Staff Publications Subject(s): Natural Resources & Environment Public Health Published: November 3, 2023 Agency: Legislative Council Staff This memorandum focuses on ground-level ozone, the harmful air pollutant that is the main ingredient of “smog.” Ground-level ozone significantly impacts the health of Coloradans and the environment. It is also important to note that ground-level ozone differs from “good” ozone, or stratospheric ozone, which occurs naturally in the upper atmosphere and forms a protective layer that shields the earth from the sun's harmful ultraviolet rays. Download Document