Showing papers on "Particulates published in 2010"

Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application

Abstract: BackgroundEpidemiologic and health impact studies of fine particulate matter with diameter < 2.5 μm (PM2.5) are limited by the lack of monitoring data, especially in developing countries. Satellite...

An estimate of the global burden of anthropogenic ozone and fine particulate matter on premature human mortality using atmospheric modeling.

Abstract: BackgroundGround-level concentrations of ozone (O3) and fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM2.5)] have increased since preindustrial times in urban and rural regions and ar...

Particulate matter-induced health effects: who is susceptible?

Abstract: BackgroundEpidemiological, controlled human exposure, and toxicological studies have demonstrated a variety of health effects in response to particulate matter (PM) exposure with some of these stud...

Commuters’ Exposure to Particulate Matter Air Pollution Is Affected by Mode of Transport, Fuel Type, and Route

Abstract: BackgroundCommuters are exposed to high concentrations of air pollutants, but little quantitative information is currently available on differences in exposure between different modes of transport,...

Cardiovascular Effects of Ambient Particulate Air Pollution Exposure

Abstract: An association between high levels of air pollutants and human disease has been known for more than half a century. Air pollution is composed of a heterogeneous mixture of compounds including ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), liquids, and particulate matter (PM). Substantial epidemiological evidence implicates air pollution, particularly PM, as a major risk factor with serious consequences on human health.1–3 Of particular interest in PM are the particles that are ≤10 μm in diameter (PM10) because they are the PM that ultimately enters the lungs.4 PM is further divided into coarse (10 to 2.5 μm; PM10–2.5), fine (<2.5 μm; PM2.5), and ultrafine (<0.1 μm; PM0.1) particles.1 These particles are composed of solid and liquid components that originate from vehicle exhaust, road dust, smokestacks, forest fires, windblown soil, volcanic emissions, and sea spray. Particle size, surface area, and chemical composition determine the health risk posed by PM. Particulate and gaseous pollutants coexist in the air and may induce adverse health effects, whereas compelling data implicate PM as a major perpetrator of various types of human disease. PM rarely exists by itself within the ambient environment because gaseous and semivolatile/volatile compounds (ie, aldehydes and polycyclic aromatic hydrocarbons) are constantly changing and interacting. Many of these vapor-phase compounds attach to the surface of PM and/or by themselves form secondary aerosol particles. Because of their small size, PM2.5 and PM0.1 are inhaled deeply into the lungs, with a portion depositing in the alveoli and entering the pulmonary circulation and presumably the systemic circulation. The adverse effects of PM on the cardiovascular system have been established in a series of major epidemiological and observational studies.5–9 Although life expectancy has been improved significantly since air pollution levels …

Persistent organic pollutants

Abstract: The Task Force on Hemispheric Transport of Air Pollution (TF HTAP) was created by the Convention on Long-range Transboundary Air Pollution (LRTAP Convention) in December 2004 to improve the understanding of the intercontinental transport of air pollutants across the Northern Hemisphere. This multivolume assessment produced by the TF HTAP reviews the state-of-the-science with respect to the intercontinental transport of ozone (O3), particulate matter (PM), mercury (Hg), and persistent organic pollutants (POPs).

Heterogeneous photocatalytic cleavage of water

Abstract: The photocatalytic cleavage of water has become of increasing interest in recent years for the manufacture of hydrogen, a clean and renewable energy carrier. The production of H2 using heterogeneous photocatalysts is reviewed in this feature article. Particulate or electrode heterogeneous catalysts under light irradiation can successively reduce H+ into H2 and oxidize water to produce O2, achieving cleavage of water (H2O → H2 + 1/2O2).

To What Extent Can Biogenic SOA be Controlled

Abstract: The implicit assumption that biogenic secondary organic aerosol (SOA) is natural and can not be controlled hinders effective air quality management. Anthropogenic pollution facilitates transformation of naturally emitted volatile organic compounds (VOCs) to the particle phase, enhancing the ambient concentrations of biogenic secondary organic aerosol (SOA). It is therefore conceivable that some portion of ambient biogenic SOA can be removed by controlling emissions of anthropogenic pollutants. Direct measurement of the controllable fraction of biogenic SOA is not possible, but can be estimated through 3-dimensional photochemical air quality modeling. To examine this in detail, 22 CMAQ model simulations were conducted over the continental U.S. (August 15 to September 4, 2003). The relative contributions of five emitted pollution classes (i.e., NOx, NH3, SOx, reactive non methane carbon (RNMC) and primary carbonaceous particulate matter (PCM)) on biogenic SOA were estimated by removing anthropogenic emissio...

Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

Abstract: . We use a 3-D global chemical transport model (GEOS-Chem) to interpret aircraft observations of nitrate and sulfate partitioning in transpacific dust plumes during the INTEX-B campaign of April–May 2006. The model includes explicit transport of size-resolved mineral dust and its alkalinity, nitrate, and sulfate content. The observations show that particulate nitrate is primarily associated with dust, sulfate is primarily associated with ammonium, and Asian dust remains alkaline across the Pacific. This can be reproduced in the model by using a reactive uptake coefficient for HNO3 on dust (γ(HNO3) ~10−3) much lower than commonly assumed in models and possibly reflecting limitation of uptake by dust dissolution. The model overestimates gas-phase HNO3 by a factor of 2–3, typical of previous model studies; we show that this cannot be corrected by uptake on dust. We find that the fraction of aerosol nitrate on dust in the model increases from ~30% in fresh Asian outflow to 80–90% over the Northeast Pacific, reflecting in part the volatilization of ammonium nitrate and the resulting transfer of nitrate to the dust. Consumption of dust alkalinity by uptake of acid gases in the model is slow relative to the lifetime of dust against deposition, so that dust does not acidify (at least not in the bulk). This limits the potential for dust iron released by acidification to become bio-available upon dust deposition. Observations in INTEX-B show no detectable ozone depletion in Asian dust plumes, consistent with the model. Uptake of HNO3 by dust, suppressing its recycling to NOx, reduces Asian pollution influence on US surface ozone in the model by 10–15% or up to 1 ppb.

Emissions of Particulate Trace Elements, Metals and Organic Species from Gasoline, Diesel, and Biodiesel Passenger Vehicles and Their Relation to Oxidative Potential

Abstract: Three light-duty passenger vehicles were tested in five configurations in a chassis dynamometer study to determine the chemical and oxidative potential of the particulate exhaust emissions. The first vehicle was a diesel Honda with a three-stage oxidation system. Its main catalyst was replaced with a diesel particulate filter (DPF) and tested as a second configuration. The second vehicle was a gasoline-fuelled Toyota Corolla with a three-way catalytic converter. The last vehicle was an older Volkswagen Golf, tested using petro-diesel in its original configuration, and biodiesel with an oxidation catalyst as an alternative configuration. Particulate matter (PM) was collected on filters and subsequently analyzed using various chemical and toxicological assays. The production of reactive oxygen species (ROS), quantified by the dithiothreitol (DTT) and macrophage-ROS assays, was used to measure the PM-induced oxidative potential. The results showed that the Golf vehicle in both configurations had the highest ...

Associations of Primary and Secondary Organic Aerosols With Airway and Systemic Inflammation in an Elderly Panel Cohort

Abstract: Background Exposure-response information about particulate air-pollution constituents is needed to protect sensitive populations. Particulate matter <2.5 mm (PM2.5) components may induce oxidative stress through reactive-oxygen-species generation, including primary organics from combustion sources and secondary organics from photochemically oxidized volatile organic compounds. We evaluated differences in airway versus systemic inflammatory responses to primary versus secondary organic particle components, particle size fractions, and the potential of particles to induce cellular production of reactive oxygen species.

Ambient Particulate Matter as a Risk Factor for Suicide

Abstract: Objective:The authors assessed the relationship between exposure to ambient particulate matter and suicide in urban settings during a 1-year period. Method:The association between particulate matter and suicide was determined using a time-stratified case-crossover approach in which subjects served as their own controls. All suicide cases (4,341) in 2004 that occurred in seven cities in the Republic of Korea were included. Hourly mean concentrations of particulate matter ≤10 μm in aerodynamic diameter (at 106 sites in the seven cities) and particulate matter ≤2.5 μm in aerodynamic diameter (at 13 sites in one city) were measured. The percent increase in suicide risk associated with an interquartile range increase in particulate matter was determined by conditional logistic regression analysis after adjusting for national holidays and meteorological factors. Subgroup analysis was performed after stratification by underlying disease (cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary di...

