Detroit's Air Pollution: Causes And Concerns

Detroit has a serious air pollution problem. In 2024, the Detroit metro area was ranked 13th worst in the nation for annual particle pollution, with Wayne County, Michigan, receiving a failing grade for pollution levels above the federal standard. The city's air pollution is caused by a combination of industrial and transportation activity, with coal-fired power plants, coke, steel and cement facilities, petroleum refineries, and vehicles all contributing to high levels of air pollution. This has resulted in serious health consequences for Detroit residents, including premature deaths, hospitalizations for respiratory and cardiovascular disease, and increased asthma attacks in children.

Industrial pollution sources

Detroit is known for its many large industrial pollution sources, which are called point sources. These include coal-fired power plants, which are among the city's heaviest emitters of sulfur dioxide (SO2). Annually, these two plants alone release a combined 34,000 tons of sulfur dioxide into Detroit's air. SO2 is a dangerous gas that converts to sulfates in the atmosphere, contributing to fine particle pollution that causes harm to the lungs. Other point sources include coke, steel, and cement facilities, petroleum refineries, and incinerators.

The heavy concentration of factories and vehicles in the southwest section of Detroit has been cited as a major factor in reducing overall air quality. Each of these individually contributes high levels of air pollution, and their combined emissions can lead to unhealthy concentrations of particulate matter in the air. Mobile sources, such as cars, trucks, trains, and other vehicles, emit a substantial amount of PM2.5, NOx, and other pollutants. Mobile sources cause an estimated 150 hospitalizations, up to 18,000 respiratory symptom days among children with asthma, 1,200 lost workdays, and 11 deaths.

In addition to the type and quantity of pollutants emitted, exposure is influenced by the proximity of emission sources to homes, schools, playgrounds, and other frequented locations. Detroit has many large neighbourhoods and schools adjacent to large industrial facilities. About 69,000 Detroit residents live within 150 meters of a major freeway, and 58 Detroit public schools (operating in 2014-15) with an estimated 24,490 students are within 200 meters of a major roadway.

The Detroit metro area was ranked 13th worst in the nation for annual particle pollution in the American Lung Association's 2024 "State of the Air" report. Wayne County, Michigan, received a failing grade for pollution levels above the federal standard. The Detroit-Warren-Ann Arbor, MI metro area ranked 33rd worst in the nation for ozone pollution, with an average of 5.7 unhealthy days per year in Macomb County, Michigan.

Mobile sources

The impact of mobile sources on air quality in Detroit is evident in the high levels of particle pollution in the city. Detroit has been ranked among the worst cities in the nation for annual particle pollution, and mobile sources play a crucial role in this issue. The emissions from vehicles contribute to the high concentrations of particulate matter in the air, which can have severe health consequences for residents.

One of the primary pollutants emitted by mobile sources is nitrogen oxides (NOx), which includes nitrogen dioxide (NO2). NO2 is a harmful gas pollutant that can irritate the lungs and lead to respiratory issues. When exposed to heat and sunlight, NO2 reacts with volatile organic compounds (VOCs) to form ground-level ozone, another dangerous pollutant. Ozone is a key component of smog and is highly reactive, causing irritation and significant adverse health effects.

The proximity of major roadways and freeways to residential and educational institutions in Detroit further exacerbates the impact of mobile sources on air quality. Approximately 69,000 Detroit residents live within 150 meters of a major freeway, and numerous Detroit public schools are located within 200 meters of busy roadways. This close proximity increases the exposure of residents and students to the pollutants emitted by mobile sources, heightening the health risks associated with air pollution.

The health burden attributed to mobile sources in Detroit is substantial. It is estimated that mobile sources cause approximately 150 hospitalizations, up to 18,000 respiratory symptom days among children with asthma, 1,200 lost workdays, and 11 premature deaths annually. The combined impact of mobile and point sources (such as industrial facilities) results in a significant number of disability-adjusted life years (DALYs) and a high monetized value of the health burden, amounting to $660 million each year.

