Lung Cancer and Air Quality

The main causes, in order

The American Lung Association says lung cancer happens when cells in the lung mutate, most often after people breathe in dangerous, toxic substances, and that the risk can remain even if the exposure was many years ago.^[2]

1. Smoking. The American Lung Association calls smoking the number one cause of lung cancer, responsible for about 90 percent of cases. Breathing secondhand smoke also puts people who have never smoked at risk.^[2]
2. Radon. The EPA estimates radon is the number one cause of lung cancer among non-smokers and the second leading cause overall. It is responsible for about 21,000 lung cancer deaths each year, about 2,900 of them among people who have never smoked.^[3] A smoker who is also exposed to radon has a much higher risk.^[3]
3. Hazardous chemicals at work. The American Lung Association names asbestos, uranium, arsenic, cadmium, chromium, nickel and some petroleum products as especially dangerous to work with.^[2]
4. Particle pollution. The American Lung Association says evidence shows particle pollution, like exhaust smoke, increases the risk of lung cancer.^[2] It lists a higher likelihood of getting lung cancer among the effects linked to year-round particle exposure.^[4]

Genes also play a role: a family history of lung cancer may mean a higher risk, which is worth mentioning to your doctor.^[2]

Outdoor air pollution and cancer

The National Institute of Environmental Health Sciences (NIH) notes that in 2013 the World Health Organization's International Agency for Research on Cancer classified air pollution as a human carcinogen. It also describes a 2000–2016 study that found an association between lung cancer incidence and greater reliance on coal for energy.^[5]

The daily AQI covers ozone, particle pollution, carbon monoxide, sulfur dioxide and nitrogen dioxide.^[1] It doesn't measure radon, which builds up indoors, so the only way to know your home's level is to test it.

Radon: test your home

Radon is a colorless, odorless radioactive gas that occurs naturally in soil and enters buildings through small gaps and cracks. The American Lung Association says about one in every 15 U.S. homes is subject to radon exposure, and recommends testing with an inexpensive, easy-to-use kit.^[2]

The EPA's risk chart sets these action levels:^[3]

• 4 pCi/L or higher: fix your home.
• 2 to 4 pCi/L: consider fixing.
• About 1.3 pCi/L: the average indoor radon level.

Our radon guide explains testing and mitigation in more detail.

If you have lung cancer

The American Lung Association includes people with lung cancer among the groups at higher risk from particle pollution.^[4] On days when the AQI is in the orange range or higher, sensitive groups may experience health effects.^[1] Ask your oncology team how to adjust outdoor activity on those days.

What the AQI colors mean

AirNow reports the Air Quality Index (AQI) for five pollutants regulated under the Clean Air Act: ground-level ozone, particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide and nitrogen dioxide.^[1]

• Green, 0–50 (Good): air pollution poses little or no risk.^[1]
• Yellow, 51–100 (Moderate): acceptable, but there may be a risk for people who are unusually sensitive to air pollution.^[1]
• Orange, 101–150 (Unhealthy for Sensitive Groups): members of sensitive groups may experience health effects; the general public is less likely to be affected.^[1]
• Red, 151–200 (Unhealthy) and above: some members of the general public may experience health effects, and sensitive groups may experience more serious effects.^[1]

Check today's reading for your area on the city air quality pages or at AirNow.gov.