Colorado is in the midst of an effort to reduce ozone air pollution. High levels of ozone present health concerns both for healthy adults and for sensitive people, particularly the elderly, young children and those with asthma or other respiratory ailments. Symptoms include stinging eyes and throats, chest pains, coughing and breathing difficulty.
Metropolitan Denver and the north Front Range were classified as a "marginal" nonattainment area by the EPA effective July 20, 2012. A nonattainment area is one in which air quality does not meet the ozone standards set forth by the federal government in 2008, which is 75 parts per billion over an eight-hour period.
The marginal nonattainment designation does not impose any new planning requirements on Colorado at this time; however, the nonattainment area must meet the standard before 2015 or new requirements may be imposed.
Colorado Ozone Action Plan (Including the 2008 Revisions to the State Implementation Plan)
Ozone Transport in the West An exploratory study that documents long-range transport of ozone and precursor emissions that affect ozone levels in the Western United States.