Infant mortality and air pollution:: Modifying effect by social class

Studies link air pollution with increased mortality; however, information on infants is scarce and inconclusive. Objective: We studied short-term PM10 exposure, relating to increased respiratory-related infant mortality, and estimated for poor living conditions. Methods: A case-crossover approach modeled the relationship between infant mortality (1 month-1 year of age), and ambient PM10 levels on days before death in Ciudad Juarez, Mexico (1997-2001). Socioeconomic level (SES) of the deceased was defined by residence location. Results: Overall air pollutants did not affect infant mortality (odds ratio [OR] = 1.02, 95% confidence interval [CI] = 0.94-1.11 for PM10, lag-1) but low SES increased risk. Each 20 mug/m(3) in PM10 (24-hour average, lag1, cumulative over 2 previous days) increased respiratory-related mortality (OR = 1.61, 95% CI = 0.97-2.66; OR = 2.56; 95% CI = 1.06-6.17, respectively). Ozone levels did not affect infant mortality for any SES. Conclusions: Worse living conditions among lower SES concurred with increased mortality.