The Impact of Migration on Air Quality Dose-Response Functions: A Case Study of Jacksonville,Florida

The purpose of this study was to analyze quantitative relationships between air pollution and mortality, and to examine the impact of migration on pollution-related mortality functions. Dose-response functions were estimated for intra-urban variations in ambient air quality for the city of Jacksonville, Florida. Indices of air pollution used in this study were sulfur dioxide (SO₂) and total suspended particulates (TSP). Ambient air quality was measured by the dispersion of TSP and SO₂ across census tracts using the SYMAP dispersion model in conjunction with air quality monitoring stations.

Holding other things constant, TSP apeared to have no statistically significant association with mortality rates. By contrast, the significance of the estimated coefficient for the pollution variable, SO₂, supported the contention that there is a positive and statistically significant relationship between air pollution and mortality rates. However, after making a limited test of the impact of migration on dose-response functions, the SO₂ pollution variable was no longer statistically significant. That is, recent migrants may have limited exposure to the existing level of SO₂ in Jacksonville, Florida, but carry with them long term exposure to more heavily polluted areas in the Northern United States. The results of this study suggest that further epidemiological studies and economic analysis of the health effects on air pollution should make some attempt to control the migration effect.