjustment for spatial confounders, including average planetary boundary height, population age, percent poverty and tobacco use. While additional research is necessary, this study suggests that radon enhances PM_2.5 mortality. This is of significant regulatory importance, as effective regulation should consider the increased risk for particle mortality in cities with higher radon levels.

Implications: In this large national study, city-averaged indoor radon concentration was a significant effect modifier of PM_2.5-associated total, cardiovascular, and respiratory mortality risk in the spring and fall. These results suggest that radon may enhance PM_2.5-associated mortality. In addition, local radon concentrations partially explain the significant variability in PM_2.5 effect estimates across U.S. cities, noted in this and previous studies. Although the concept of PM as a vector for radon progeny is feasible, additional research is needed on the noncancer health effects of radon and its potential interaction with PM. Future air quality regulations may need to consider the increased risk for particle mortality in cities with higher radon levels.     

Association between particulate matter air pollution and cardiovascular disease mortality in Lanzhou,China

Ambient particulate matter (PM) pollution has been linked to elevated mortality, especially from cardiovascular diseases. However, evidence on the effects of particulate matter pollution on cardiovascular mortality is still limited in Lanzhou, China. This research aimed to examine the associations of daily mean concentrations of ambient air pollutants (PM_2.5, PM_C, and PM₁₀) and cardiovascular mortality due to overall and cause-specific diseases in Lanzhou. Data representing daily cardiovascular mortality rates, meteorological factors (daily average temperature, daily average humidity, and atmospheric pressure), and air pollutants (PM_2.5, PM₁₀, SO₂, NO₂) were collected from January 1, 2014, to December 31, 2017, in Lanzhou. A quasi-Poisson regression model combined with a distributed lag non-linear model (DLNM) was used to estimate the associations. Stratified analyses were also performed by different cause-specific diseases, including cerebrovascular disease (CD), ischemic heart disease (IHD), heart rhythm disturbances (HRD), and heart failure (HF). The results showed that elevated concentration of PM_2.5, PM_C, and PM₁₀ had different effects on mortality of different cardiovascular diseases. Only cerebrovascular disease showed a significant positive association with elevated PM_2.5. Positive associations were identified between PM_C and daily mortality rates from total cardiovascular diseases, cerebrovascular diseases, and ischemic heart diseases. Besides, increased concentration of PM₁₀ was correlated with increased death of cerebrovascular diseases and ischemic heart diseases. For cerebrovascular disease, each 10 μg/m³ increase in PM_2.5 at lag4 was associated with increments of 1.22% (95% CI 0.11–2.35%). The largest significant effects for PM_C on cardiovascular diseases and ischemic heart diseases were both observed at lag0, and a 10 μg/m³ increment in concentration of PM_C was associated with 0.47% (95% CI 0.06–0.88%) and 0.85% (95% CI 0.18–1.52%) increases in cardiovascular mortality and ischemic heart diseases. In addition, it exhibited a lag effect on cerebrovascular mortality as well, which was most significant at lag6d, and an increase of 10 μg/m³ in PM_C was associated with a 0.76% (95% CI 0.16–1.37%) increase in cerebrovascular mortality. The estimates of percentage change in daily mortality rates per 10 μg/m³ increase in PM₁₀ were 0.52% (95% CI 0.05–1.02%) for cerebrovascular disease at lag6 and 0.53% (95% CI 0.01–1.05%) for ischemic heart disease at lag0, respectively. Our study suggests that elevated concentration of atmospheric PM (PM_2.5, PM_C, and PM₁₀) in Lanzhou is associated with increased mortality of cardiovascular diseases and that the health effect of elevated concentration of PM_2.5 is more significant than that of PM_C and PM₁₀.

