Measuring the Health Impacts of Air Pollutants - Minnesota Dept. of Health

Measuring Health Impacts of Fine Particles in Air

The following web page provides information about the Minnesota Department of Health (MDH) project, “Measuring the Impact of Particulate Matter Reductions by Environmental Health Outcome Indicators.”

Information on this page:

What are fine particles?

Among the many components of air are small particles composed of a diverse mixture of solids and liquid droplets that vary in size, shape, chemical composition, and origin. Very small particles are able to pass through the throat and nose and enter the lungs where they may cause health problems. Particles that are 2.5 micrometers in diameter or smaller are called “fine particles” or PM2.5. They are released when coal, gasoline, diesel fuels, wood, and other fuels are burned. They may also be formed by reactions in the atmosphere involving gases released from fuel burning and other sources.

How do fine particles impact health?

Both short and long-term exposures to fine particles have been associated with harmful effects on respiratory and cardiovascular health.

Short-term exposures to fine particles can range from a few hours to several days, and have been linked to acute health outcomes such as asthma attacks, heart attacks, and sudden deaths.

Long-term exposures to fine particles take place over several years, and have been associated with health outcomes that develop or worsen over time, such as lung cancer and deaths from cardiopulmonary disease.

What is being done to reduce fine particle air pollution in MN?

In the last few years, several local and regional air pollution reduction strategies have been implemented in Minnesota. Several of these changes have taken place in the Minneapolis-St. Paul (MSP) metropolitan area, where there are major pollutant sources (traffic, coal-burning power plants).

Some examples of these air pollution reduction strategies include:

  • Minnesota Metro Emissions Reduction Project (MERP): a $1 billion voluntary initiative by Xcel Energy to reduce air emissions from three Twin Cities area power plants
  • Project Green Fleet and Clean Air Minnesota: these programs focus on reducing emissions from school buses and other diesel vehicles through retrofit technology.

At the same time, nationwide initiatives and policies have also been targeting air pollution:

Shown below is a timeline of these local and national air pollution reduction strategies:

Timeline of fine particle activities

What is MDH doing to evaluate the health impacts of these changes?

The Minnesota Department of Health (MDH), with funding from the US Environmental Protection Agency, is developing methods to track the health impacts of these changes in air quality in Minnesota.

MDH is working with partners at the Minnesota Pollution Control Agency (MPCA) and Olmsted Medical Center (Rochester, MN) to examine:

  • Have there been measurable changes in outdoor air quality, especially fine particles, during the time that these air pollution reduction strategies were taking place?
  • Can we measure the acute respiratory and cardiovascular health effects associated with changes in air quality? Can we track these health impacts over time?

Why are we doing this project?

Reductions in the emission of air pollutants are expected as a result of the local air pollution reduction strategies and national initiatives. This project provides a unique opportunity for MDH to use available air quality and health data to help determine if people have been exposed to fewer fine particles overall, and if that has led to better health outcomes.

Flowchart of why this project is important.

This project will also allow MDH to develop and test analytical methods to conduct similar types of analyses in the future.

How are we doing this project?

MDH is focusing on two study locations for this project: the MSP metropolitan area and Olmsted County.

We are using a 7-county area (Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, and Washington Counties) to define the MSP metropolitan area. This area is an important study location because this is where several major pollutant sources in Minnesota are located. It is also where the majority of the local air pollution reduction strategies are taking place.

Olmsted County, home to Mayo Clinic and Olmsted Medical Center, has fewer major pollutant sources than the MSP metropolitan area. The city of Rochester, the third largest city in Minnesota outside of Minneapolis and St. Paul, is located in Olmsted County.

Map of study locations

MSP 7-county metro

Olmsted County

MDH is using two statistical methods to study the association between concentrations of fine particles measured in the air and health outcomes. Both of these methods allow MDH to assess how hospitalizations and deaths may be associated with short-term exposures to fine particles.

The following are the health outcomes being examined in this project:

Hospitalizations for:

  • All respiratory conditions
  • Chronic lower respiratory disease
    • Including asthma, chronic obstructive pulmonary disease (COPD), emphysema, chronic bronchitis, pulmonary fibrosis
  • Asthma
  • Cardiovascular disease

Emergency department visits for:

  • Asthma

Deaths due to:

  • Cardiopulmonary conditions
  • All causes

The analyses use data from years 2003 to 2009 (however, only 2005-2009 was available for emergency department visits).

What is the project timeline?

MDH will complete this project in late Spring 2012. Results will be posted on this web page and shared through other communications and outreach activities.

Project presentations

  • Measuring respiratory impacts of particulate matter reductions by environmental public health indicators, Minneapolis-St. Paul, 2003-2009. Presented at the Promoting Healthy Communities EPA Conference, Washington DC, September 2011. [PDF:1 page/335KB]
  • Minnesota Air Quality: Challenges and Implications for Public Health. Presented at MN Environmental Public Health Tracking Seminar Series, St. Paul, MN, January 2011.
  • Fine particle air pollution and cardiovascular health outcomes in Minnesota, 2003-2009. Presented at the Annual Conference of the Council of State and Territorial Epidemiologists, Pittsburgh, PA, June 2011.
  • Using case-crossover analysis to measure health impacts of air pollution reduction strategies in Minnesota. Presented at the Annual Conference of the Council of State and Territorial Epidemiologists, Portland, OR, June 2010.
  • Measuring the impacts of air pollution reduction strategies on respiratory hospitalizations in Minnesota. Presented at the American Association for Aerosol Research Specialty Conference on Air Pollution and Health, San Diego, CA, March 2010.
  • Johnson J. Tracking progress and measuring the impacts of particulate matter reduction strategies in Minnesota. Presented at the Annual Conference of the International Society for Exposure Science, Minneapolis, MN, November 2009.

How can I find more information?

For questions or additional information about this project, please contact Jean Johnson by email at or phone (651) 201-5902.

For information about fine particles and air quality, see:

This project is supported under an EPA STAR research grant (grant number R833627). This is part of an initiative to develop environmental public health indicators to build linkages between environmental hazards, human exposures, and public health outcomes.

Principal investigators:
Jean Johnson, MDH
Gregory C. Pratt, MPCA
Barbara Yawn, Olmsted Medical Center

Project team:
Lisa Herschberger, MPCA
Paula Lindgren, MDH
Margaret McCourtney, MPCA
Kari Palmer, MPCA
Naomi Shinoda, MDH
Allan Williams, MDH
Peter Wollan, Olmsted Medical Center