Welcome to the Wisconsin Department of Natural Resources Air Quality Monitoring Data site.

General Information

The statewide monitoring network is spatially distributed to provide air quality information based on geographic coverage and population density. As required by the Clean Air Act, the U.S. EPA sets National Ambient Air Quality Standards (NAAQS) for criteria pollutants:

• Carbon monoxide
• Ground level zone
• Lead
• Nitrogen oxides
• Particulate matter
• Sulfur dioxide

The DNR conducts ambient air monitoring in locations directed by federal requirements to measure concentrations of these criteria pollutants for comparison to the appropriate NAAQS. For more extensive information visit DNR's monitoring webpage.

Data Validity

• Data presented on this website is displayed in real time. It has not been quality assured and is therefore subject to change.
• Data is quality assured within six months of collection.
• Reports may not follow all rounding/truncation conventions required for comparison to the regulatory National Ambient Air Quality Standards. For example, 8-hour average ozone concentrations on this website have been rounded rather than truncated, so the values listed may be one ppb higher than their regulatory values.

Time

• Data posted is the most recent available, but may appear to be older due to several factors:
  • Data polls after the top of the hour and the website is updated after polling is complete.
  • Data is timestamped using the beginning hour; for example, the 1-hour average for 7:00-7:59 is given the "07" hour time stamp.
  • Central Standard Time is always used, so data will appear to be an additional hour behind during Daylight Savings Time.

Air Quality Index (AQI)

• Read more on the AQI page.

Parameter Specifications

• Barometric Pressure – station conditions corrected to sea level
• PM_2.5 – micrograms per cubic meter in local conditions
• PM₁₀ – micrograms per cubic meter corrected to standard conditions (25 °C, 1 atmosphere pressure)
• PM Coarse (particulate matter between 10 and 2.5 mm in size) – micrograms per cubic meter in local conditions
  • Not expected to match the difference between PM₁₀ and PM_2.5 in many cases because the PM₁₀ concentrations have been corrected to standard conditions