 This study examined the correlation between common air pollutants and common birth defects in Xiamen, China. The results showed that exposure to sulfur dioxide, SO2, during the first and second months of pregnancy increased the risk of certain birth defects, including congenital heart disease, cleft lip and or cleft palate, and ear deformities. This suggests that SO2 may be a contributing factor in the development of these birth defects. This article was authored by Xi Minghuang, Yuqiao, Zhou Enqi, and others.