Understanding the risk factors for lung cancer

Lung cancer remains the deadliest form of cancer worldwide. A crucial step toward prevention involves understanding the main risk factors for lung cancer. These include harmful habits, environmental substances, and certain health conditions. Below, we outline the most significant risk factors, ranked in order of importance.

Smoking: the leading cause

Smoking represents the number one risk factor for lung cancer. Studies indicate that in the United States, smoking accounts for roughly 80% of all cases. Cigarette smoke contains many chemicals that can cause inflammation and infection, eventually leading to cancer. The longer and more heavily a person smokes, the greater their risk becomes.

It is also important to note that exposure to secondhand smoke significantly increases lung cancer risk among non-smokers.

Age and lung cancer risk

Although lung cancer is rare among young adults, the risk increases markedly with age. Older adults face a higher probability of developing the disease.

Radon exposure

Radon, a colorless and odorless radioactive gas, poses a serious environmental health threat. When inhaled, it damages lung cells and can cause cancer. While generally low outdoors, radon can accumulate to hazardous levels in poorly ventilated indoor spaces. In fact, radon is the second most common cause of lung cancer overall, and the top cause among non-smokers in the U.S.

Asbestos and industrial exposure

Industries such as construction and manufacturing have historically used asbestos. Inhaling its tiny fibers over time can lead to chronic lung irritation, scarring, and eventually cancer. People exposed to asbestos face elevated risks for lung cancer and other respiratory diseases.

Harmful chemical agents

Exposure to certain chemicals—including formaldehyde, silica, beryllium, cadmium, and chromium—can increase an individual’s likelihood of developing lung cancer.

Outdoor air pollution

Toxic particles and chemicals in polluted air harm respiratory health. Global studies estimate that around 5% of lung cancer deaths relate to outdoor air pollution.

Personal or family history of cancer

A personal or family history of cancer can elevate an individual’s risk of developing lung cancer. Those with close relatives who had cancer should be especially mindful.

Personal history of lung diseases

Chronic lung diseases—such as COPD, tuberculosis, chronic bronchitis, asthma, or pulmonary fibrosis—damage lung tissue and are associated with higher cancer risk.

Indoor air pollution

In addition to radon, indoor activities like burning coal or frying food at high temperatures can release carcinogenic particles into the air, further contributing to lung cancer risk.