People who live in towns/cities have much higher risks to acquire lung cancer compared to those who live in the mountains. The air people breathe is one of the most common reasons for this disease besides smoking, smog, genetics, or working in a mine. The air is thicker in the lowlands which means richer oxygen. It has great benefits, but is also dangerous, because oxygen is an unusual element and when we eat, our body use it to transform the food into energy. Oxidation is a metabolic process that helps the body release free radicals that are very carcinogenic. The atoms have the power to make a real chaos in the organism, damaging the DNA and mutate the cells, causing cancer.
This is a natural process, but if you want to decrease the risk of acquiring the disease, move to a higher altitude above sea level. Mountains are the best because of the air is thinner making lungs spread more and work in a different way as well as they have less dangerous oxygen with which they have to fight.
There was a great research conducted by American scientists where they calculated that on every 1000 meters of altitude above the level of the sea, the number of people who acquire lung cancer decreases multiple times.