Early life exposure to particulate matter and childhood asthma in Beijing, China: a case-control study.

A case-control study was conducted to examine the association of particulate matter exposure during the pre-natal (the first, second, and third trimesters. and the whole pregnancy) and post-natal periods (the first year after birth) with childhood asthma in Beijing, China. Multivariable logistic regressions showed that childhood asthma was significantly associated with exposures to PM _2.5 and PM ₁₀ during the entire pregnancy, with ORs of 1.28(95%CI:1.06-1.56) and 1.21(95%CI:1.02-1.42), respectively. The highest association with a 10 μg/m ³ increase in PM _2.5 and PM ₁₀ were both seen for the second trimester, with ORs of 1.17(95% CI: 1.05-1.30) and 1.14(95% CI: 1.04-1.24). Subgroup analyses suggested that significant and positive effects were subject to be observed in children with a family history of atopy. This study added evidence that exposures to PM _2.5 and PM ₁₀ during pregnancy might increase the risk of childhood asthma in seriously polluted area, highlighting stronger associations in the second trimester.