Particulate air pollution and daily mortality in Steubenville, Ohio

Particulate air pollution has been associated with daily mortality in London, England, both in the smog episodes of the 1950s and at the lower pollution levels of the late 1960s and early 1970s. Replicating these findings in the United States has been difficult, because particulates are usually sampled every sixth day. Replication, particularly with a gravimetric measure of particulates, is important in assessing the causality of the relation. Daily measurements of total suspended particulates by high volume gravimetric sampler are available for the Steubenville, Ohio, metropolitan area. These were matched to daily mortality counts from the detail mortality tapes of the National Center for Health Statistics. Deaths of residents which occurred outside the Steubenville Standard Metropolitan Statistical Area were excluded. Because of the much smaller population, the average total number of deaths per day in the Steubenville Standard Metropolitan Statistical Area over the 11-year period 1974-1984 was about 1% of the deaths in a typical London winter. Despite this reduced statistical power, total suspended particulate count was significantly associated with increased daily mortality in Poisson regression analyses controlling for season and temperature. An increase in particulates of 100 micrograms/m3 was associated with a 4% increase in mortality on the succeeding day. Associations with sulfur dioxide were not significant after adjustment for particulates. The relation appeared to continue at levels well below the current National Ambient Air Quality Standard.