     

Particulate Air Pollution and Health Effects for Cardiovascular and Respiratory Causes in Temuco,Chile: A Wood-Smoke-Polluted Urban Area

Abstract

Temuco is one of the most highly wood-smoke-polluted cities in the world. Its population in 2004 was 340,000 inhabitants with 1587 annual deaths, of which 24% were due to cardiovascular and 11% to respiratory causes. For hospital admissions, cardiovascular diseases represented 6% and respiratory diseases 13%. Emergency room visits for acute respiratory infections represented 28%. The objective of the study presented here was to determine the relationship between air pollution from particulate matter less than or equal to 10 µm in aerodynamic diameter (PM₁₀; mostly PM_2.5, or particulate matter <2.5 µm in aerodynamic diameter) and health effects measured as the daily number of deaths, hospital admissions, and emergency room visits for cardiovascular, respiratory, and acute respiratory infection (ARI) diseases. The Air Pollution Health Effects European Approach (APHEA2) protocol was followed, and a multivariate Poisson regression model was fitted, controlling for trend, seasonality, and confounders for Temuco during 1998–2006. The results show that PM₁₀ had a significant association with daily mortality and morbidity, with the elderly (population >65 yr of age) being the group that presented the greatest risk. The relative risk for respiratory causes, with an increase of 100 µg/m³ of PM_10, was 1.163 with a 95% confidence interval (CI) of 1.057–1.279 for mortality, 1.137 (CI 1.096–1.178) for hospital admissions, and 1.162 for ARI (CI 1.144–1.181). There is evidence in Temuco of positive relationships between ambient particulate levels and mortality, hospital admissions, and ARI for cardiovascular and respiratory diseases. These results are consistent with those of comparable studies in other similar cities where wood smoke is the most important air pollution problem.     

The characterization of water-soluble inorganic ions in PM2.5 during a winter period in Xi'an,China

The characteristics of water-soluble inorganic ions (WSIIs) during a winter period in a suburb of Xi'an, China, were investigated. Our results show that the total mass concentration of the dominant WSIIs (8) was 91.27 µg m^–3, accounting for 50.1% of the total mass concentration of PM_2.5 (particulates with a size of 2.5 µm or less). Secondary inorganic aerosols (SO₄^2?, NO₃^? and NH₄⁺) were the most abundant ions, accounting for up to 95.12% of the total ions. By using the anion and cation equivalence ratio method, PM_2.5 was shown to have weak alkalinity, and the chemical forms of WSIIs were mainly (NH₄)₂SO₄ and NH₄NO₃. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) suggested that larger proportions of SO₄^2? and NO₃^? were formed by gas-phase SO₂ and NO₂ in the sampling site. Ratio analysis also indicated that anthropogenic sources significantly contributed to WSII pollution. Among the anthropogenic sources, fixed pollution sources were found to be dominant over mobile sources.     

Chemical characteristics and source apportionment of PM<Subscript>2.5</Subscript> using PCA/APCS,UNMIX, and PMF at an urban site of Delhi,India

The present study investigated the comprehensive chemical composition [organic carbon (OC), elemental carbon (EC), water-soluble inorganic ionic components (WSICs), and major & trace elements] of particulate matter (PM_2.5) and scrutinized their emission sources for urban region of Delhi. The 135 PM_2.5 samples were collected from January 2013 to December 2014 and analyzed for chemical constituents for source apportionment study. The average concentration of PM_2.5 was recorded as 121.9 ± 93.2 μg m^?3 (range 25.1–429.8 μg m^?3), whereas the total concentration of trace elements (Na, Ca, Mg, Al, S, Cl, K, Cr, Si, Ti, As, Br, Pb, Fe, Zn, and Mn) was accounted for ～17% of PM_2.5. Strong seasonal variation was observed in PM_2.5 mass concentration and its chemical composition with maxima during winter and minima during monsoon seasons. The chemical composition of the PM_2.5 was reconstructed using IMPROVE equation, which was observed to be in good agreement with the gravimetric mass. Source apportionment of PM_2.5 was carried out using the following three different receptor models: principal component analysis with absolute principal component scores (PCA/APCS), which identified five major sources; UNMIX which identified four major sources; and positive matrix factorization (PMF), which explored seven major sources. The applied models were able to identify the major sources contributing to the PM_2.5 and re-confirmed that secondary aerosols (SAs), soil/road dust (SD), vehicular emissions (VEs), biomass burning (BB), fossil fuel combustion (FFC), and industrial emission (IE) were dominant contributors to PM_2.5 in Delhi. The influences of local and regional sources were also explored using 5-day backward air mass trajectory analysis, cluster analysis, and potential source contribution function (PSCF). Cluster and PSCF results indicated that local as well as long-transported PM_2.5 from the north-west India and Pakistan were mostly pertinent.     

