David Rich, Sc.D.; Junfeng Zhang, Ph.D.
University of Rochester, University of Southern California
NIEHS Grants R01ES019165, R01ES015864
NIEHS grantees report that women who were in their eighth month of pregnancy during the 2008 Beijing Olympics, when the Chinese government implemented policies to reduce air pollution levels, gave birth to children with higher birth weights compared to women pregnant before and after the games.
The air pollution controls implemented during the Beijing Olympics lasted for 6 to 7 weeks and were then relaxed, creating a natural experiment in which to study air pollution effects. The pollution controls produced a 60 percent reduction in sulfur dioxide, 48 percent reduction in carbon monoxide, 43 percent reduction in nitrogen dioxide, and a reduction in particulate matter less than 2.5 microns in diameter (PM2.5).
The researchers examined birth records from 83,672 full-term babies born to mothers in four urban Beijing districts. They found that babies with their eighth month of pregnancy occurring during the Beijing Olympics were on average 23 grams larger than those with their eighth month of pregnancy falling in the same dates in 2007 and 2009. The researchers observed that interquartile range increases in PM2.5 (19.8 micrograms per cubic meter), carbon monoxide (0.3 parts per million), sulfur dioxide (1.8 parts per billion), and nitrogen dioxide (13.6 ppb) concentrations during the eighth month of pregnancy were associated with 18g (-32g, -3g), 17g (95% CI: -28g, -6g), 23g (95% CI: -36g, -10g), and 34g (95% CI: -70g, 3g) decreases in birth weight, respectively. No significant associations were seen for pregnancy months one through seven.
Citation: Rich DQ, Liu K, Zhang J, Thurston SW, Stevens TP, Pan Y, Kane C, Weinberger B, Ohman-Strickland P, Woodruff TJ, Duan X, Assibey-Mensah V, Zhang J. 2015. Differences in birth weight associated with the 2008 Beijing Olympic air pollution reduction: results from a natural experiment. Environ Health Perspect; doi:10.1289/ehp.1408795 [Online 28 April 2015].