Retrospective Exposure Assignment for Epidemiologic Studies

STI staff have compiled a unified ambient air quality database from routine monitoring programs and special monitoring studies that covers the last 25 years and the entire nation, plus portions of Canada and Mexico. These data are frequently used in air pollution health effects studies to assign exposures retrospectively to participants. Locations are based on residential postal-ZIP codes or hospital locations. Daily exposure metrics for ozone, NO₂, CO, SO₂, VOCs, PM_2.5 mass, PM₁₀ mass, sulfate, nitrate, ammonia, ammonium, organic carbon, elemental carbon, and trace elements are archived. The ambient data have been used in life time exposure studies, cross-sectional studies of pulmonary function, time-series studies of mortality, hospital admissions, emergency room visits, school absences, and case cross over studies of asthmatic hospital visits. STI staff offer advice on the most appropriate air quality databases, and provide cohort exposure assignments on a daily, monthly, and annual basis.