Physicochemical variations in atmospheric aerosols recorded at sea onboard the Atlantic–Mediterranean 2008 Scholar Ship cruise (Part I): Particle mass concentrations,size ratios,and main chemical components

We report on ambient atmospheric aerosols present at sea during the Atlantic–Mediterranean voyage of Oceanic II (The Scholar Ship) in spring 2008. A record was obtained of hourly PM₁₀, PM_2.5, and PM₁ particle size fraction concentrations and 24-h filter samples for chemical analysis which allowed for comparison between levels of crustal particles, sea spray, total carbon, and secondary inorganic aerosols. On-board monitoring was continuous from the equatorial Atlantic to the Straits of Gibraltar, across the Mediterranean to Istanbul, and back via Lisbon to the English Channel. Initially clean air in the open Atlantic registered PM₁₀ levels <10 μg m^?3 but became progressively polluted by increasingly coarse PM as the ship approached land. Away from major port cities, the main sources of atmospheric contamination identified were dust intrusions from North Africa (NAF), smoke plumes from biomass burning in sub-Saharan Africa and Russia, industrial sulphate clouds and other regional pollution sources transported from Europe, sea spray during rough seas, and plumes emanating from islands. Under dry NAF intrusions PM₁₀ daily mean levels averaged 40–60 μg m^?3 (30–40 μg m^?3 PM_2.5; c. 20 μg m^?3 PM₁), peaking briefly to >120 μg m^?3 (hourly mean) when the ship passed through curtains of higher dust concentrations amassed at the frontal edge of the dust cloud. PM₁/PM₁₀ ratios ranged from very low during desert dust intrusions (0.3–0.4) to very high during anthropogenic pollution plume events (0.8–1).     

Effect of PM2.5 chemical constituents on atmospheric visibility impairment

PM_2.5 sampling was conducted at a curbside location in Delhi city for summer and winter seasons, to evaluate the effect of PM_2.5 and its chemical components on the visibility impairment. The PM_2.5 concentrations were observed to be higher than the National Ambient Air Quality Standards (NAAQS), indicating poor air quality. The chemical constituents of PM_2.5 (the water-soluble ionic species SO₄^2-, NO₃^?, Cl^?, and NH₄⁺, and carbonaceous species: organic carbon, elemental carbon) were analyzed to study their impact on visibility impairment by reconstructing the light extinction coefficient, b_ext. The visibility was found to be negatively correlated with PM_2.5 and its components. The reconstructed b_ext showed that organic matter was the largest contributor to b_ext in both the seasons which may be attributed to combustion sources. In summer season, it was followed by elemental carbon and ammonium sulfate; however, in winter, major contributions were from ammonium nitrate and elemental carbon. Higher elemental carbon in both seasons may be attributed to traffic sources, while lower concentrations of nitrate during summer, may be attributed to volatility because of higher atmospheric temperatures.

Implications: The chemical constituents of PM_2.5 that majorly effect the visibility impairment are organic matter and elemental carbon, both of which are products of combustion processes. Secondary formations that lead to ammonium sulfate and ammonium nitrate production also impair the visibility.     

