Fig. 1From: First trimester exposure to ambient gaseous air pollutants and risk of orofacial clefts: a case–control study in Changsha, ChinaLocation of monitoring stations included in the study. There are 15 air pollution monitoring stations and 4 meteorological monitoring stations. The 15 air pollution monitoring stations consist of 10 from Changsha, 3 from Xiangtan, and 2 from Zhuzhou, respectivelyBack to article page