Showing papers on "Particulates published in 2000"

Combustion aerosols: factors governing their size and composition and implications to human health.

Abstract: Particulate matter (PM) emissions from stationary combustion sources burning coal, fuel oil, biomass, and waste, and PM from internal combustion (IC) engines burning gasoline and diesel, are a significant source of primary particles smaller than 2.5 μm (PM2.5) in urban areas. Combustion-generated particles are generally smaller than geologically produced dust and have unique chemical composition and morphology. The fundamental processes affecting formation of combustion PM and the emission characteristics of important applications are reviewed. Particles containing transition metals, ultrafine particles, and soot are emphasized because these types of particles have been studied extensively, and their emissions are controlled by the fuel composition and the oxidant-tem-perature-mixing history from the flame to the stack. There is a need for better integration of the combustion, air pollution control, atmospheric chemistry, and inhalation health research communities. Epidemiology has demonstrated t...

Source Apportionment of Wintertime Gas-Phase and Particle-Phase Air Pollutants Using Organic Compounds as Tracers

Abstract: Two chemical mass balance receptor models are developed which can determine the source contributions to atmospheric pollutant concentrations using organic compounds as tracers. The first model uses particle-phase organic compounds to apportion the primary source contributions to atmospheric fine particulate organic carbon concentrations and fine particle mass concentrations. The second receptor model simultaneously uses both volatile gas-phase hydrocarbons and particle-phase organic compounds as tracers to determine source contributions to non-methane organic gases in the atmosphere. Both models are applied to data collected in California's San Joaquin Valley during two severe wintertime air pollution episodes. Source contributions to fine particle air quality are calculated for two urban sites, Fresno and Bakersfield, and one background site, Kern Wildlife Refuge. Primary particle emissions from hardwood combustion, softwood combustion, diesel engines, meat cooking, and gasoline-powered motor vehicles contribute on average 79% of the airborne fine particle organic compound mass at the urban sites during both episodes with smaller but still measurable contributions from fine particle road dust and natural gas combustion aerosol. Anthropogenic primary particle sources contribute less than 10% of the fine particle mass concentration at the background site. The combined gas-phase and particle-phase organic compound receptor model shows that gasoline-powered motor vehicle exhaust and gasoline vapors are the largest contributors to non-methane organic gases concentrations followed by natural gas leakage. Smaller but statistically significant contributions to organic vapors from wood combustion, meat cooking, and diesel exhaust also are quantified.

Size and composition distribution of fine particulate matter emitted from motor vehicles

Abstract: A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from motor vehicles. Measurements are made using an optical particle counter (OPC), a differential mobility analyzer (DMA)/condensation nucleus counter (CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include catalyst-equipped gasoline-powered light-duty vehicles, noncatalyst gasoline-powered light-duty vehicles, and medium-duty diesel trucks. Chemical composition analysis demonstrates that particles emitted from the gasoline-powered vehicles tested are largely composed of organic compounds while particles emitted from diesel engines contain roughly equal amounts of organic compounds and elemental carbon. The particle mass distributions from all mobile sources tested have a single mode that peaks at approximately 0.1−0.2 μm particle diameter. Of the two diesel vehicles tested, the vehicle with the lowest fine particle emissions rate released the largest number of ultrafine particles, a finding similar to that of Bagley et al. (Characterization of fuel and aftertreatment device effects on diesel emissions; Technical Report 76; Health Effects Institute: Cambridge, MA, 1996). Particle size distribution measurements taken throughout the FTP urban driving cycle used to test all of the vehicles described in this paper reveal that particulate mass emission rates and particulate size distributions from the vehicles tested here are similar during the cold start and hot start segments of the driving cycle.

Adsorption onto Aerosol Soot Carbon Dominates Gas-Particle Partitioning of Polycyclic Aromatic Hydrocarbons

Abstract: Gas-particle partitioning has an important influence on the fate of atmospheric polycyclic aromatic hydrocarbons (PAHs) and other semivolatile organic compounds (SOCs). In the present paper, gas- and aerosol-phase PAH concentrations and organic and elemental carbon concentrations in the aerosols measured in the Baltimore atmosphere and over the adjacent Chesapeake Bay in July 1997 were used to assess the mechanisms driving gas-particle partitioning of PAHs. The relative importance of adsorption onto the soot carbon and absorption into aerosol organic matter is evaluated by means of estimated soot/air (KSA) and octanol/air (KOA) partition coefficients, respectively. The results show that absorption into organic carbon may account for less than 10% of the total PAHs in the particulate phase. Adsorption onto the soot phase predicts accurately the total suspended particulate matter normalized partition coefficients (KP) for PAHs. For example, KSA predicts KP values for phenanthrene over the Chesapeake Bay wit...