The Impact of Particulate Matter on Daily Mortality in Bangkok,Thailand

ABSTRACT

Several studies conducted in U.S. cities report an association between acute exposures to particulate matter (PM), usually measured as PM_10, and mortality. Evidence of high concentrations of PM₁₀ in Eastern Europe and in large metropolitan areas outside of the United States, such as Mexico City and Bangkok, underscores the need to determine whether these same associations occur outside of the United States. In addition, conducting studies of mortality and air pollution in regions that have distinctly different seasonal patterns than those of the United States provides an effective opportunity to assess the potentially confounding aspects of seasonality. Over the last few years, daily measures of ambient PM₁₀ have been collected in Bangkok, a tropical city of over 6 million people. In this metropolitan area, PM₁₀ consists largely of fine particles generated from diesel- and gasoline-powered automobiles, and from two-stroke motorcycle engines. Our analysis involved the examination of the relationship between PM₁₀ and daily mortality for 1992 through 1995. In addition to counts of daily natural mortality (total mortality net of accidents, homicides, and suicides), the data were compiled to assess both cardiovascular and respiratory mortality, and natural mortality by age group. A multivariate Poisson regression model was used to explain daily mortality while controlling for several covariates including temperature, humidity, day of the week, season, and time. The analysis indicated a statistically significant association between PM10 and all of the alternative measures of mortality. The results suggest a 10-µg/m³ change in daily PM₁₀ is associated with a 1–2% increase in natural mortality, a 1–2% increase in cardiovascular mortality, and a 3–6% increase in respiratory mortality. These relative risks are generally consistent with or greater than those reported in most studies undertaken in the United States.     

Source apportionment of ambient PM2.5 at five spanish centres of the european community respiratory health survey (ECRHS II)

Fine particulate matter (PM_2.5) was sampled at 5 Spanish locations during the European Community Respiratory Health Survey II (ECRHS II). In an attempt to identify and quantify PM_2.5 sources, source contribution analysis by principal component analysis (PCA) was performed on five datasets containing elemental composition of PM_2.5 analysed by ED-XRF. A total of 4–5 factors were identified at each site, three of them being common to all sites (interpreted as traffic, mineral and secondary aerosols) whereas industrial sources were site-specific. Sea-salt was identified as independent source at all coastal locations except for Barcelona (where it was clustered with secondary aerosols). Despite their typically dominant coarse grain-size distribution, mineral and marine aerosols were clearly observed in PM_2.5. Multi-linear regression analysis (MLRA) was applied to the data, showing that traffic was the main source of PM_2.5 at the five sites (39–53% of PM_2.5, 5.1–12.0 μg m⁻³), while regional-scale secondary aerosols accounted for 14–34% of PM_2.5 (2.6–4.5 μg m⁻³), mineral matter for 13–31% (2.4–4.6 μg m⁻³) and sea-salt made up 3–7% of the PM_2.5 mass (0.4–1.3 μg m⁻³). Consequently, despite regional and climatic variability throughout Spain, the same four main PM_2.5 emission sources were identified at all the study sites and the differences between the relative contributions of each of these sources varied at most 20%. This would corroborate PM_2.5 as a useful parameter for health studies and environmental policy-making, owing to the fact that it is not as subject to the influence of micro-sitting as other parameters such as PM₁₀. African dust inputs were observed in the mineral source, adding on average 4–11 μg m⁻³ to the PM_2.5 daily mean during dust outbreaks. On average, levels of Al, Si, Ti and Fe during African episodes were higher by a factor of 2–8 with respect to non-African days, whereas levels of local pollutants (absorption coefficient, S, Pb, Cl) showed smaller variations (factor of 0.5–2).     

Characteristics of the major chemical constituents of PM2.5 and smog events in Seoul,Korea in 2003 and 2004

One hundred ninety-five chemically speciated samples were collected from March 2003 to February 2005 in the Seoul Metropolitan area to investigate the characteristics of the major components in PM_2.5 and to characterize the chemical variations between smog and non-smog events. The annual average PM_2.5 concentration was 43 μg m⁻³ that is almost three times higher than the US NAAQS annual PM_2.5 standard of 15 μg m⁻³. During this sampling period, smog and yellow sand events were observed on 27 and 10 days, respectively. The PM_2.5 concentrations and its constituents during smog events were about two–three times higher than those during non-smog and yellow sand events. In particular, the mass fractions of secondary aerosols such as sulfate, nitrate, and ammonium during the smog events were higher than those of the other constituents. The mean concentration and mass fraction of secondary organic carbon (SOC) were highest during the winter smog events. Sulfate, nitrate and SOC that can have long residence times were important species during the smog events suggesting that regional scale sources rather than local sources were important. Five-day backward air trajectory analysis showed that the air parcels during smog events passed through the major industrial areas in China more often than those during non-smog events.     

