Environmental Causes of Lung Cancer

Smoking is not the only cause of lung cancer. In addition to cigarette smoke, there are many environmental agents known to increase the risk of the disease. As with smoking, many of these environmental risks can be avoided or reduced once you're aware of them, such as hazardous chemicals found in the home or workplace, particle pollutants in the air, exposure to radiation, and secondhand smoke from people you live or work with.

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Radon is a radioactive gas produced by the natural decay of uranium in the soil. Exposure to radon in the home is the second-leading cause of lung cancer in the United States as well as the leading cause in non-smokers.

Radon is found throughout the world and can enter homes through cracks in the foundation, via sump pumps and drains, and through gaps around pipes and wires. No fewer than one of every 15 American homes is believed to have elevated and potentially hazardous radon levels.

The Environmental Protection Agency (EPA) suggests that around 21,000 Americans get lung cancer from radon exposure each year.

You can test your home by using a simple do-it-yourself radon testing kit (available at most hardware stores for about $20 to $30). If the test is strongly positive, a professional clean-up process called radon mitigation can almost always return your home to safe levels.

Secondhand Smoke

Secondhand smoke is responsible for around 2% of lung cancer deaths in the United States, or approximately 7,300 deaths per year.

According to the Centers for Disease Control and Prevention (CDC), tobacco smoke contains around 7,000 toxic chemicals, 70 of which are known or suspected carcinogen. Secondhand exposure to these chemicals increases a non-smoker's risk of lung cancer no less than two- to three-fold.

Even though no-smoking laws have greatly reduced the risk of exposure in public places, you still need to make an extra effort to avoid secondhand smoke at home or at social gatherings if you're not a smoker.

If you are a smoker, find a way to quit cigarettes if you live with others who do not smoke. There is no such thing as a "safe" amount of secondhand smoke.


Asbestos is a mineral-based substance long used for insulation that has been banned in the United States for several decades due to its link to different cancers, including mesothelioma.

If left undisturbed, asbestos poses little risk to your health. If disturbed, particles can be released into the air that are easily inhaled. This can cause adverse changes to the lining of the lungs, called the pleura, and increase the risk of lung cancer over time.

Asbestos is ordinarily considered an occupational hazard, but it can also be found in homes built pre-1970 (before asbestos was officially banned under the Clean Air Act).

If you choose to remodel an older home that may contain asbestos insulation, hire a certified contractor who can check for asbestos beforehand and remove it safely.

Air Pollution

In the United States, air pollution is believed to contribute to around 5% of lung cancers in men and 3% in women. In parts of Europe, as many as 10% of cases are directly associated with atmospheric pollutants. In China and parts of East Asia, the rate may be as high as 50%.

Among some of the carcinogens commonly found in air pollution are benzene, sulfur dioxide, diesel engine exhaust, formaldehyde, and coal ash.

If you live in a high-density urban area, keep an eye out for air-quality warnings on the news. Stay indoors if a warning has been issued, shutting all doors and windows. If you need to go outside, consider wearing a face mask.

Industrial Chemicals

As with asbestos, exposure to carcinogenic chemicals can sometimes occur in the workplace. To reduce the risk of exposure, employers in the United States are required to provide employees with Material Safety Data Sheets. These outline all of the hazardous agents used on the premises and ways to reduce the risk of exposure by using protective gear and safety measures.

Common industrial carcinogens include:

  • Arsenic
  • Cadmium
  • Coke oven fumes
  • Chromium compounds
  • Coal gasification
  • Nickel refining
  • Foundry substances
  • Soot
  • Tars
  • Oils
  • Silica 

But work is not the only place where chemical exposure occurs. Many chemical strippers and solvents available at local hardware stores also contain these same ingredients, albeit in lower concentrations.

To reduce your risk of harm, always read product labels of any solvent or stripper you buy. Heed the safety warnings and adhere to the proper use of the product. This may include wearing gloves, ensuring good ventilation, and putting on a face mask or respirator to avoid inhaling fumes.

Wood Smoke

Exposure to wood smoke may increase the risk of lung cancer. The risk tends to be highest in people exposed to smoke from wood-burning stoves and fireplaces for many years. Many of those at risk rely on solid fuels like wood, coal, and charcoal for cooking and heat. Those responsible for cooking in such environments—frequently women—are at higher risk.

According to the World Health Organization (WHO), no less than three billion people worldwide rely on solid fuels for cooking and heating. In total, around 17% of lung cancers can be attributed to the burning of these solid fuels.

To reduce your risk, you might consider converting your wood fireplace to gas (whether you use it for cooking or just ambiance). You should also ensure good ventilation if ever heating with or cooking over a wood or charcoal fire. While a little smoke likely won't do you harm, no one knows for sure how much is "safe" or "unsafe."

Radiation Therapy

While you might not immediately think to lump it into this group, chest radiation for medical purposes is an environmental exposure that can increase the risk of lung cancer. Examples include radiation therapies used to treat Hodgkin’s lymphoma (HL) or breast cancer.

Though bladder and rectal cancers are the most common secondary malignancies linked to radiation therapy, lung cancer has also been known to occur. The risk is highest in people treated for HL who are moderate-to-heavy smokers. By contrast, non-smokers treated with radiation for HL have a five-fold decreased risk of lung cancer.

Despite the risk, the benefits of radiation therapy generally outweigh the risks. If you are undergoing radiation therapy and are a heavy smoker, let your doctor know and seek help to quit.

If you smoke or have quit within the past 15 years, you may be a candidate for annual lung cancer screening, which is performed with a computerized thermography (CT) scan. The other criteria for screening are age (between 50 and 80) and a 20 pack-year or more history of smoking.

By monitoring the lungs on an ongoing basis, high-risk individuals are more likely to catch cancer early while it is still treatable.

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