Figure 1.
Map of geological coal deposits and study villages in Xuanwei and Fuyuan counties. Classification of coal regions based on the State Standard of China Coal Classification (GB5751-86); 1/3 coking, coking, gas fat, and meager lean coals are subtypes of smoky coal. *Historic smokeless coal deposit.
Figure adapted from Fig. 1 in “Lung cancer risk by geologic coal deposits: A case–control study of female never-smokers from Xuanwei and Fuyuan, China” by Wong et al.17. Adapted with permission.