Temporal patterns in daily measurements of inorganic and organic speciated PM2.5 in Denver

Airborne particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) has been linked to a wide range of adverse health effects and as a result is currently regulated by the U.S. Environmental Protection Agency. PM_2.5 originates from a multitude of sources and has heterogeneous physical and chemical characteristics. These features complicate the link between PM_2.5 emission sources, ambient concentrations and health effects. The goal of the Denver Aerosol Sources and Health (DASH) study is to investigate associations between sources and health using daily measurements of speciated PM_2.5 in Denver.The datxa set being collected for the DASH study will be the longest daily speciated PM_2.5 data set of its kind covering 5.5 years of daily inorganic and organic speciated measurements. As of 2008, 4.5 years of bulk measurements (mass, inorganic ions and total carbon) and 1.5 years of organic molecular marker measurements have been completed. Several techniques were used to reveal long-term and short-term temporal patterns in the bulk species and the organic molecular marker species. All species showed a strong annual periodicity, but their monthly and seasonal behavior varied substantially. Weekly periodicities appear in many compound classes with the most significant weekday/weekend effect observed for elemental carbon, cholestanes, hopanes, select polycyclic aromatic hydrocarbons (PAHs), heavy n-alkanoic acids and methoxyphenols. Many of the observed patterns can be explained by meteorology or anthropogenic activity patterns while others do not appear to have such obvious explanations. Similarities and differences in these findings compared to those reported from other cities are highlighted.     

Determination of Source Contributions to Ambient PM2.5 in Kaohsiung,Taiwan, Using a Receptor Model

ABSTRACT

Ambient particulates of PM_2.5 were sampled at three sites in Kaohsiung, Taiwan, during February and March 1999. In addition, resuspended PM_2.5 collected from traffic tunnels, paved roads, fly ash of a municipal solid waste (MSW) incinerator, and seawater was obtained. All the samples were analyzed for twenty constituents, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metallic elements. In conjunction with local source profiles and the source profiles in the model library SPECIATE EPA, the receptor model based on chemical mass balance (CMB) was then applied to determine the source contributions to ambient PM_2.5.

The mean concentration of ambient PM_2.5 was 42.6953.68 μj.g/m³ for the sampling period. The abundant species in ambient PM_2.5 in the mass fraction for three sites were OC (12.7-14.2%), SO₄ ^2- (12.8-15.1%), NO₃ ^- (8.110.3%), NH₄+ (6.7-7.5%), and EC (5.3-8.5%). Results of CMB modeling show that major pollution sources for ambient PM_2.5 are traffic exhaust (18-54%), secondary aerosols (30-41% from SO₄ ^2- and NO₃ ^-), and outdoor burning of agriculture wastes (13-17%).     

Rapid Nitrate Loss from PM10 Filters

The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM_2.5 in its atmosphere since 2003. The contribution of possible sources of primary PM_2.5 and its precursors is not known. In this paper we present the results of analyzing the chemical composition of sixty 24-hr samples of PM_2.5 to determine possible sources of PM_2.5 in the MMA. The samples were collected at the northeast and southeast of the MMA between November 22 and December 12, 2007, using low-volume devices. Teflon and quartz filters were used to collect the samples. The concentrations of 16 airborne trace elements were determined using x-ray fluorescence (XRF). Anions and cations were determined using ion chromatography. Organic carbon (OC) and elemental carbon (EC) were determined by thermal optical analysis. The results show that Ca had the maximum mean concentration of all elements studied, followed by S. Enrichment factors above 50 were calculated for S, Cl, Cu, Zn, Br, and Pb. This indicates that these elements may come from anthropogenic sources. Overall, the major average components of PM_2.5 were OC (41.7%), SO₄ ^2? (22.9%), EC (7.4%), crustal material (11.4%), and NO₃ ^? (12.6%), which altogether accounted for 96% of the mass. Statistically, we did not find any difference in SO₄ ^2? concentrations between the two sites. The fraction of secondary organic carbon was between 24% and 34%. The results of the factor analysis performed over 10 metals and OC and EC show that there are three main sources of PM_2.5: crustal material and vehicle exhaust; industrial activity; and fuel oil burning. The results show that SO₄ ^2?, OC, and crustal material are important components of PM_2.5 in MMA. Further work is necessary to evaluate the proportion of secondary inorganic and organic aerosol in order to have a better understanding of the sources and precursors of aerosols in the MMA.

