Live in a smoggy city — or just visited one for a few days? A new study suggests that polluted air can change our DNA in just three days, increasing your chance of getting cancer and other diseases.

The downer news comes from a study that looked at the DNA of steel-foundry workers in Brescia, Italy, who were exposed to particulate matter — teensy pieces of soot, dust and metal in the air — similar to those found in “normal air” in cities.

How does this DNA change occur? The process is complicated. National Geographic describes it thusly:

Exposed workers’ DNA was damaged by a slowed rate of “methylation,” a biological process in which genes are organized into different chemical groups.

Fewer groups means that fewer genes are expressed — or made into proteins — a crucial process in the body’s regular maintenance.

The researchers behind the study say that more study is still needed — but we don’t need to wait for confirmation to start cleaning up our air. The American Lung Association’s recommended steps to clean up the air in your neighborhood are: “drive less; don’t burn wood or trash; use less electricity; and make sure local school systems require clean school buses."

The opinions expressed by MNN Bloggers and those providing comments are theirs alone, and do not reflect the opinions of While we have reviewed their content to make sure it complies with our Terms and Conditions, MNN is not responsible for the accuracy of any of their information.