||National Oceanic and Atmospheric Administration, Research Triangle Park, NC. Atmospheric Sciences Modeling Div. ;Harvard School of Public Health, Boston, MA.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
Ambient air samples of strong acid aerosol, sulfate, ammonia, and ammonium were collected in Pittsburgh and Uniontown, Pennsylvania during the summer of 1990. High correlations were found for both acid aerosol and sulfate concentrations between Pittsburgh and the semi-rural site in Uniontown. One possible implication is that acid aerosols and their precursors are regionally transported. To test this hypothesis, air samples from the Uniontown site were statistically analyzed for the meteorological relationships that resulted in episodic events of elevated ambient acid aerosol levels. Standard measures of atmospheric conditions in both Pittsburgh and Uniontown were used; they included temperature, pressure, relative humidity, wind speed and direction. Results show that the episodic events of elevated acid aerosol occurred with the same general set of meteorological conditions. The major meteorological variables which correlated with the episodes were the mean wind speed in Pittsburgh and the mean westerly wind component (U) at Uniontown. These two variables accounted for one-third of the variance.