Implications: The MMA has become one of the most air polluted areas in Mexico. High levels of PM_2.5 have been measured and effective actions need to be taken to reduce air pollution and the associated health risks. Several sources of primary PM_2.5 and precursors of secondary particles exist in the MMA. This study provides valuable information for the local environmental authorities to identify possible sources of primary PM_2.5 and its precursors. The effectiveness of the actions taken to improve air quality will lead to health benefits for the population, reducing their associated costs.     

Characteristics of water-soluble inorganic ions in PM2.5 and PM2.5–10 in the coastal urban agglomeration along the Western Taiwan Strait Region,China

PM_2.5 and PM_2.5–10 aerosol samples were collected in four seasons during November 2010, January, April, and August 2011 at 13 urban/suburban sites and one background site in Western Taiwan Straits Region (WTSR), which is the coastal area with rapid urbanization, high population density, and deteriorating air quality. The 10 days average PM_2.5 concentrations were 92.92, 51.96, 74.48, and 89.69 μg/m³ in spring, summer, autumn, and winter, respectively, exceeding the Chinese ambient air quality standard for annual average value of PM_2.5 (grade II, 35 μg/m³). Temporal distribution of water-soluble inorganic ions (WSIIs) in PM_2.5 was coincident with PM_2.5 mass concentrations, showing highest in spring, lowest in summer, and middle in autumn and winter. WSIIs took considerable proportion (42.2～50.1 %) in PM_2.5 and PM_2.5–10. Generally, urban/suburban sites had obviously suffered severer pollution of fine particles compared with the background site. The WSIIs concentrations and characteristics were closely related to the local anthropogenic activities and natural environment, urban sites in cities with higher urbanization level, or sites with weaker diffuse condition suffered severer WSIIs pollution. Fossil fuel combustion, traffic emissions, crustal/soil dust, municipal constructions, and sea salt and biomass burnings were the major potential sources of WSIIs in PM_2.5 in WTSR according to the result of principal component analysis.     

Retrospective assessment of air quality management practices in Taiwan

In 1995, Taiwan's Environmental Protection Administration (EPA/TW) instituted a policy of levying emission taxes on polluters in order to combat the rampant national issue of pollution. Since that time, pollution control strategies, tightening exhaust emission standards for industry, improvements in fuel quality, and new stricter vehicle emission standards, etc., have been implemented. This study evaluates the effectiveness of these measures and examines the improvement of Taiwan's air quality. In this paper, we conduct a detailed analysis of change in the concentrations of pollutants (SO₂, NO_x and particulate matter [PM]) between two three-year periods (from 1996 to1998 and from 2000 to 2002). The pollution levels were generally lower in the latter period. Concentrations at 14 EPA/TW stations in central Taiwan were simulated and source apportionment analyses in three of Central Taiwan's largest cities were conducted using a trajectory transfer-coefficient air quality model. Correlation coefficients (r) between simulations and observations for the monthly means of the concentrations of SO₂, NO_x, PM_2.5 and PM₁₀ during the study periods at the 14 stations are 0.56, 0.63, 0.70 and 0.31, respectively. The sulfur control policy greatly reduced SO₂ concentration island-wide, a stringent emission standard put into place for gasoline vehicles reduced NO_x concentration along highways, and an emissions tax placed on construction sites, as well as a regular program for road-dust sweeping, reduced primary particulate matter. Among all of the pollution abatement policies implemented, the most effective method for reducing PM_2.5 concentrations in the three largest cities involved the reduction of fine ammonium sulfate aerosols from point sources (56–63% of net PM_2.5 reduction). The next largest reduction was attributed to a diminishment in primary PM_2.5 emanating from point sources (27–56% of net PM_2.5 reduction). Secondary particulate matter, especially sulfate, was reduced from distances up to 150 km leeward of major pollution point sources such as Taichung Power Plant.     

