Air pollution’s affect on your lungs is pretty obvious. Go out running on a Code Purple air quality day and you’ll come home thirsty, coughing and tired (so please don’t). Air pollution, especially particulate matter, also messes with your heart, affecting its electrical system and potentially causing or exacerbating heart disease.

But it turns out air pollution might have even subtler — and more disturbing — ways of upending your health. Building off observations that the tissue and blood of lung cancer patients sometimes shows altered gene programming as a result of a chemical transformation called methylation, researchers out of the University of Milan did an experiment of their own. They found that certain particulates cause the reprogramming of genes — changes that can lead to the development of cancer and other diseases.

According to ScienceDaily, researchers took blood DNA samples from 63 healthy foundry workers near Milan, Italy, at the beginning of the work week.