Air pollution and sudden infant death syndrome.

BACKGROUND Sudden infant death syndrome (SIDS) affects approximately 1 in 1000 live births and is the most common cause of infant death after the perinatal period. OBJECTIVE To determine the influence of air pollution on the incidence of SIDS. METHODS Time-series analyses were performed to compare the daily mortality rates for SIDS and the daily air pollution concentrations in each of 12 Canadian cities during the period of 1984-1999. Serial autocorrelation was controlled for by city, and then the city-specific estimates were pooled. Increased daily rates of SIDS were associated with increases, on the previous day, in the levels of sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide but not ozone or fine particles measured every sixth day. Effects persisted despite adjustments for season alone or the combination of daily mean temperature, relative humidity, and changes in barometric pressure for NO2 and SO2 but not carbon monoxide. RESULTS Increases in both SO2 and NO2, equivalent to their interquartile ranges, were associated with a 17.72% increase in SIDS incidence. CONCLUSION Ambient SO2 and NO2 may be important risk factors for SIDS.