Environment and the Skin

Traffic-related air pollution causes age spots on the face

A large scale study that included women from Germany and China has demonstrated a link between levels of traffic-related air pollution and air pollution- associated gases with the formation of dark spots on the skin, known as lentigenes. The most pronounced changes were observed on the cheeks of Asian women over the age of 50. The report was published in the Journal of Investigative Dermatology.

Two groups were studied. The first included 806 Caucasian German women who ranged in age from 67 to 80 years. Twenty percent had a history of smoking. These women reportedly spent an average of 2.6 hours a day in the sun. The second group included 743 Han Chinese women from the Taizhou region who were somewhat younger than the German group, ranging in age from 28 to 70 years. Twenty percent of this group also had a history of smoking. Reported average daily sun exposure for this group was 3.5 hours. Many more of the German women reported using cosmetics with sun protection (61%) compared to the Chinese women (4.2%).

Nitrogen dioxide, or NO2, is part of a group of gaseous air pollutants produced as a result of road traffic and other fossil fuel combustion processes. Its presence in air contributes to the formation and modification of other air pollutants, such as ozone and particulate matter, and to acid rain. In this study, an association was seen between levels of NO2 and the formation of dark spots (lentigenes) on the back of the hands and forearms of the study subjects, and exposure to NO2 was significantly associated with more dark spots developing on the cheeks in both German and Chinese women older than 50 years.

Lentigenes, also known as liver spots, are small, darkened areas of the skin. Although they might first appear small, they might enlarge, and separate patches might merge. They are most commonly found on the face, forearms, hands, and upper trunk. Usually brown in color, lentigenes can appear yellow-tan to black. Lentigenes are more common in light-skinned individuals, and in the United States, solar (sun- associated) lentigenes are noted in 90 percent of Caucasians older than 60 years and 20 percent of those younger than 35 years. Lentigenes, which contain an increased number of the melanin-forming cells of the skin (melanocytes), are generally benign, although some forms may be pre-cancerous.

SOURCE: Hüls, et al. Traffic-related air pollution contributes to development of facial lentigines: further epidemiological evidence from Caucasians and Asians. J Invest Dermatol. 2016;136(5,):1053–1056.

Exposure to ground ozone increases UV damage to our skin.

Research is showing that exposure to ground-level ozone might be associated with increased facial wrinkles, even without sun exposure, but also increases the damage caused by UV exposure. Ground level ozone is the accumulation of gaseous emissions from cars and chemical plants. NO2 and organic compounds in these emissions interact with sunlight to become highly reactive. Evidence confirms that this exposure is very damaging to the skin and can cause premature skin aging and increased skin sensitivity. Regular contact with ozone depletes antioxidants from the also increases damage to key fats (lipid peroxidation) and proteins (protein oxidation) in the skin, which suggests there are multiple ways that daily contact with ground-level ozone and soot (a mixture of carbon particles and organic compounds) can deplete our defenses and increase the damage that UV exposure does to our skin.

SOURCES: 1) Friedman A. Sunlight and pollution: a dangerous combination for our skin. HuffPost site. October 31, 2016. http://www.huffingtonpost.com/adam-friedman- md-faad/sunlight-and-pollution-a-_b_12693108.html. Accessed September 1, 2017; 2) Thiele JJ, et al. Ozone-exposure depletes vitamin E and induces lipid peroxidation in murine stratum corneum. J Invest Dermatol. 1997;108(5)753–757.

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