Visitors to Rocky Mountain National Park marvel at the deep blue skies, cotton clouds, and fresh air (though some visitors might declare it too thin). Park managers aim to maintain high standards of air quality. Research and monitoring are showing the park's air quality is affected by air pollution coming from a variety of human made sources. Air pollution in the park reduces visibility, increases ozone levels, and causes excess nitrogen deposition.
High ozone levels can have an immediate health effect on park visitors. Individuals with preexisting respiratory conditions such as asthma or emphysema may be affected when exerting themselves, especially in the park's high elevation environment. Ozone advisories are announced when levels are expected to reach unhealthy levels and are posted at the visitor centers and entrance stations.
Since ozone is produced by the interaction of nitrous oxides, sunlight, and heat, the park is prone to high ozone levels on warm, summer afternoons and evenings. Car exhaust from Front Range communities is a main source of nitrous oxides.
Also, there are 11 different plant species in the park that are known to be susceptible to injury from high ozone levels. A five-year study from 2006 to 2010 documented ongoing leaf injury from ozone in the park.
Nitrogen is transported by wind, combined with moisture in the air, and then deposited in the park by rain or snow. Although nitrogen is an important part of the park's ecosystems, deposition of excess atmospheric nitrogen at fifteen times the natural rate is impacting natural resources.
The National Park Service, State of Colorado, and Environmental Protection Agency are working together to implement a Nitrogen Deposition Reduction Plan to reduce nitrogen deposition to tolerable rates by 2032. Colorado crop and livestock producers are exploring ways to further reduce agriculture's contribution through nitrogen best management practices. To download a fact sheet, click here.