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Results of recent research show that particulate matter (PM) composition and size vary widely with both space and time. Despite the variability in PM characteristics, which are believed to influence human health risks, the observed relative health risk estimates per unit PM mass falls within a narrow range of values. Furthermore, no single chemical species appears to dominate health effects; rather the effects appear to be due to a combination of species. Non-PM factors such as socioeconomic status and lifestyle are also believed to affect the health risk, although accounting for these confounding factors is challenging. Airborne PM is also responsible for a number of effects aside from human health, such as alterations in visibility and climate. Because the PM problem is associated with a range of societal issues such as energy production and economic development, making progress on reducing the effects of PM will require integrated strategies that bring together scientists and decision makers from different disciplines to consider tradeoffs holistically. [ABSTRACT FROM AUTHOR]

The article introduces the January 2, 2004 issue of the journal Aerosol Science and Technology. In July 1997, the U.S. Environmental Protection Agency (EPA) issued new National Ambient Air Quality Standards for fine particulate matter (PM). EPA recognized that an improved understanding of the key sources, development of the most cost effective control strategies, and health risks associated with PM would depend on the availability of high quality measurements of PM composition, and concentration over a variety of spatial and temporal scales. This special issue of reports on results from various air quality measurement projects and spans the full range of objectives for these projects.

Conventional PM[sub 10] inlets available operate at a flow rate of 16.7 l/min. The purpose of this study was to develop and test a PM[sub 10] inlet designed to operate at 50 l/min to be used with a recently developed continuous coarse particle monitor (Misra et al.). Laboratory tests using polystyrene latex particles established the inlet's 50% cutpoint at 9.5 µm. Further evaluation of PM[sub 10] inlet was performed in a wind tunnel at wind speeds of 3, 8, and 24 km/h. Tests showed that the 50% efficiency cutpoint as well as the very sharp particle separation characteristics of the inlet were maintained at these wind speeds. Field evaluation of the PM[sub 10] inlet was performed in Riverside and Rubidoux, CA. A 2.5 µm cutpoint round nozzle virtual impactor was attached downstream of the developed PM[sub 10] inlet. The Dichotomous PM[sub 10] Partisol Sampler, operating at a flow rate of 16.7 l/min was used as a reference sampler. The Dichotomous Partisol uses an FRM PM[sub 10] inlet operating at 16.7 l/min to remove particles larger than 10 µm in aerodynamic diameter. Commercially available 4.7 cm Teflon filters were used in both the Partisol and the PM[sub 10] inlet to collect particulate matter (PM). Results showed good agreement between coarse PM (2.510 µm) mass concentrations measured by means of the PM[sub 10] inlet and Partisol. Chemical analyses showed excellent agreement between coarse PM concentrations of Al, K, Si, Ca, and Fe obtained by the two samplers. The agreement also persisted for nitrate and sulfate. Finally, the excellent agreement between coarse concentra- tions of the PM[sub 10] inlet and Partisol persisted for wind speeds up to 19 km/h. [ABSTRACT FROM AUTHOR]

The chemical composition of PM[sub 2.5] was investigated at four sites (Rubidoux, CA, Phoenix, AZ, Philadelphia, PA, and Research Triangle Park, NC) in January and February of 1999. Three samplers were used to determine both the overall mass and the chemical composition of the aerosol. Teflon filters were weighed for total mass. Ions were analyzed using ion chromatography. Elements were determined using X-ray fluorescence. Organic and elemental carbon were measured using a thermo-optical method. At all of the sites, reconstructed mass was observed to be greater than or equal to the measured mass. Good ionic balance was found for ammonium, nitrate, and sulfate at each of the sites. Overall, the chemical composition of the aerosol for each site was in good agreement with the expected composition based upon previous studies, with the exception of relatively high nitrate contribution to the total mass at Philadelphia. Good agreement was found between the predicted amount of sulfate by XRF analysis of sulfur and the sulfate measured by ion chromatography. As expected, sulfate was a more important contributor to the total mass at the East Coast sites. Nitrate contributed more to the total mass at the West Coast sites and was an important factor in the highest observed mass concentration at Rubidoux. Teflon filters appear to lose nitrate to a greater extent than heat-treated quartz fiber filters. Organic carbon was also found to be the largest part of the aerosol mass on minimum days for all sites and a significant portion of the mass on other days with 25-50% of the total mass at all of the sites. At three of the sites, organic carbon (OC) collected on denuded filters was less than that found on nondenuded samples, indicating an absorptive artifact on the quartz fiber filters. It was also found that the crustal component to PM[sub 2.5] was highest at Phoenix. PM[sub 2.5] was also found to contribute significantly to the PM[sub 10] particle mass at all the sites. [ABSTRACT FROM AUTHOR]

A preface for the October 2006 issue of the periodical "Aerosol Science and Technology" is presented.

Highlights the American Association for Aerosol Research conference entitled "Particulate Matter: Atmospheric Sciences, Exposure, and the Fourth Colloquium on PM and Human Health" in April 2003. Goal of the conference; Discussion on aerosol measurement methods and characteristics of urban aerosols; Associations cosponsoring the event.