A full 15 percent of diagnosed lung cancer patients have never used tobacco products a day in their lives—in other words, they are people who don’t smoke but still got lung cancer. While it speaks well of the public education campaigns that we associate cigarettes, cigars, and pipes with the development of lung cancer, they are not the only cause, according to Roswell Park Comprehensive Cancer Center.

How Does the Incidence of Lung Cancer Rate Among Cancers?

Because lung cancer is the top killer among cancers, people who don’t smoke as well as people who do are subject to its ravaging effects. Annually, lung cancer takes more lives than the combined death statistics of breast, prostate, and colon cancers, according to the Roswell Park report.

What Are the Primary Causes of Lung Cancer Among People Who Don’t Smoke?

Second-Hand Smoke

While we don’t always know the etiology of cancer in a person—sometimes, the disease process is a mystery all to itself—there are certain environmental hazards that are definitely part of a pattern. The first cause would be second-hand smoke. Those individuals who live with a smoker and inhale the smoke in the air as part of their daily living conditions are particularly at risk.

Second-hand smoke exposure can occur in childhood and set the stage for later development of lung cancer, whether or not previous exposure as an adult has happened. Another source of second-hand smoke which has been legally addressed in the U.S. is within and around the entrances to office and other commercial buildings.

Asbestos Exposure

According to the American Cancer Society (ACS), both of the two main types of asbestos fibers have been linked to cancer; chrysotile and amphibole. While asbestos exposure is most commonly associated with a particular type of cancer known as mesothelioma—one which affects the lining of the lungs, heart, abdominal cavity, and testes—inhaling or swallowing asbestos has been known to produce generalized lung cancer and other diseases.

Radon Gas

ACS also points out that radon gas exposure contributes to 21,000 deaths from lung cancer each year. Thought the number seems small compared to the 480,000 deaths expected from tobacco use-based lung cancer, exposure to the gas is still of concern.

Radon gas can’t be detected without being specifically tested for in a home as you can’t smell or taste it. It is caused by the disintegration of uranium in soil and rocks beneath the foundation of a house and can leak in if pipe gaps and crawl spaces are not properly secured. Radon exposes the body to doses of radiation over time.

Occupational Exposure

As indicated by VeryWellHealth.com, there are multiple occupations where workers are exposed to chemicals, diesel and other fumes, as well as asbestos. A few of these occupations include railroad work, masonry, sandblasting, rubber production, glass manufacturing, printers, aluminum production, uranium and coal mining, metal work, and others. Exposure to these substances can increase the risk of lung cancer.