Atmospheric Particulate Pollutants and their Relationship with Meteorology in Ahmedabad

Abstract: Urban air pollution is rapidly becoming an environmental problem of public concern worldwide It can influence public health and local/regional weather and climate In the present study, airborne particulate pollutants data were collected for a period of 4 years (2005–2008) at 13 locations in Ahmedabad, a mega city in Gujarat State in western India The particulate pollutants data were collected by the Gujarat Pollution Control Board with respirable dust samplers (RDSs) The observed Suspended Particulate Matter (SPM) concentrations varied from 660 to 7860 µg/m3, and concentrations of Particulate Matter of aerodynamic diameters less than 10 microns (PM10) ranged between 170 to 3270 µg/m3 The seasonal- and annual-average concentrations of the two pollutants were mostly above Indian air quality standards and were generally comparable with those observed in most other Indian urban areas During this study period, there was a continuous decrease of particulate pollutants concentrations within Ahmedabad; however, the concentrations were just above the permissible limits set by the Central Pollution Control Board (CPCB) These particulate pollutants concentrations were compared with meteorological variables such as rainfall, humidity, temperature, and wind speed Both SPM and PM10 showed significant negative correlations with rainfall An Air Quality Index (AQI) was calculated for all stations for all months AQI values varied from 25 to 1933 AQI was high in summer season and low in monsoon season AQI values varied from Good (0–50) to Hazardous (300–500) On the basis of the AQI scale, it is found that the atmospheric environment of Ahmedabad is moderately polluted to unhealthy range

Cytotoxic and proinflammatory effects of ambient and source-related particulate matter (PM) in relation to the production of reactive oxygen species (ROS) and cytokine adsorption by particles

Abstract: The composition of airborne particulate matter (PM) varies widely depending on its source, and recent studies have suggested that particle-associated adverse health effects are related to particle

Moisture effects on carbon and nitrogen emission from burning of wildland biomass

Abstract: . Carbon (C) and nitrogen (N) released from biomass burning have multiple effects on the Earth's biogeochemical cycle, climate change, and ecosystem. These effects depend on the relative abundances of C and N species emitted, which vary with fuel type and combustion conditions. This study systematically investigates the emission characteristics of biomass burning under different fuel moisture contents, through controlled burning experiments with biomass and soil samples collected from a typical alpine forest in North America. Fuel moisture in general lowers combustion efficiency, shortens flaming phase, and introduces prolonged smoldering before ignition. It increases emission factors of incompletely oxidized C and N species, such as carbon monoxide (CO) and ammonia (NH3). Substantial particulate carbon and nitrogen (up to 4 times C in CO and 75% of N in NH3) were also generated from high-moisture fuels, maily associated with the pre-flame smoldering. This smoldering process emits particles that are larger and contain lower elemental carbon fractions than soot agglomerates commonly observed in flaming smoke. Hydrogen (H)/C ratio and optical properties of particulate matter from the high-moisture fuels show their resemblance to plant cellulous and brown carbon, respectively. These findings have implications for modeling biomass burning emissions and impacts.

Recent Changes in Particulate Air Pollution over China Observed from Space and the Ground: Effectiveness of Emission Control

Abstract: The Chinese government has moved aggressively since 2005 to reduce emissions of a number of pollutants including primary particulate matter (PM) and sulfur dioxide (SO2), efforts inadvertently aided since late 2008 by economic recession. Satellite observations of aerosol optical depth (AOD) and column nitrogen dioxide (NO2) provide independent indicators of emission trends, clearly reflecting the sharp onset of the recession in the fall of 2008 and rebound of the economy in the latter half of 2009. Comparison of AOD with ground-based observations of PM over a longer period indicate that emission-control policies have not been successful in reducing concentrations of aerosol pollutants at smaller size range over industrialized regions of China. The lack of success is attributed to the increasing importance of anthropogenic secondary aerosols formed from precursor species including nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOC), and ammonia (NH3).

Characterization of emissions from South Asian biofuels and application to source apportionment of carbonaceous aerosol in the Himalayas

Abstract: [1] This study focuses on improving source apportionment of carbonaceous aerosol in South Asia and consists of three parts: (1) development of novel molecular marker–based profiles for real-world biofuel combustion, (2) application of these profiles to a year-long data set, and (3) evaluation of profiles by an in-depth sensitivity analysis. Emissions profiles for biomass fuels were developed through source testing of a residential stove commonly used in South Asia. Wood fuels were combusted at high and low rates, which corresponded to source profiles high in organic carbon (OC) or high in elemental carbon (EC), respectively. Crop wastes common to the region, including rice straw, mustard stalk, jute stalk, soybean stalk, and animal residue burnings, were also characterized. Biofuel profiles were used in a source apportionment study of OC and EC in Godavari, Nepal. This site is located in the foothills of the Himalayas and was selected for its well-mixed and regionally impacted air masses. At Godavari, daily samples of fine particulate matter (PM2.5) were collected throughout the year of 2006, and the annual trends in particulate mass, OC, and EC followed the occurrence of a regional haze in South Asia. Maximum concentrations occurred during the dry winter season and minimum concentrations occurred during the summer monsoon season. Specific organic compounds unique to aerosol sources, molecular markers, were measured in monthly composite samples. These markers implicated motor vehicles, coal combustion, biomass burning, cow dung burning, vegetative detritus, and secondary organic aerosol as sources of carbonaceous aerosol. A molecular marker–based chemical mass balance (CMB) model provided a quantitative assessment of primary source contributions to carbonaceous aerosol. The new profiles were compared to widely used biomass burning profiles from the literature in a sensitivity analysis. This analysis indicated a high degree of stability in estimates of source contributions to OC when different biomass profiles were used. The majority of OC was unapportioned to primary sources and was estimated to be of secondary origin, while biomass combustion was the next-largest source of OC. The CMB apportionment of EC to primary sources was unstable due to the diversity of biomass burning conditions in the region. The model results suggested that biomass burning and fossil fuel were important contributors to EC, but could not reconcile their relative contributions.

