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.