Air pollution and infant mortality in Mexico City

Historic air pollution episodes of the 1950s led to acute increases in infa nt mortality, and some recent epidemiologic studies suggest that infant or child mortality may still result from air pollution at current levels. To i nvestigate the evidence for such an association, we conducted a time-series study of infant mortality in the southwestern part of Mexico City in the y ears 1993 to 1995 using mortality data from death registrations and air pol lution measurements from a monitoring station we operated. Excess infant mo rtality was associated with the level of fine particles in the days before death, with the strongest association observed for the average concentratio n of fine particles during the period 3 to 5 days previously: a 10-mu g m(- 3) increase in the mean level of fine particles during these 3 days was ass ociated with a 6.9% excess of infant deaths (95% confidence interval 2.-11. 3%), Infant mortality was also associated with the levels of nitrogen dioxi de and ozone 3 to 5 days before death, hut not as consistently as with part icles.