Association between particulate- and gas-phase components of urban air pollution and daily mortality in eight Canadian cities.

Abstract: Although some consensus has emerged among the scientific and regulatory communities that the urban ambient atmospheric mix of combustion related pollutants is a determinant of population health, the relative toxicity of the chemical and physical components of this complex mixture remains unclear. Daily mortality rates and concurrent data on size-fractionated particulate mass and gaseous pollutants were obtained in eight of Canada's largest cities from 1986 to 1996 inclusive in order to examine the relative toxicity of the components of the mixture of ambient air pollutants to which Canadians are exposed. Positive and statistically significant associations were observed between daily variations in both gas- and particulate-phase pollution and daily fluctuations in mortality rates. The association between air pollution and mortality could not be explained by temporal variation in either mortality rates or weather factors. Fine particulate mass (less than 2.5 microns in average aerometric diameter) was a stronger predictor of mortality than coarse mass (between 2.5 and 10 microns). Size-fractionated particulate mass explained 28% of the total health effect of the mixture, with the remaining effects accounted for by the gases. Forty-seven elemental concentrations were obtained for the fine and coarse fraction using nondestructive x-ray fluorescence techniques. Sulfate concentrations were obtained by ion chromatography. Sulfate ion, iron, nickel, and zinc from the fine fraction were most strongly associated with mortality. The total effect of these four components was greater than that for fine mass alone, suggesting that the characteristics of the complex chemical mixture in the fine fraction may be a better predictor of mortality than mass alone. However, the variation in the effects of the constituents of the fine fraction between cities was greater than the variation in the mass effect, implying that there are additional toxic components of fine particulate matter not examined in this study whose concentrations and effects vary between locations. One of these components, carbon, represents half the mass of fine particulate matter. We recommend that measurements of elemental and organic carbon be undertaken in Canadian urban environments to examine their potential effects on human health.

Effective tree species for local air quality management

Abstract: Particulate pollution is a term that covers a broad spectrum of specific pollutant types, including smoke and aerosols, which permeate the atmosphere. The effects of such pollutants on human health have prompted a great deal of research effort in recent years, with the establishment of PM10 (particulate matter having an aerodynamic diameter of <10 μm) as the definition for the health-damaging fraction of the total suspended mass of particles in the atmosphere (DoE 1995). There have been a number of important medical studies that have linked high concentrations of PM10 with adverse human health effects (the first being by Dockery et al. 1993), and more recently concern has moved to the finer PM2.5 (<2.5 μm) and ultrafine particle fractions (<1 μm). The sources of these particles are many and varied in the urban atmosphere, including both naturally and anthropogenically produced matter. However, the most significant source in many urban areas comes from the exhaust fumes of road traffic (Watkins 1991). There have been a number of important medical studies linking high concentrations of PM 10 with adverse human health effects, the first being Dockery et al. (1993). More recently, concern has moved to the finer PM 2.5 (<2.5 μm) and ultrafine particle fractions (<1 μm) (Donaldson et al. 1998) As discussed by Beckett et al. (1998), trees provide many beneficial characteristics that enable them to capture pollutant particles and hence reduce their concentration in the air. The aim of this paper, therefore, is to provide the first step in a comprehensive study of the most effective use that can be made of trees for improving local air quality. The initial focus is to examine the differences in particulate capturing ability between species of tree appropriate for urban planting schemes.

Distribution, partitioning and fluxes of dissolved and particulate organic C, N and P in the eastern North Pacific and Southern Oceans

