If you value your complexion, Salt Lake City may not be the best place to live, according to a new study.

Salt Lake City ranks fourth behind Phoenix, Denver and Sacramento in terms of those city's least conducive to youthful skin, according to the findings in a study commissioned by Collagen Corp. of Palo Alto, Calif.Phoenix won its dubious honor by having mostly hot, clear days with low humidity. Cloudy Portland, Ore., topped the list among large cities as having the best environment for complexion.

"Really the worst (factor) was the sun exposure," said Dr. Robert Vitolo, a New York City plastic surgeon who participated in the survey, "That's what got Phoenix. They have the greatest number of days of sun for any of the cities, which is great if you're a travel agent.

"Phoenix has a combination of two things: number of days of sun and the altitude. The higher you get, the stronger the ultraviolat rays are. Basically it all revolves around creating wrinkles," Vitolo said in an interview.

Portland, known for its abundant rain, has sunshine less than 50 percent of the time on the average, along with high humidity, low altitude and little wind, the commission pointed out.

Denver, higher in elevation than Phoenix but having more cloudy days, came out second-worst for city climates that encourage premature aging of the skin, followed by Sacramento, Calif.; Salt Lake City; Los Angeles; San Francisco; Dallas; Miami; San Diego; and San Jose, Calif.