Air pollution, primarily from cars and industrial plants, is spiking cancer cases in the Midwest, with Chicago-area residents breathing some of the most polluted air in the country. That’s the upshot of new research that found a significant link between air pollution and several types of cancer — including lung, breast, ovarian, bone, endometrial and blood cancer — in the metropolitan Chicago area.
The research, which is in line with other studies of air pollution and cancer, also found that minorities in urban neighborhoods face significantly higher risks, in part because communities of color are more likely to live in densely populated areas with higher levels of contaminants.
“People living in that community are exposed to those chemicals. There’s more industry, but there’s also more people living in a particular area, more per square foot, more cars in that area and more factories,” says Ajaz M. Khan, M.D., M.B.A., C.P.E., chief of the Department of Medical Oncology at City of Hope® Cancer Center Chicago.
“Chicago is a heavily industrialized city — there are a lot of cars, a lot of people and a lot of buildings, and all of those things play a huge role in Chicago’s cancer rate.”
Air pollution not only raises the risks for developing cancer but also poses health problems for people living with cancer or undergoing treatment. That’s why it’s important for residents of Chicago, other Midwestern states and elsewhere to take steps to limit their exposure to air pollution.
This article will explore:
- What causes unhealthy air quality?
- Chicago air quality
- Michigan air quality
- Minnesota air quality
- Wisconsin air quality
- Air quality and cancer risk
- Impact on cancer patients and survivors
- How to protect yourself
If you or a loved one is concerned about possible signs or symptoms of cancer and would like an initial appointment or a second opinion, call us 24/7 at (877) 834-8941.
What Causes Unhealthy Air Quality?
Air pollution comes from a variety of sources, including automobiles, industrial facilities, power plants and wildfires.
The U.S. Environmental Protection Agency (EPA) has identified five major outdoor air pollutants linked to cancer that are regulated by the Clean Air Act:
- Ground-level ozone smog
- Particle pollution (also known as particulate matter)
- Carbon monoxide
- Sulfur dioxide
- Nitrogen dioxide
The EPA has established an Air Quality Index (AQI) for these major air pollutants and set national air quality standards to protect public health.
The AQI includes six color-coded categories, designating a range of air quality and health concerns — from good to hazardous. The higher the AQI value, the greater the level of pollution and concern.
Sensitive groups include:
- Children, whose airways are smaller than adults and still developing
- Older individuals whose immune systems may not function as well to protect them from inhaled contaminants
- People with chronic conditions, such as cancer, asthma and other lung diseases, heart disease and diabetes
- Individuals with lower socioeconomic or low-income status who may have lower rates of health coverage and less access to quality, affordable care and may live near pollution sources.
Chicago Air Quality
Urban areas in the United States have some of the highest levels of air pollution in the nation, research shows. But on a single day last July, Chicago had the worst air quality in the world.
In addition to the typical sources of air pollution in Chicago, a haze of Canadian wildfire smoke blanketed the area on July 31, and no other city in the world had higher levels of air pollution, according to a ranking by IQ Air, a Swiss air-technology company. The National Weather Service issued an air quality alert for all of Illinois that lasted two days.
But even before the Canadian wildfires, the metro area had some of the highest levels of pollution in the country.
The American Lung Association’s 2025 “State of the Air” report concluded the air quality in the greater Chicago area has worsened in recent years, with residents exposed to unhealthy ozone smog and particle pollution year-round. The report ranked Metro Chicago 15th worst in the nation for ozone pollution — with 20.3 unhealthy days per year, receiving a failing grade from the association. The metro area also received a failing grade for year-round particle pollution, ranking 13th worst in the nation.
Nationally, the report found that nearly half of the United States population, about 156 million people, live in areas with unhealthy levels of air pollution.
City of Hope researchers have also found Chicago’s air quality is particularly hazardous in certain heavily industrialized communities and neighborhoods. Loretta Erhunmwunsee, M.D., F.A.C.S., vice president and chief health access and community enrichment officer at City of Hope Medical Center in Los Angeles, led a new report that identified several pollution “hotspots” in Chicago’s Cicero suburb and parts of its south and west sides. Residents in these areas face high cancer risks, due to industrial emissions of so-called polycyclic aromatic compounds and particulate pollution, which are linked to increased risks for leukemia and other blood cancers, as well as cancers of the bone, brain, breast, colon, endocrine system, lung, pancreatic, prostate and thyroid.
Michigan Air Quality
Illinois isn’t the only Midwestern state with high pollution-cancer risks.
Newly published research has found that, in Michigan, nonsmokers who live near industrial plants are more likely than those living further away to develop lung cancer and be diagnosed at an advanced stage.
Although smoking is the leading cause of lung cancer, studies are increasing showing the disease is increasingly diagnosed in never-smokers who may have been exposed to environmental contaminants.
