Figure 2.
The distribution of: (a) PM2.5 monitoring stations; and (b) meteorological stations in China in 2015.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.