Fig. 1
Geographic and population distribution of 28 provinces/cities in the CHARLS in 2018. Each province/city on the map is gradually darkened in color as the number of participants increases
Fig. 1 | BMC Pulmonary Medicine
Geographic and population distribution of 28 provinces/cities in the CHARLS in 2018. Each province/city on the map is gradually darkened in color as the number of participants increases