Identifying air pollution sources in Southwest Detroit

An illustration of a city with different types of buildings and smog in the background.

New research from Michigan Public Health

Air pollution is known to cause a host of negative effects on human health, with urban populations at particular risk. The National Institute of Environmental Health Sciences (NIEHS) estimates that 9 out of 10 urban area residents are impacted by air pollution.

In order to address the disproportionate impact of air pollution on urban populations, there's a need to identify major sources of emissions. Recently, a University of Michigan School of Public Health research team released a new study in the journal Atmosphere that aims to identify these sources in an area of Michigan with some of the highest levels of air pollution in the country: Southwest Detroit.

In particular, Michigan Public Health researchers sought to identify the major sources of particulate matter (PM2.5) in Southwest Detroit, using data collected over six years (2016-2021) to contrast with previous data collected from 2001-2014.

"These microscopic particles pass deep into the lung, and exposure causes not only respiratory disease like asthma, but also heart attacks and premature death. Children, older adults, people with heart or lung conditions, and minority populations are especially at risk," said Stuart Batterman, professor of Environmental Health Sciences at Michigan Public Health and senior author of the study. "Such serious health effects can be prevented if we can identify and limit the emissions that cause PM2.5 exposure."

Study Findings

The researchers highlight several points of significance from their findings, including:

  • Mobile sources of emissions (i.e., exhaust from vehicles and construction equipment) make up the largest source of PM2.5 levels, at 40 percent.
  • Industrial sources of emissions from coal and fossil fuels are in a decline, but still sizable. Researchers note that the closure of coal-burning power plants and other facilities contributed to this decline.
  • Emissions from manufacturing, processing, and metals production facilities saw only modest changes over the past decade.
  • During the 2016-2021 study period, the levels of PM2.5 in Detroit ranged from 8 to 11 micrograms per cubic meter. The EPA standard limit during this time was 12 micrograms per cubic meter. Currently, EPA is revising this standard and considering limits between 8 and 10 micrograms per cubic meter. With revised standards, portions of Michigan—including Detroit—would exceed the federal limit, which will trigger many measures by the EPA, state and local authorities to reduce PM2.5 emissions with the goal of achieving the standard within 5 years.

The study also found no significant changes in PM2.5 levels during the COVID-19 pandemic, with the exception of what the researchers called “short-lived decreases” early in 2020.

"Like many other areas, the lockdown early during the pandemic reduced traffic-related pollutants, but traffic and industrial sources later resumed near normal levels, while other sources like many power plants and much of the truck traffic never stopped," Batterman said. 

Community-academic partnerships in Southwest Detroit

Southwest Detroit has the highest levels of air pollution in Michigan and ranks among the top five percent in the country. Community organizations, health providers, and public health researchers alike are working together to address the area’s pollution challenges and enact change to improve health and wellbeing of the community. Michigan Public Health researchers are fostering these collaborations with community stakeholders to promote health equity through methods of community-academic partnerships.

One example is Community Action to Promote Healthy Environments (CAPHE). Housed within Michigan Public Health, CAPHE’s goal is to develop and implement components of a scientifically-based, community-led public health action plan to reduce air pollution and associated adverse health effects in Detroit and surrounding communities.

Addressing particulate matter in the air

Identifying major sources of air pollution is one of the first steps in increasing air quality and ultimately improving the health of the community. Based on their findings, researchers are optimistic that there are numerous evidence-based solutions that can be implemented to address PM2.5 pollution. 

Batterman noted some trends:

The gradual electrification of the vehicle fleet and elimination of Michigan’s many dirty fossil fuel power plants with wind and solar energy will reduce emissions and help improve air quality. It may be difficult, however, to meet the new PM2.5 standards, especially near certain industries, large roads and construction sites. And this summer we’ve seen a new challenge—the wildland fire smoke coming from Canada. These fires are episodic, and often the smoke goes elsewhere, but as we saw in past weeks, these fires can produce unprecedented levels of pollution. We can’t predict when fires and smoke will next occur, but climate change makes such air pollution episodes more likely.

The researchers also note that there’s still work to be done, particularly as new industry, warehouses, and the Gordie Howe International Bridge are constructed and bring additional exposure to particulate matter in the air.

The investigators plan to update their study in the next several years to confirm trends and identify PM2.5 sources. Reducing emissions will be essential to attaining the new air quality standards and improving health in Southwest Detroit.

Additional authors include Zhiyi Yang, Md Kamrul Islam, and Tian Xia, from Michigan Public Health.

Paper cited: “Apportionment of PM2.5 Sources across Sites and Time Periods: An Application and Update for Detroit, Michigan,” Atmosphere.


Destiny CookDestiny Cook

Senior Public Relations Specialist
University of Michigan School of Public Health