Abstract: Concurrent distributions of dissolved and suspended particulate organic carbon (DOC and POC 4641 ), nitrogen (DON and PON 4641 ) and phosphorus (DOP and POP 4641 ), and of suspended particulate inorganic phosphorus (PIP 4641 ), are presented for the open ocean water column. Samples were collected along a three-station transect from the upper continental slope to the abyssal plain in the eastern North Paci"c and from a single station in the Southern Ocean. The elemental composition of surface sedimentary organic matter (SOM) was also measured at each location, and sinking particulate organic matter (POM 4*/, ) was measured with moored sediment traps over a 110-d period at the abyssal site in the eastern North Paci"c only. In addition to elemental compositions, C : N, C : P and N : P ratios were also calculated. Surface and deep ocean concentrations of dissolved organic matter (DOM) and inorganic nutrients between the two sites displayed distinct di!erences, although suspended POM (POM 4641 ) concentrations were similar. Concentrations of DOM and POM 4641 displayed unique C, N and P distributions, with POM 4641 concentrations generally about 1}2 orders of magnitude less than the corresponding DOM concentrations. These di!erences were likely in#uenced by di!erent biogeochemical factors: whereas the dissolved constituents may have been in#uenced more by the physical regime of the study site, suspended particulate matter may have been controlled to a greater extent by biological and chemical alteration. Up to 80% of total particulate P in POM 4641 , POM 4*/, and SOM consisted of PIP. For all organic matter pools measured, elemental ratios reveal that organic P is preferentially remineralized over organic C and organic N at both sites. Increases in C : P and N : P ratios with depth were also observed for DOM at both sites, suggesting that DOP is also preferentially degraded over C and N as a function of depth. A simple one-dimensional vertical eddy di!usion model was

Comparison of Emissions and Residential Exposure from Traditional and Improved Cookstoves in Kenya

Abstract: Suspended particulate matter and carbon emissions from the combustion of biomass, in addition to their environmental consequences, have been causally associated with the incidence of respiratory and eye infections. Improved stoves offer the potential for emissions reduction. We compare the emissions of suspended particulate matter and carbon monoxide from traditional and improved biofuel stoves in Kenya under the actual conditions of household use. Data for analysis is from 137 14-h days of continuous real-time emission concentration monitoring in a total of 38 households. Our analysis shows that improved (ceramic) wood-burning stoves reduce daily average suspended particulate matter concentration by 48% (1822 μg/m3; 95% C.I. 663−2982) during the active burning period and by 77% (1034 μg/m3; 95% C.I. 466−1346) during the smouldering phase. Ceramic stoves also reduce the median and the 75th and 95th percentiles of daily emission concentration during the burning period and the 95th percentile during the smo...

Human‐activity‐enhanced formation of organic aerosols by biogenic hydrocarbon oxidation

Abstract: Tropospheric aerosol can affect climate and the chemistry of the atmosphere. Organic particulates form a significant fraction of the atmospheric suspended matter over forested areas and may originate to a large extent from the oxidation of natural hydrocarbons. A three-dimensional global model of the troposphere is used to evaluate the contribution to the global organic aerosol (OA) source of the secondary organic aerosol (SOA) derived from the ozonolysis of biogenic volatile organic compounds (BVOC) and its evolution since preindustrial times. BVOC have been represented by a mixture of α- and β-pinenes, and their aerosol-forming parameters and chemical reactivities versus O3, OH, and NO3 have been estimated using laboratory information. An important factor in SOA formation is the deposition of condensable aerosol oxidation products onto preexisting organic aerosol, and this has been taken into account. The thus-calculated source of SOA is evaluated to have increased from 17–28 Tg/yr in preindustrial times to 61–79 Tg/yr at present. This threefold to fourfold enhancement of the formation of organic aerosol from natural BVOC is attributed to an increase in ozone and organic aerosol from anthropogenic sources. The main uncertainties involved in our calculations are related to the composition of BVOC emissions and the details of their aerosol formation capabilities.

Determination of Pd, Pt and Rh in airborne particulate and road dust by high-resolution ICP-MS: a preliminary investigation of the emission from automotive catalysts in the urban area of Rome

Abstract: At present there is increasing concern as regards the release of Pd, Pt and Rh, i.e., the Pt-group elements (PGEs), from catalytic converters for automotive exhaust control. A study was undertaken to investigate the concentrations of PGEs in airborne particulate matter and road dust in different sites of Rome and to compare the obtained data with airborne samples collected in 1991 (i.e., before the wide-scale adoption of car catalysts). The analytical technique employed was inductively coupled mass spectrometry (ICP-MS) combined with ultrasonic nebulization (UN). Airborne particulate matter and road dust were collected in different periods of the year both from several urban (high traffic) zones and one suburban (low traffic) site. The experimental results obtained so far point to a significant difference between the group of urban sites and the remote site. PGEs in the urban area for airborne particulate matter spanned the ranges (in pg m−3) 21.2–85.7, 7.8–38.8 and 2.2–5.8 for Pd, Pt and Rh, respectively. In road dust, the ranges (in ng g−1) were 102–504 for Pd, 14.4–62.2 for Pt and 1.9–11.1 for Rh. Moreover, a spot comparison of the data pertaining to the current sampling with those of a set of samples collected in 1991 confirms that the contribution of catalytic converters to the environmental presence of the said elements can no longer be neglected. Therefore, in consideration of the adverse effects of PGEs and the large number of cars equipped with catalytic converters, continued monitoring of the three elements in environmental media and biota should be undertaken in urban sites.

