London, Feb 9 (IANS): Have you observed formation of dark spots on the cheeks of women over the age 50? A new study has revealed a link between traffic-related air pollution and air pollution-associated gases with the formation of dark spots on the skin of women.

"In addition to particulate matter, traffic-related air pollution is characterised by increased concentration of nitrogen dioxide (NO2)," said lead author Jean Krutmann IUF-Leibniz Research Institute for Environmental Medicine, Dusseldorf, Germany.

"While NO2 exposure is known to be associated with low lung function and lung cancer, the effect of NO2 on human skin has never been investigated. This is important because environmentally-induced lung and skin aging appear to be closely related," Krutmann added.

Lentigenes, also known as liver spots, are small, darkened areas of the skin. Although they may first appear small, they may enlarge and separate patches may merge on the face, forearms, hands, and upper trunk.

For the research, published in the Journal of Investigative Dermatology, two groups were studied.

The first group included 806 Caucasian German women ranging 67 to 80 years. These women reportedly spent an average of 2.6 hours a day in the sun.

The second group included 743 Han Chinese women with an age ranging 28 to 70 years. These women spent average daily sun exposure of 3.5 hours.

The study found, no association was seen between levels of NO2 and lentigenes' formation on the back of the hands or forearms, however, exposure to NO2 was significantly associated with more lentigenes on the cheeks in both German and Chinese women older than 50 years.

NO2 gas had a slightly stronger effect than the particulate matter concentration that had a greater impact on dark spot formation, according to the research.