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. The list below outlines the major emission categories included in the tool.

Permitted facilities: Power plants, refineries, manufacturing, recyclers
Transportation:  Passenger cars, diesel trucks, buses, airports, railroads, recreational vehicles
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 forming from the breakdown or combination of other pollutants, and the transport of emissions from natural sources such as forests, volcanoes and dust storms

Modeling results

Use these MNrisks tools to compare the contribution of different sources and pollutants to the air pollution burden in your community, or compare impacts between cities and counties.

An icon showing a blue shaded area of a metro map that represents the MNrisks pollutants prioritization tool

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MNRISKS: Pollutant priorities

Use this tool to identify the pollutants contributing most to the air pollution burden in communities across Minnesota.

An icon showing an orange Minnesota map that represents the MNrisks sources prioritization tool

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MNRISKS: Source priorities

Use this tool to identify the sources (both big and small) that contribute the most to the air pollution burden where you live or work.

How we determine the risks from air pollution

Risk assessment is a way of estimating the potential for negative health effects. Comparing pollution levels to "health benchmarks” is one way to estimate risk. A benchmark is a level below which a pollutant is unlikely to cause adverse health effects in sensitive populations. When an air concentration is above the health benchmark, the risk estimate will be greater than one. When an air concentration is below the health benchmark, the risk estimate will be less than one. The higher the number, the higher the risk.

Why are cancer risks treated differently than non-cancer risks?

Public health agencies assess risk for cancer and non-cancer diseases differently. This is due to the assumption that any exposure —no matter how small— to a pollutant that causes cancer results in a health risk. For non-cancer effects, there is an assumption of a safe dose, an exposure level that won’t result in harm.

How healthy is the air in my neighborhood?

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 US Census Bureau uses these land areas for counting populations. MNrisks can give a good idea of air quality at this scale or greater (e.g. comparing counties), but is less reliable for estimating air quality at more local scales.

Uses for MNrisks

Modeling results help 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. MNrisks modeling results cannot predict actual health outcomes. The quality of the results and uncertainties in the tool will vary by location as well by pollutant. In many cases more localized assessments, including monitoring and modeling, are needed to better characterize risk at the local level.

Methods

The technical support document below describes how MNrisks was developed. It includes the data, references, and assumptions used to estimate air emissions, model media concentrations, and quantify potential human health risks.

PDF icon MNRISKS Minnesota Statewide Screening of Human Health Risks from Air Pollution (aq9-29)