There's a lot to learn about healthy air. It's important to understand the following terms in order to make sense of the data about Dane County's air quality. Find additional information on our Employer Toolkits page.


The Air Quality Index (AQI)
This measure is used to report actual levels of ozone and fine particle pollution. The higher the levels, the greater the health concern. You can check Wisconsin's daily air quality.

Ground-level Ozone
Ozone, a gas that is the main ingredient of smog, is a concern during the summer months. Even at low levels, it can affect respiratory health. It is formed when two primary pollutants—oxides of nitrogen (NOx) and volatile organic compounds (VOCs) are “cooked” by sunlight and high temperatures. Emissions from cars and trucks are responsible for more than half of ozone air pollution in Dane County.

Fine Particle Pollution
Microscopic airborne particles (1/30th the size of a human hair) can occur year-round but levels are typically higher in the winter. The smaller the particle, the greater the health risk to children, older adults and people with asthma and heart ailments. Major contributors to fine particle pollution include trucks, passenger cars, off-road equipment, electric power generation, wood burning and agricultural sources.

Clean Air Action Days
When the Air Quality Index is forecast to be at an unhealthy level for sensitive groups of people, the Dane County Clean Air Coalition alerts the public. The Coalition asks government agencies, businesses and citizens to cut down voluntarily on activities that produce air pollution. Taking action reduces the chances of our community exceeding the federal health standards. You can sign up for personal e-mail notification and learn what steps you can take on Clean Air Action Days.

The United States Environmental Protection Agency holds the responsibility for determining whether or not a region of the country has attained or has not attained federal standards of health for air quality. The US EPA assigns the Wisconsin Department of Natural Resources the responsibility to manage air quality laws and regulations at the state level and state legislation enables Wisconsin to implement federal law. While the DNR monitors air quality scientifically, and reports monitoring data to the federal EPA, the EPA designates regions within the state that are in attainment or non-attainment status based on that data. Non-attainment status triggers federal regulations to bring the region back into attainment of air quality standards.


Factsheets and Papers
Fine Particle Pollution (PM2.5) Issue Paper
Designation of Nonattainment Areas for the Fine-Particles (PM2.5) Standard
Sources of Fine Particle Pollution in Dane County