Climate change

Detroit is known for its large industrial pollution sources, such as coal-fired power plants, coke, steel, and cement facilities, petroleum refineries, and incinerators. These sources emit harmful pollutants like sulfur dioxide (SO2) and nitrous oxides (NOx), which can irritate the lungs and lead to respiratory issues and other health problems. For example, a pair of coal-fired power plants in Detroit release a combined 34,000 tons of SO2 into the air annually. Southwest Detroit, in particular, has four of Michigan's highest emitters of SO2 and NOx, contributing to high levels of air pollution.

Mobile sources, including cars, trucks, and other vehicles, also emit substantial amounts of pollutants such as PM2.5, NOx, and other harmful gases. Detroit's heavy industrial and transportation activity impact nitrogen dioxide (NO2) and volatile organic compound (VOC) levels in the air. When NO2 and VOCs react with heat and sunlight, they create ozone, a highly irritating gas pollutant. As levels of harmful gas pollution increase, so does ground-level ozone, especially during weekdays when industrial and transportation activities are most active.

The effects of air pollution in Detroit are significant, with an estimated 721 premature deaths, 1,500 hospitalizations for respiratory and cardiovascular diseases, and over 200,000 days with respiratory symptoms among children with asthma attributed to outdoor air pollution. Climate change exacerbates these issues, and stronger national limits on ozone pollution are needed to protect public health and drive the cleanup of polluting sources.

Wood burning

Wood smoke particles are very small, ranging from 0.2 microns at the start of the burn period to 0.05 microns as the burn cycle progresses. These ultrafine particles are the most dangerous to inhale as they can lodge in the lungs and travel through the bloodstream, causing cardiovascular problems, including heart attacks, strokes, and congestive heart failure. They can also cause premature births in pregnant women.

According to a report by Utah Physicians for a Healthy Environment, wood smoke is a significant contributor to overall community air pollution worldwide. Dr. Wayne Ott of Stanford University states that "the largest single source of outdoor fine particles (PM 2.5) entering into our homes in many American cities is our neighbor's fireplace or wood stove." He adds that "only a few hours of wood burning in a single home at night can raise fine-particle concentrations in dozens of surrounding homes throughout the neighborhood."

The EPA estimates that particulate pollution from wood smoke is 12 times more carcinogenic than an equal amount of second-hand cigarette smoke. Wood smoke also contains toxic and/or cancer-causing substances, such as benzene, formaldehyde, and benzo-a-pyrene, a polycyclic aromatic hydrocarbon (PAH). PAHs are considered one of the most toxic compounds in air pollution.

To reduce wood smoke pollution, it is recommended to limit the amount of wood burned and ensure that stoves or fireplaces are operated correctly and do not leak. Modern, EPA-certified wood stoves are designed to reduce the amount of particulate matter released, but even these emit some pollution. Alternative heating methods, such as gas furnaces, electric fireplaces, or electric split ductless heat pumps, are better options for reducing air pollution.

Coal-fired power plants

Detroit Edison (DTE) is a prime example of a company that has skirted the law by erroneously labelling the rebuilding of its ageing coal plants as "routine maintenance". DTE's coal plants in Michigan have emitted hundreds to thousands of tons of additional harmful air pollutants every year. For instance, the River Rouge coal-fired power plant in Southwest Detroit, Michigan, has been surrounded by low-income communities of colour. In 2010, a study was commissioned to quantify the deaths and other health effects attributable to fine particle pollution from coal-fired power plants. The River Rouge Power Plant was required to shut down one of its two coal-fired boilers by the end of 2016, with the full plant retired in 2021.

Sulfur dioxide (SO2), a harmful air pollutant made up of sulfur and oxygen, is a by-product of burning fuel that contains sulfur, such as coal. Annually, two coal-fired power plants in Detroit release a combined 34,000 tons of sulfur dioxide into the city's air. SO2, a dangerous gas, converts to sulfates in the atmosphere when gas particles collide and coagulate, contributing to fine particle pollution that causes harm to the lungs.

While the US has made progress in reducing emissions from coal-fired power plants, these plants remain a major source of pollution. The Clean Air Act of 1970 allowed many existing coal plants to continue operating without installing modern pollution controls. However, some individual plants have yet to install environmental equipment to control emissions, and the transition to electric automobiles may make it difficult to eliminate coal as a power source.

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