Environmental Public Health Tracking: Air Quality Data

Wisconsin Tracking provides information about air quality in Wisconsin.

Air pollution means something is in the air that should not be there or should be there in smaller amounts.

We host data on air quality measures that have standard levels defined by the federal government. These measures include particulate matter under 2.5 microns (PM2.5) and ozone.

Wisconsin Tracking gets information about these air pollution measures from air monitoring stations all over Wisconsin.

Access the air quality data

For more information about types of air pollution, visit the air quality issues page.

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Join the environmental health listserv by sending an email to DHS Environmental Public Health Tracking with the subject line "Join envhealth listserv."

Frequently asked questions

What are air pollutants?

Air pollutants are substances in the air that should not be there or should be there in smaller amounts. These unwanted substances might be gases, liquids, or solids.

Where does air pollution come from?

Many air pollutants result from human activities such as smoking, driving, manufacturing, and burning wood or coal. Pollution can also come from natural events such as wildfires.

How am I exposed to air pollution?

You can be exposed to pollutants from the air by breathing in contaminated air or contaminated dust particles.

What are the health effects of air pollution?

Air pollution is linked to lung and heart problems. It is also linked to asthma and can make health problems, such as emphysema, worse. The United States Environmental Protection Agency (EPA) provides a full list of the health effects of particulate matter and ozone.

How do I know if I am at risk?

The first step is to know if you live in an area of the state that has high levels of pollution. Accessing the Wisconsin Tracking air pollution data will tell you how your community is doing over time. Additional information can be found on the Wisconsin DNR website.<.p>

If you are concerned about your personal risk, you can contact Wisconsin Tracking or your regional Department of Natural Resources office. You can also view daily current air quality information for Wisconsin or a map of current air quality for selected counties.

What is the data source?

Wisconsin Tracking focuses on pollutants that are regulated by the United States government. The government regulates these pollutants through the Environmental Protection Agency (EPA). In Wisconsin, the Department of Natural Resources (DNR) provides standards for air quality. The data on our portal are from DNR monitoring stations around Wisconsin.

Which measures do you use for air pollution?

Data for two types of air pollution are available on the data portal:

  • Particulate matter under 2.5 microns (PM2.5)
  • Ozone

Can individuals use Wisconsin Tracking data to see if they have been exposed to air pollution?

The science that links air pollution to health and disease is complex. We do not suggest that you use Wisconsin Tracking data to look for specific links between your health and your environment. This is because a number of factors – such as time and other exposures – can be important. The data on our public data portal only provide a general level of pollution for different regions of Wisconsin over longer periods of time. As such, these data cannot be used to assess your personal risk. These data can tell you if the level of air pollution in your area of the state is changing over time.

Where can I learn more about air pollution?

Air quality data details

Data Details

Read frequently asked questions about the air quality data

Ozone

Annual days above standard

This measure is the annual number of days with maximum eight-hour average ozone concentration above the National Ambient Air Quality Standard. The measure includes both monitored and modeled data. The monitored data comes from the U.S. Environmental Protection Agency (EPA) Air Quality System (AQS). When AQS data are available from multiple monitors for a given county and day, the highest eight-hour maximum (daily) ozone concentration among all the monitors is selected for purposes of creating daily county-level data. EPA provides modeled estimates of ozone using Downscaler (DS) model, which uses a statistical approach to fuse monitored data in areas where monitors exist, and relies on Community Multi-scale Air Quality (CMAQ) modeled output in areas without monitors. DS modeled estimates are available by census tract centroid; the geographic center of the census tract. Daily county-level modeled estimates are obtained by selecting the maximum value observed among all the census tracts within each county. County-level ozone measures are created using monitor data when available and using modeled estimates for days and locations without such data.

Annual person-days above standard

This measure is the annual number of person-days with maximum eight-hour average ozone concentration above the National Ambient Air Quality Standard. The measure includes both monitored and modeled data. The monitored data comes from the U.S. Environmental Protection Agency (EPA) Air Quality System (AQS). When AQS data are available from multiple monitors for a given county and day, the highest eight-hour maximum (daily) ozone concentration among all the monitors is selected for purposes of creating daily county-level data. EPA provides modeled estimates of ozone using Downscaler (DS) model, which uses a statistical approach to fuse monitored data in areas where monitors exist, and relies on Community Multi-scale Air Quality (CMAQ) modeled output in areas without monitors. DS modeled estimates are available by census tract centroid; the geographic center of the census tract. Daily county-level modeled estimates are obtained by selecting the maximum value observed among all the census tracts within each county. County-level ozone measures are created using monitor data when available and using modeled estimates for days and locations without such data.

Particulate matter less than 2.5 micrometers (PM2.5)

Annual person-days above standard

This measure is the annual number of person-days with particulate matter less than 2.5 micrometers (PM2.5) levels above the National Ambient Air Quality Standard. The measure includes both monitored and modeled data. The monitored data comes from the U.S. Environmental Protection Agency (EPA) Air Quality System (AQS). When AQS data are available from multiple monitors for a given county and day, the highest 24-hour average (daily) PM2.5 concentration among all the monitors is selected for purposes of creating daily county-level data. EPA provides modeled estimates of PM2.5 using Downscaler (DS) model, which uses a statistical approach to fuse monitored data in areas where monitors exist, and relies on Community Multi-scale Air Quality (CMAQ) modeled output in areas without monitors. DS modeled estimates are available by census tract centroid; the geographic center of the census tract. Daily county-level modeled estimates are obtained by selecting the maximum value observed among all the census tracts within each county. County-level PM2.5 measures are created using monitor data when available and using modeled estimates for days and locations without such data.

Average annual concentration (μ/m3)

This measure is the annual average ambient concentration of particulate matter less than 2.5 micrometers (PM2.5) in micrograms per cubic meter (based on seasonal averages and daily measurements). The measure includes both monitored and modeled data. The monitored data comes from the U.S. Environmental Protection Agency's (EPA) Air Quality System (AQS). When AQS data are available from multiple monitors for a given county and day, the highest 24-hour average (daily) PM2.5 concentration among all the monitors is selected for purposes of creating daily county-level data. EPA provides modeled estimates of PM2.5 using Downscaler (DS) model, which uses a statistical approach to fuse monitored data in areas where monitors exist, and relies on Community Multi-scale Air Quality (CMAQ) modeled output in areas without monitors. DS modeled estimates are available by census tract centroid the geographic center of the census tract. Daily county-level modeled estimates are obtained by selecting the maximum value observed among all the census tracts within each county. County-level PM2.5 measures are created using monitor data when available and using modeled estimates for days and locations without such data.

Glossary and definitions of terms

Explore definitions and explanations of terminology found on the portal, like age-adjusted rate and confidence intervals.

Last Revised: August 3, 2022