There are a few factors that lead to lung cancer. Some of the most common reasons are:

1. Cigarette smoking: It is a very common factor. There are people who are addicted to cigarette smoking and some even smoke two packs or more per day. Out of every seven people, at least one person would develop lung cancer. Folks who smoke about one pack of cigarettes per day are prone to this threat 25 times more than non-smokers. People who casually smoke are also not free from this, as they could also develop lung cancer. Smoking damages the cells. The moment you quit smoking the damaged cells start repairing themselves and become healthy cells. So, it is advised to give up smoking altogether.

2. Secondhand smoking: it is also known as passive smoking because you tend to inhale smoke without actually holding a cigar or a pipe between your lips. The people who are exposed to this kind of smoking have 24% chances of developing lung cancer. About 3000 deaths are estimated in a year due to secondhand smoking.

Asbestos Exposure: Asbestos causes lung cancer and mesothelioma known as the cancer in the linings of the pleural sheet. It separates the silica fibers that are trapped in the tissues of the lungs. If you have been a smoker or if you smoke even now, then the possibility of contracting this disease is high. The risk is about 50 to 90 percent more than non-smokers.

Radon Gas: radon is a gas that is colorless and odorless that is released from decayed uranium. As per the analysis done by the U.S. Environmental Protection Agency, almost 15% of the homes are exposed to radon and every year about 15,000 to 22,000 deaths occur.

Air pollution: if you inhale polluted air for a long period of time then you are most likely to develop cancer. About 1% of the total lung cancer deaths are due to this problem.