Estimating fine particulates less than 2.5 microns in aerodynamic diameter (PM2.5) from airport visibility data in California.

Methods were developed for estimating fine particulates less than 2.5 microns in aerodynamic diameter (PM2.5) from airport visibility data which detected seasonality and allowed for possible site- and season-specific regressions of PM2.5 on visibility. The methods were applied to nine airports in California in order to produce estimates of PM2.5 for the years 1966-1986 based on 1,767 paired PM2.5/visibility data points where PM2.5 had been measured at a monitoring station near the airport. General F-tests indicated that site- and season-specific regression equations resulted in a statistically significant reduction in residual error. The split halves correlation for estimating PM2.5 from visibility over all areas was 0.82. The methods were used to estimate long-term concentrations of ambient PM2.5 for an epidemiological cohort of 1,868 individuals.