Air modeling and human health

The MPCA studies the cumulative impacts of air pollution to help prioritize environmental efforts throughout Minnesota. Many sources of air pollution, both big and small, contribute to an individual’s exposure and the MPCA tries to account for all of them. To help us understand the health risks air pollution poses to Minnesotans, the MPCA developed a risk-screening tool called MNRISKS.

Health benchmarks and air pollution scores

MNRISKS compares air pollution levels against health benchmarks to estimate the potential for negative health effects. A health benchmark is an amount of pollution in the air that is unlikely to result in health effects after a lifetime of exposure. Health benchmarks are set to be protective of known sensitive populations. 

Comparing the amount of air pollution in an area against the health benchmarks will result in a ratio; MNRISKS reports this number as an air pollution score.

  • Air pollution score equals 1:  air pollution levels are at the health benchmarks
  • Air pollution score higher than 1:  air pollution levels are above the health benchmarks
  • Air pollution score less than 1:  air pollution levels are below the health benchmarks.

How is the air in my neighborhood?

Our environmental justice map tool displays MNRISKS information.

Click on the “MPCA air pollution score” tab and zoom in to see the air pollution score for an area, how it compares to the rest of Minnesota, and the pollutants and sources contributing most to the air pollution score in that area.

Areas colored in purple on the map have air pollution scores >1 and are above health benchmarks. Higher numbers mean higher risk.

Pollution sources

Pollution sources included in the tool:

  • Permitted facilities: Power plants, refineries, manufacturers, foundries, printers, recyclers
  • Transportation (traffic): Passenger cars, SUVs, pick-up trucks, vans, recreation vehicles, boats, diesel trucks, buses, airports, railroads
  • Residential: Home heating, backyard fires, lawn mowers, cleaning products, open burning
  • Commercial and industrial: Large boilers, diesel equipment, dry cleaners, gas stations, construction equipment
  • Wildfires and prescribed burns: Forest fires, agricultural burning, grassland and park fires
  • Non-local sources – background and secondary formation: Pollution formed from the breakdown or combination of other pollutants, and the transport of emissions from natural sources such as forests, volcanoes, and dust storms

Census block groups

MNRISKS provides information about air quality averaged for census block groups in Minnesota. A block group is an area of land where about 600 to 3,000 people live. The U.S. Census Bureau uses census block groups to count the population.

MNRISKS can give a good idea of air quality at the census block group scale and larger areas such as census tracts (about 40–50 block groups) or counties. Localized assessments, including monitoring and modeling, are often needed to better characterize risk at a smaller local scale. MNRISKS cannot predict individual health outcomes.

Uses for MNRISKS

An air pollution score at or above 1 does not necessarily mean that health effects are occurring in a particular area, but it does demand investigation into the sources and prioritization of efforts to reduce the pollutants contributing most to benchmarks being exceeded.

MNRISKS helps regulators prioritize emission reduction activities, air monitoring locations, and other efforts to improve air quality. These may include focusing on specific pollutants or geographic areas, double-checking estimates of air emissions provided by permittees, and identifying disproportionate impacts to specific populations.

Methods

MNRISKS is refreshed every three years when air toxics emissions inventory data is released. Between refreshes, adjustments are made as updated data becomes available.

The first version of MNRISKS was released in 1999. Refer to the posted technical support document for background on how MNRISKS was developed. It includes the data, references, and assumptions used to estimate air emissions, model concentrations, and quantify potential human health risks.