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.
Monthly-averaged mass concentrations (1 = Jan; 12 = Dec) of PM2.5 constituents at seven sites in southern Arizona between 2000 – 2009 (note though that for Queen Valley/Phoenix, Saguaro West and Organ Pipe, data are only available since 2001, 2002 and 2003, respectively). “L” and “R” denote the left and right y-axis, respectively.