The acute effects of fine particles on respiratory mortality and morbidity in Beijing, 2004–2009

Recent epidemiological and toxicological studies have shown associations between particulate matter and human health. However, the estimates of adverse health effects are inconsistent across many countries and areas. The stratification and interaction models were employed within the context of the generalized additive Poisson regression equation to examine the acute effects of fine particles on respiratory health and to explore the possible joint modification of temperature, humidity, and season in Beijing, China, for the period 2004–2009. The results revealed that the respiratory health damage threshold of the PM_2.5 concentration was mainly within the range of 20–60 μg/m³, and the adverse effect of excessively high PM_2.5 concentration maintained a stable level. In the most serious case, an increase of 10 μg/m³ PM_2.5 results in an elevation of 4.60 % (95 % CI 3.84–4.60 %) and 4.48 % (95 % CI 3.53–5.41 %) with a lag of 3 days, values far higher than the average level of 0.69 % (95 % CI 0.54–0.85 %) and 1.32 % (95 % CI 1.02–1.61 %) for respiratory mortality and morbidity, respectively. There were strong seasonal patterns of adverse effects with the seasonal variation of temperature and humidity. The growth rates of respiratory mortality and morbidity were highest in winter. And, they increased 1.4 and 1.8 times in winter, greater than in the full year as PM_2.5 increased 10 μg/m³.     

Infant Mortality and Air Pollution: A Comprehensive Analysis of U.S. Data for 1990

ABSTRACT

This paper uses U.S. linked birth and death records to explore associations between infant mortality and environmental factors, based on spatial relationships. The analysis considers a range of infant mortality end points, regression models, and environmental and socioeconomic variables. The basic analysis involves logistic regression modeling of individuals; the cohort comprises all infants born in the United States in 1990 for whom the required data are available from the matched birth and death records. These individual data include sex, race, month of birth, and birth weight of the infant, and personal data on the mother, including age, adequacy of prenatal care, and smoking and education in most instances. Ecological variables from Census and other sources are matched on the county of usual residence and include ambient air quality, elevation above sea level, climate, number of physicians per capita, median income, racial and ethnic distribution, unemployment, and population density. The air quality variables considered were 1990 annual averages of PM₁₀, CO, SO₂, SO₄ ^2-, and “non-sulfate PM₁₀” (NSPM₁₀—obtained by subtracting the estimated SO₄ ^2-mass from PM₁₀). Because all variables were not available for all counties (especially maternal smoking), it was necessary to consider various subsets of the total cohort.

We examined all infant deaths and deaths by age (neonatal and postneonatal), by birth weight (normal and low [<2500 g]), and by specific causes within these categories. Special attention was given to sudden infant death syndrome (SIDS). For comparable modeling assumptions, the results for PM₁₀ agreed with previously published estimates; however, the associations with PM₁₀ were not specific to probable exposures or causes of death and were not robust to changes in the model and/or the locations considered. Significant negative mortality associations were found for SO₄ ^2-. There was no indication of a role for outdoor PM_2.5, but possible contributions from indoor air pollution sources cannot be ruled out, given higher SIDS rates in winter, in the north and west, and outside of large cities.     

Sources and characteristics of carbonaceous aerosols at Agra “World heritage site” and Delhi “capital city of India”