Mercury dynamics in relation to dissolved organic carbon concentration and quality during high flow events in three northeastern U.S. streams.

Abstract: [1] Mercury (Hg) contamination is widespread in remote areas of the northeastern United States. Forested uplands have accumulated a large reservoir of Hg in soil from decades of elevated anthropogenic deposition that can be released episodically to stream water during high flows. The objective of this study was to evaluate spatial and temporal variations in stream water Hg species and organic matter fractions over a range of hydrologic conditions in three forested upland watersheds (United States). Mercury and organic matter concentrations increased with discharge at all three sites; however, the partitioning of Hg fractions (dissolved versus particulate) differed among sites and seasons. Associated with increased discharge, flow paths shifted from mineral soil under base flow to upper soil horizons. As flow paths shifted, greater concentrations of dissolved organic carbon (DOC) richer in aromatic substances were flushed from upper soil horizons to stream water. The hydrophobic organic matter associated with humic material from upper soils appears to have had a greater capacity to bind Hg. Because of the strong correlation between Hg and DOC, we hypothesize that there was a concurrent shift in the source of Hg with DOC from lower mineral soil to upper soil horizons. Our study suggests that stream discharge is an effective predictor of dissolved total Hg flux.

Optical variability of seawater in relation to particle concentration, composition, and size distribution in the nearshore marine environment at Imperial Beach, California

Abstract: Beach, California, over a period of 1.5 years. Measurements included the hyperspectral inherent optical properties (IOPs) of seawater (particulate beam attenuation, particulate and CDOM absorption coefficients within the spectral range 300–850 nm), particle size distribution (PSD) within the diameter range 2–60 mm, and the mass concentrations of suspended particulate matter (SPM), particulate organic carbon (POC), and chlorophyll a (Chl). The particulate assemblage spanned a wide range of concentrations and composition, from the dominance of mineral particles (POC/SPM 0.25) with considerably greater contribution of larger‐sized particles. Large variability in the particulate characteristics produced correspondingly large variability in the IOPs; up to 100‐fold variation in particulate absorption and scattering coefficients and several‐fold variation in the SPM‐specific and POC‐specific coefficients. Analysis of these data demonstrates that knowledge of general characteristics about the particulate composition and size distribution leads to improved interpretations of the observed optical variability. We illustrate a multistep empirical approach for estimating proxies of particle concentration (SPM and POC), composition (POC/SPM), and size distribution (median diameter) from the measured IOPs in a complex coastal environment. The initial step provides information about a proxy for particle composition; other particulate characteristics are subsequently derived from relationships specific to different categories of particulate composition. Citation: Woźniak, S. B., D. Stramski, M. Stramska, R. A. Reynolds, V. M. Wright, E. Y. Miksic, M. Cichocka, and A. M. Cieplak (2010), Optical variability of seawater in relation to particle concentration, composition, and size distribution in the nearshore marine environment at Imperial Beach, California, J. Geophys. Res., 115, C08027, doi:10.1029/2009JC005554.

Atmospheric and Environmental Impacts of Volcanic Particulates

Abstract: Volcanic emissions consist of a mixture of gases, aerosol, and silicate particles, which collectively span seven orders of magnitude in size. Airborne ash and sulfate aerosol in the lower atmosphere has short-lived atmospheric and climatic effects. Volcanic aerosol injected high into the stratosphere impacts atmospheric chemical cycles and the solar and terrestrial radiation budgets, and may influence climate over longer time-scales than aerosol particles in the lower atmosphere. Once at the surface, the impacts on local environments can be substantial through transport of halogens, trace metals, and metalloids, and subsequent leaching in aqueous solutions. Volcanic emissions may cause disruption to travel and aviation, and may damage surface infrastructure, potentially causing large economic losses.