Non-smokers who live in areas with high pollution are 20 percent more likely to develop lung cancer compared to people who live in cleaner areas, a new study concludes.
“Lung cancer in 'never smokers' is an important cancer. It's the sixth leading cause of cancer in United States,” study’s lead author, Michelle Turner, a graduate student at the University of Ottawa, said.
While air pollution has long been considered a risk factor for lung cancer, its impact apart from that of smoking was not clearly known. Cases of non-smokers’ being diagnosed with lung cancer range from 14 to 21 in every 100,000 women and five to 14 in every 100,000 men, researchers highlighted.
To gauge the incidence of lung cancer in non-smokers, researchers at the University of Ottawa enrolled over 180,000 non-smokers living in all 50 states and in Puerto Rico. The participants were followed for over two and a half decades.
Using the zip codes of the areas where the participants resided, the researchers estimated the levels of air pollution they were exposed to. The participants’ exposure was measured in units of micrograms of particles per cubic meter of air, with average air pollution levels of 17 units across the study period (21 units in 1979-1983 and 14 units in 1999–2000).
Findings of the study
During the 26 years study span, 1,100 people died from lung cancer.
For every 10 extra units of air pollution a person was exposed to, his risk of lung cancer rose by 15 to 27 percent, researchers revealed. The estimates took into account other cancer risk factors, such as second-hand smoke and radon exposure.
“The increased risk of lung cancer is nevertheless minute in comparison to the 20-fold increase in risk from smoking,” Turner remarked.
While the findings of the study did not explicitly link air pollution with lung cancer, “there's lots of evidence that exposure to fine particles increases cardiopulmonary mortality,” Turner told Reuters Health. “Fine particles in air pollution can injure the lungs through inflammation and damage to DNA.”
The findings of the study are published in the American Journal of Respiratory and Clinical Care Medicine.