Agra, one of the oldest cities “World Heritage site”, and Delhi, the capital city of India are both located in the border of Indo-Gangetic Plains (IGP) and heavily loaded with atmospheric aerosols due to tourist place, anthropogenic activities, and its topography, respectively. Therefore, there is need for monitoring of atmospheric aerosols to perceive the scenario and effects of particles over northern part of India. The present study was carried out at Agra (AGR) as well as Delhi (DEL) during winter period from November 2011 to February 2012 of fine particulate (PM_2.5: d?<?2.5 μm) as well as associated carbonaceous aerosols. PM_2.5 was collected at both places using medium volume air sampler (offline measurement) and analyzed for organic carbon (OC) and elemental carbon (EC). Also, simultaneously, black carbon (BC) was measured (online) at DEL. The average mass concentration of PM_2.5 was 165.42?±?119.46 μg m^?3 at AGR while at DEL it was 211.67?±?41.94 μg m^?3 which is ~27 % higher at DEL than AGR whereas the BC mass concentration was 10.60 μg m^?3. The PM_2.5 was substantially higher than the annual standard stipulated by central pollution control board and United States Environmental Protection Agency standards. The average concentrations of OC and EC were 69.96?±?34.42 and 9.53?±?7.27 μm m^?3, respectively. Total carbon (TC) was 79.01?±?38.98 μg m^?3 at AGR, while it was 50.11?±?11.93 (OC), 10.67?±?3.56 μg m^?3 (EC), and 60.78?±?14.56 μg m^?3 (TC) at DEL. The OC/EC ratio was 13.75 at (AGR) and 5.45 at (DEL). The higher OC/EC ratio at Agra indicates that the formation of secondary organic aerosol which emitted from variable primary sources. Significant correlation between PM_2.5 and its carbonaceous species were observed indicating similarity in sources at both sites. The average concentrations of secondary organic carbon (SOC) and primary organic carbon (POC) at AGR were 48.16 and 26.52 μg m^?3 while at DEL it was 38.78 and 27.55 μg m^?3, respectively. In the case of POC, similar concentrations were observed at both places but in the case of SOC higher over AGR by 24 in comparison to DEL, it is due to the high concentration of OC over AGR. Secondary organic aerosol (SOA) was 42 % higher at AGR than DEL which confirms the formation of secondary aerosol at AGR due to rural environment with higher concentrations of coarse mode particles. The SOA contribution in PM_2.5 was also estimated and was ~32 and 12 % at AGR and DEL respectively. Being high loading of fine particles along with carbonaceous aerosol, it is suggested to take necessary and immediate action in mitigation of the emission of carbonaceous aerosol in the northern part of India.     

Assessing the Relationship between Personal Particulate and Gaseous Exposures of Senior Citizens Living in Baltimore,MD

ABSTRACT

We conducted a multi-pollutant exposure study in Baltimore, MD, in which 15 non-smoking older adult subjects (>64 years old) wore a multi-pollutant sampler for 12 days during the summer of 1998 and the winter of 1999. The sampler measured simultaneous 24-hr integrated personal exposures to PM₂₅, PM₁₀, SO₄ ^2-, O₃, NO₂, SO₂, and exhaust-related VOCs.

Results of this study showed that longitudinal associations between ambient PM_2.5 concentrations and corresponding personal exposures tended to be high in the summer (median Spearman's r = 0.74) and low in the winter (median Spearman's r = 0.25). Indoor ventilation was an important determinant of personal PM_2.5 exposures and resulting personal-ambient associations. Associations between personal PM₂₅ exposures and corresponding ambient concentrations were strongest for well-ventilated indoor environments and decreased with ventilation. This decrease was attributed to the increasing influence of indoor PM_{2 5} sources. Evidence for this was provided by SO₄ ^2-measurements, which can be thought of as a tracer for ambient PM₂₅. For SO₄ ^2-, personal-ambient associations were strong even in poorly ventilated indoor environments, suggesting that personal exposures to PM_2.5 of ambient origin are strongly associated with corresponding ambient concentrations. The results also indicated that the contribution of indoor PM_2.5 sources to personal PM_2.5 exposures was lowest when individuals spent the majority of their time in well-ventilated indoor environments.

Results also indicate that the potential for confounding by PM_2.5 co-pollutants is limited, despite significant correlations among ambient pollutant concentrations. In contrast to ambient concentrations, PM_2.5 exposures were not significantly correlated with personal exposures to PM_2.5-10, PM_2.5 of non-ambient origin, O₃, NO₂, and SO₂. Since a confounder must be associated with the exposure of interest, these results provide evidence that the effects observed in the PM_2.5 epidemiologic studies are unlikely to be due to confounding by the PM_2.5 co-pollutants measured in this study.