Figure 2. Fine Particulate Matter (PM 2.5) Levels Dropped at the Start of the Stay-at-Home Order, Returned to Normal in April and May

Percent change of PM 2.5 monthly average concentrations in 2020, compared to 2010-2019 averages

Note: Highlighted bars designate stay-at-home months.
Chart: Colorado Health Institute Source: Source: CDPHE, 2010-2020