Beijing’s air pollution has been blamed for lung cancer and other diseases, scaring away tourists, and making life difficult for foreign companies—and now, in an especially stark piece of research, it has been linked to lower birth weights for babies born in China’s smoggy capital.
A study published in Environmental Health Perspectives found that babies born in Beijing in 2007 and 2009 were on average 23g (0.05lbs) lighter than those born soon after the 2008 Beijing Olympics, when authorities took extreme measures to clean up the city’s air. The findings confirm suspicions that exposure to air pollution in the late stages of pregnancy can result in lower birth weights, which are associated with adverse health outcomes later in life.
In the run-up to and during the Beijing Games, the Chinese government shut down factories and restricted car and truck traffic to ensure clear skies in the capital. Specifically, the findings show that mothers whose eighth month of pregnancy coincided with that clear period gave birth to heavier babies. Mothers whose second month of pregnancy occurred during the Olympics’ blue sky days saw no significant benefit.
The thorough job the Beijing government did of clearing its air for the Olympics provided an opportune moment to conduct a natural experiment on babies’ birth weights, but the implications of the study can be applied to cities worldwide. After all, despite the massive negative attention that Beijing’s air receives, it is hardly the worst in the world.