Ground Level Ozone

Ozone is most likely to reach unhealthy levels on hot sunny days in urban environments but can still reach high levels during colder months. Ozone can also be transported long distances by wind, so even rural areas can experience high ozone levels.  

Exposure to high concentrations of ozone can include the following health effects: 

  • Eye irritation. 
  • Difficulty in breathing / shortness of breath.
  • Aggravated / prolonged coughing and chest pain. 
  • Increased aggravation of asthma. 

Ozone also impacts vegetation by reducing agricultural crop and forest yield, causing leaf injury, diminishing resistance to pests and disease and reducing tree seedling survival. 

To see the current Air Quality Index values for different pollutants including ozone at the state monitoring sites, visit the CDPHE Colorado Air Quality site. For hourly ozone concentration data, visit the CDPHE Ozone real-time data table. 

Nonattainment Area Information

map of ozone nonattainment area for Colorado

Ground level ozone is regulated by the Environmental Protection Agency (EPA). Under the EPA’s authority, the State of Colorado’s Air Quality Control Commission (AQCC) and the Air Pollution Control Division (APCD) are tasked with developing and enforcing regulations and implementing modeling and monitoring plans to reduce ozone concentrations and achieve the EPA’s designated National Ambient Air Quality Standards (NAAQS). The NAAQS are set to protect the public against adverse health effects.  

Nonattainment Areas (NAA) are areas that have been designated as not meeting/attaining the ozone standard or contributing to areas not meeting the ozone standard. Currently Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer, and Weld counties are part of the Denver Metro/North Front Range (DM/NFR) ozone non-attainment area. The DM/NFR NAA is currently classified as Serious nonattainment of the 2015 standard and as Severe nonattainment for the 2008 standard.  

 

      
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