Acidic sulfate aerosols: characterization and exposure.

Abstract

Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidic aerosol in excess of 20 to 40 micrograms/m3 (as H2SO4) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO4(2)- levels. Exposures of 100 to 900 micrograms/m3/hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m3 (as H2SO4) was present in the atmosphere, and exposures less than 2000 micrograms/m3/hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H2SO4 and on what factors can be used to predict acidic sulfate episodes.

Emergency Room Visits for Respiratory Illnesses among the Elderly in Montreal: Association with Low Level Ozone Exposure

“…On the other hand, the findings of present study can be generalized to other populations with air pollution profiles similar to those of Montreal. It is likely that some parts of the air pollution effects found were due to local air pollution and some due to distant transport that occurs across certain regions of the Northeastern United States and Eastern Canada that frequently experience sulfurous smog episodes during the summer (Lioy and Waldman, 1989).…”

Diffusion Sampler for Measurement of Acidic Ultrafine Particles in the Atmosphere

“…From the early twentieth century, a number of severe sulfate acid aerosol episodes clearly demonstrate the adverse health effect of acidic aerosol on human being (Lioy and Waldman 1989;Dockery et al 1992;Chen et al 1995;Wyzga and Folinsbee 1995). The number of ambient acidic ultrafine particles (AUFPs), rather than ambient mass, is an important determining factor affecting lung injury (Dockery et al 1993;Thurston et al 1994;Pope et al 1995).…”

The effect of exposure to sulphuric acid on the early asthmatic response to inhaled grass pollen allergen

“…In a more recent study from rural Essex, the peak concentration recorded over a 62 day period in 1987 was 8.7 mg?m -3 [34]. Data from rural sites in North America have shown higher values, with maximum daily means ¡15 mg?m -3 in the summer months during [1983][1984][1985][1986], and values of ¡27 mg?m -3 over shorter periods in the late 1970s [35]. Maximum hourly average urban concentrations in the UK now rarely rise w50 mg?m -3 , although earlier this century, hourly averages may at times have exceeded 1,000 mg?m -3 .…”