To reach their conclusions, researchers at Detroit-based Henry Ford Health examined 2,223 lung cancer cases from 2013 to 2021 in Wayne County, as well as the EPA’s air quality and pollution data from 1980 to 2018.
The researchers concluded that the closer residents lived to a facility that released carcinogenic pollutants such as particulate matter, carbon monoxide, sulfur dioxide, nitrogen dioxide and volatile organic compounds, the more likely they were to develop lung cancer.
Also worth noting: On the same day last July that Chicago topped the world’s air pollution measures, Detroit ranked seventh globally.
Minnesota Air Quality
Minnesota has also experienced high pollution levels in certain areas that have raised concerns about cancer risk. The air quality in the Twin Cities metro area, for instance, has worsened over the past 10 years, according to the American Lung Association’s 2025 “State of the Air” report.
Residents are exposed to higher levels of ozone smog and particle pollution, and they experienced more unhealthy days over the past decade. Greater Minneapolis ranks as the 48th worst in the nation for ozone pollution with more than five unhealthy days per year, earning the metro area a failing grade. The area also received failing marks for particle pollution, ranking 36th worst with nearly five unhealthy days annually.
And Minneapolis ranked the third-most polluted city in the world on the same day last July that Chicago topped the global air pollution list.
Wisconsin Air Quality
Wisconsin’s air quality, over time, has been stable, with fewer spikes in pollution than those seen in Illinois and Michigan, according to AQI measures. Since 2020, the overall air quality in Wisconsin was within the “good” range for most of the year.
Even so, some regions of the state have higher levels of cancer-causing pollution, due to automobiles, power plants, oil refineries, industrial facilities and factories. In 2016, the American Lung Association ranked Sheboygan as the 22nd most ozone smog-polluted city in the country.
Air Quality and Cancer Risk
Air pollution sources not only exacerbate lung conditions like asthma and emphysema, they may also cause genetic changes that disrupt normal cell functions and cause cancer. While some genetic mutations are inherited, the vast majority of cancers are linked to environmental carcinogens and unhealthy lifestyles, studies have shown. Tiny pollution particles may build up in the lungs and damage the DNA in cells, causing inflammation and changing how cells divide, which may lead to cancer.
The National Cancer Institute estimates that environmental/lifestyle factors — including contaminants in the air we breathe, the water we drink and the foods we eat — account for at least two-thirds of all cancer cases. It’s estimated that as many as 1 in 10 lung cancer cases alone is caused by air pollution.
“The most common cancer linked to air pollutants is lung cancer,” Dr. Khan says. “Usually, it’s smoking in combination with other contaminants. But breast cancer, certain childhood malignancies, leukemia, renal cell cancer, kidney cancer and head and neck cancers can be associated with air pollutants as well.”
Impact on Cancer Patients and Survivors
Poor air quality not only increases cancer risk, it may also have adverse effects on cancer patients and survivors, particularly those with respiratory conditions or who are receiving chemotherapy and/or radiation therapy.
Exposure to pollutants may complicate treatment and interfere with the efficacy of some therapies, too, research has shown.
“The survivorship answer is still a complex one, just because of the number of patients we diagnose and treat,” Dr. Khan says. “But does poor air quality affect the quality of life of patients and survivors? The obvious answer is yes.”
That’s why it’s important for patients to be aware of air pollution levels and take special precautions to protect their health during treatment.
How to Protect Yourself
While we have control over some environmental carcinogens, like cigarette smoke and excessive sun exposure, it’s much harder to avoid pollutants in the outdoor air and in our drinking water, experts note.
Still, there are some steps people can — and should — take to protect themselves, particularly when the air quality is hazardous.
The first priority is to monitor air quality warnings issued by local, state and federal health officials and keep a close eye on the EPA’s AQI index. When the air quality is poor, people should:
- Limit time outdoors as much as possible
- Wear an N-95 mask can help filter out dangerous particulate matter
- Run a portable air purifier at home or use a high-quality filter in central air-conditioning units, if possible
Engaging in other healthy activities — such as exercising, which improves lung function and overall health — also helps mitigate risks, Dr. Khan adds.
It’s especially important for individuals living in Chicago and other areas with high air pollution to be screened for cancer and other health conditions linked to environmental contaminants.
City of Hope’s Chicago hospital and its national network of cancer treatment locations, offers top-rated screening and diagnosis programs and leading-edge therapies for all types of cancer. It also best-in-class oncologists who take a patient-centered approach to diagnosis and treatment.
“I think we want to be impactful in a couple ways — we want to be able to screen the patients who are at high risk and make it more equitable,” he says.
If you or a loved one is concerned about possible signs or symptoms of cancer and would like an initial appointment or a second opinion, call us 24/7 at (877) 834-8941.