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.
Distribution of average participant PM2.5 exposures (μg/m3) for the fourth versus first quartile (Q4 vs. Q1) of surrounding building density (80%+ confidence) by time of day. The intersecting black vertical line in each histogram represents the mean value.
