LONDON - Air pollution can cause lung cancer in people who have never smoked by “waking up” dormant cancer cells, scientists have found.

There are 35,000 deaths from lung cancer in the UK every year; about 6,000 are in people who have never smoked.

After a decade of research, a team at the Francis Crick Institute and University College London have solved the mystery of why many non-smokers develop cancer, examining a type of the disease that commonly affects them: epidermal growth factor receptor (EGFR) mutant lung cancer.

While tobacco directly mutates the DNA in healthy cells, tiny PM2.5 pollutants from traffic fumes cause inflammation that activates cells which carry cancerous mutations, which are found in everyone, but usually remain harmless.

The study, funded by Cancer Research UK, examined data from more than 400,000 people from the UK, South Korea and Taiwan, and found higher rates of cancer in regions with high air pollution.

The discovery could ultimately help to find better ways to prevent and treat lung cancer in people who have never smoked.