Air pollution drives lung cancer mutations in never-smokers, study finds

A global study of nearly 900 people who developed lung cancer without ever smoking has uncovered a troubling mechanism: air pollution drives the same cancer-causing DNA mutations that tobacco smoke does. The research, published in Nature, examined the complete genetic code of tumors removed from 871 never-smokers across Europe, North America, Africa, and Asia, and found a direct correlation between regional air pollution levels and the presence of cancer-promoting mutations in their cells.

The pattern emerged clearly in the data. Fine-particulate air pollution was particularly linked to mutations in the TP53 gene—a mutation signature long associated with smoking. Researchers also discovered that people exposed to higher pollution had shorter telomeres, the protective caps at the ends of chromosomes that typically shorten with age. Premature shortening signals accelerated cell division, a hallmark of cancer development. "Our research shows that air pollution is strongly associated with the same types of DNA mutations we typically associate with smoking," said Prof Ludmil Alexandrov of the University of California in San Diego, one of the study's senior authors.

This finding addresses a puzzle that has been growing more urgent. As smoking rates have declined in developed nations including the UK and the US, a paradox has emerged: the proportion of lung cancer cases occurring in never-smokers has risen. Today, between 10 and 25 percent of all lung cancer diagnoses occur in people who have never smoked. Almost all of these cancers are adenocarcinoma, a form typically found in the outer regions of the lungs. Lung cancer remains the leading cause of cancer-related death worldwide, with approximately 2.5 million new cases diagnosed each year. More than a million of those deaths occur in China, where smoking, air pollution, and other environmental contaminants converge as major risk factors.

The geographic distribution of the disease tells its own story. East Asia carries the highest burden of adenocarcinoma attributable to air pollution. In the UK, where air quality is generally better than in many parts of the world, researchers still identified more than 1,100 new diagnoses each year linked to pollution exposure. The scale suggests this is not a marginal problem but a significant public health threat operating in the background of everyday life.

The study also uncovered other culprits. Secondhand tobacco smoke showed only a slight association with increased cancer-causing mutations. But certain Chinese herbal medicines containing aristolochic acid emerged as a notable risk factor, with signature mutations from these medicines appearing almost exclusively in never-smokers from Taiwan. Researchers also identified another mysterious mutational signature present in never-smokers but absent in smokers—a pattern now under intense investigation, according to Dr Maria Teresa Landi, an epidemiologist at the US National Cancer Institute in Maryland.

The implications are stark. As Landi framed it, this represents "an urgent and growing global problem that we are working to understand." The research does more than document a trend; it provides a biological explanation for why people breathing polluted air face cancer risk comparable to smokers. The findings suggest that environmental exposure, not personal behavior, may be driving a significant portion of lung cancer cases in populations with no smoking history—a reality that demands attention from public health authorities and policymakers worldwide.