Lung cancer accounts for most cancer deaths. Smoking poses a big risk of lung cancer, and with more cigarette smoking comes higher health risks. Abstaining from cigarette smoking is always helpful in preventing lung cancer. In early stages, the bad effects of smoking are reversible. Tobacco fumes have been linked to carcinogenic effects; cigarette smoking speeds up the development of lung cancer. Apart from cancer, smoking has other bad effects like chronic cough, laryngitis, sinusitis, and bronchitis. The factors that contribute to the development of lung cancers are called risk factors: Passive smoking or secondhand smoke also carries such a risk factor for lung cancer. Cigar and pipe smoking have similar effects like that of cigarette smoking, but they are not as dangerous.
 

Apart from smoking, some other risk factors have carcinogenic effects on lungs. Exposure to asbestos and radon gas, air pollution, and other lung disorders have carcinogenic effects.
 

People occupationally exposed to asbestos are at risk of developing lung cancer and other lung disorders. The asbestos fibers get trapped into lung tissues and cause irritation. Asbestos exposure has two harmful effect — lung cancer and mesothelioma (cancer of pleural membrane).
 

Radon gas exposure is also a risk behind the development of lung cancer. Radon gas decomposes to form some products that can emit radiation, causing side effects like cancer of the lung.

In metro cities, air pollution is also a cause of lung cancer. Vehicles, industries, and power plants emit toxic elements, causing air pollution. A number of studies have set out to ascertain the effects of air pollution. Some known bad health effects of air pollution are cancer, asthma, chronic obstructive pulmonary disease, heart failure, and premenopausal breast cancer.  
 

The World Health Organization has declared air pollution a carcinogen just like tobacco. The WHO considers air pollution as one of the leading causes of death from cancers in the world. Apart from lung cancer, air pollution increases the risk of bladder cancer. Disastrous effects of air pollution can be established by the fact that the survival rate of patients with lung cancer caused by air pollution is very low.

Studies reveal that people with chronic obstructive airway disease like chronic bronchitis and emphysema are at increased risk of developing cancer of the lung.

Family history of lung cancer increases the risk of cancers of the lung. Certain genetic predispositions are seen in cases of lung cancer.