Particulate Matter Exposure and Preterm Birth: Estimates of U.S. Attributable Burden and Economic Costs

Table 1. Live births and preterm births in the 48 U.S. states examined.
Parameter Value
aFor sensitivity analysis, a scenario with a 5.8-μg/m3 threshold was also used, above which all PM2.5 was considered of anthropogenic origin and an environmentally attributable fraction of 100% was applied.
Total births, 48 contiguous U.S. states, 2010 (n) 3,963,694
Preterm births, 48 contiguous U.S. states, 2010 [n (%)] 475,368 (12.0)
Reference level, base case (sensitivity analysis) 8.8 μg/m3 (5.8)a
Odds ratio per 10 μg/m3 above reference level (sensitivity analysis) 1.15 (1.07, 1.16)