Associations between mortality and air pollution in central Europe.

Abstract: Increased mortality has been observed in association with elevated concentrations of air pollutants in European cities and in the United States. We reassessed the effects of particulate matter in C...

Air quality in Malaysia: impacts, management issues and future challenges.

Abstract: Objective Observations have been made on the long-term trends of major air pollutants in Malaysia including nitrogen dioxide, carbon monoxide, the ozone and total suspended particulate matter (particularly PM10), and sulfur dioxide, emitted from industrial and urban areas from early 1970s until late 1998. Methodology The data show that the status of atmospheric environment in Malaysia, in particular in highly industrialized areas such as Klang Valley, was determined both by local and transboundary emissions and could be described as haze and non-haze periods. Results During the non-haze periods, vehicular emissions accounted for more than 70% of the total emissions in the urban areas and have demonstrated two peaks in the diurnal variations of the aforementioned air pollutants, except ozone. The morning 'rush-hour' peak was mainly due to vehicle emissions, while the late evening peak was mainly attributed to meteorological conditions, particularly atmospheric stability and wind speed. Total suspended particulate matter was the main pollutant with its concentrations at few sites often exceeding the Recommended Malaysia Air Quality Guidelines. The levels of other pollutants were generally within the guidelines. Since 1980, six major haze episodes were officially reported in Malaysia: April 1983, August 1990, June 1991, October 1991, August to October 1994, and July to October 1997. The 1997 haze episode was the worst ever experienced by the country. Short-term observations using continuous monitoring systems during the haze episodes during these periods clearly showed that suspended particulate matter (PM10) was the main cause of haze and was transboundary in nature. Large forest fires in parts of Sumatra and Kalimantan during the haze period, clearly evident in satellite images, were identified as the probable key sources of the widespread heavy haze that extended across Southeast Asia from Indonesia to Singapore, Malaysia and Brunei. The results of several studies have also provided strong evidence that biomass burning is the dominating source of particulate matter. The severity and extent of 1997's haze pollution was unprecedented, affecting some 300 million people across the region. The amount of economic costs suffered by Southeast Asian countries during this environmental disaster was enormous and is yet to be fully determined. Among the important sectors severely affected were air and land transport, shipping, construction, tourism and agro-based industries. The economic cost of the haze-related damage to Malaysia presented in this study include short-term health costs, production losses, tourism-related losses and the cost of avertive action. Although the cost reported here is likely to be underestimated, they are nevertheless significant (roughly RM1 billion). Conclusions The general air quality of Malaysia since 1970 has deteriorated. Studies have shown that should no effective countermeasures be introduced, the emissions of sulfur dioxide, nitrogen oxides, particulate matter, hydrocarbons and carbon monoxide in the year 2005 would increase by 1.4, 2.12, 1.47 and 2.27 times, respectively, from the 1992 levels.

Evolution of atmospheric particles along trajectories crossing the Los Angeles basin

Abstract: Trajectory analysis shows that the air masses arriving at Riverside, CA, on the afternoons of September 24 and 25, 1996, previously passed near air monitoring sites at Santa Catalina Island, Long Beach, and Fullerton, CA, in succession. At those sites, electrical aerosol analyzers and optical particle counters acquired continuous particle size distribution data, inertial impactor and bulk filter samples were taken with 4-h time resolution for determination of particle size and chemical composition during intensive sampling periods once per day at each site, and aerosol time-of-flight mass spectrometers acquired continuous data on particle size and composition at the single-particle level. These data permit particle evolution to be studied within single air masses as they sequentially pass several monitoring sites over a 2-day period. Air parcels associated with both of the trajectories studied show mineral dust, organic carbon, particulate nitrate and ammonium, and total suspended particulate matter concentrations that increase as transport occurs across the air basin. Large increases in particulate ammonium and nitrate concentrations occur between Fullerton and Riverside due to overnight air stagnation in an area with high gaseous ammonia emissions. The aerosol time-of-flight mass spectrometers show how the externally mixed population of individual particles is modified chemically during transport from Long Beach to Riverside, CA. The coastal aerosol at Long Beach containing sea-salt particles and primary carbon particles is changed substantially as these particles individually accumulate secondary ammonium nitrate and organics during travel across the air basin.