The more traffic-related air pollution in a woman’s life, the more likely she is to develop brown spots on her face. Researchers from Dusseldorf, Germany identified nitrogen dioxide (NO2) concentrated in traffic-related air pollution as a causative factor in the development these brown spots, popularly known as liver spots. Exposure to NO2 is also associated with lung cancer and compromised lung function. The researchers studied two groups of women - 806 German women ranging in age from 67 to 80 and 743 Han Chinese women ages 28 to 70. The investigators found no link between levels of NO2 and liver spots (known medically as lentigines) on the back of the women’s hands or forearms, but observed a significant link between exposure to NO2 and brown spots on the cheeks of women older than age 50 in both groups. This was particularly evident in the Chinese women over 50. In general, liver spots usually appear on the face, forearms, hands and upper trunk. In the U.S. 90 percent of Caucasians older than age 60 and 20 percent of those under 35 have these brown spots, which are considered benign, as a result of sun exposure.