It's a classic behavior: puffing from a cigarette makes many girls and boys feel hotter.

But in reality, smoking is proven to make you look older and not really glamorous.

A new research from the University of Michigan Health System comes with new data on the connection between cigarette smoking and skin aging.

The study shows that smoking inflicts a higher degree of aging even on skin areas which are not normally exposed to sunlight, like the inside of the upper arm. "We examined non-facial skin that was protected from the sun, and found that the total number of packs of cigarettes smoked per day and the total years a person has smoked were linked with the amount of skin damage a person experienced," said Dr. Yolanda R. Helfrich, lead author and assistant professor of dermatology at the U-M Medical School.

The team made a photonumeric scale which can be easily employed by other medical institutions too, to assess the aging level on patients' skin. The researchers applied their nine-point scale on photographs of the inside-upper-arm skin of the 77 volunteers.

Three researchers investigated the images and assigned grades, zero meaning no fine wrinkling and eight representing severe fine wrinkling.

The same team reviewed photos of the volunteers one year later, and by comparing the scores, they could assess the increase in the skin damage.

The team also introduced in their results data like subjects' age, ethnicity, history of cigarette smoking, use of non-steroidal anti-inflammatory drugs, use of dietary or herbal supplements, sun exposure, sunscreen use, tanning bed use and, for women - the number of children they had, hormone therapy use and oral contraceptive use.

The subjects were current or former smokers, with an average smoking period of about 24 years. Among subjects who were 45 years or older, skin aging was found to be much higher in smokers than in nonsmokers. In the 45-65 age category, smokers displayed an average score of more than two on the photonumeric scale, while nonsmokers presented an average score of less than one.

In those older than 65, smokers score on average about six on the scale, while nonsmokers' average score was roughly four.