Young men who go out at night with romance in their hearts and condoms in their wallets should find another storage place, medical researchers say. Ozone, a major component of smog and a product of lightning storms, damages the latex in condoms, and any practice threatening to tear condoms' packaging and expose them to air should be avoided, the researchers said. ``It's not something you should subject to putting in your back pocket, or sitting on, or in any way damaging,'' said Russell P. Sherwin, a researcher at the University of Southern California School of Medicine in Los Angeles. Ozone is a lung irritant produced when industrial pollutants and nitrogen oxide react in the presence of sunlight. It reaches high levels in U.S. cities inhabited by a total of 75 million people, the federal Environmental Protection Agency estimated earlier this year. U.S. sales of condoms _ fueled in part by U.S. Surgeon General C. Everett Koop's endorsement as protection against AIDS _ totaled $290 million last year and should jump 20 percent more this year, market analysts have said. Sherwin and fellow researchers tested 20 unrolled, unpackaged latex condoms, exposing them to air containing 0.3 parts per million of ozone for 72 hours, a level comparable to a ``Stage 1'' smog alert in Southern California. Afterward, all but two condoms had obvious holes in them and 11 burst at pressures far below those that condoms unexposed to ozone-containing air were able to withstand, the researchers said. Examination of the ozone-exposed condoms with an electron microscope also revealed deterioration, the researchers reported in a letter in Friday's Journal of the American Medical Association. ``The effect on latex of 0.3 parts per million of ozone for 72 hours is serious and deserves consideration for all phases of condom storage, including the storage and dispersion of non-packaged condoms by sexually transmitted disease prevention and family planning clinics,'' the researchers wrote. Sherwin said in a telephone interview Wednesday, ``The package seemed to provide protection as long at it was intact, as long as it wasn't perforated or crinkled.'' He said the researchers are continuing studies and plan to issue formal findings, including whether another common pollutant _ nitrogen dioxide _ can penetrate typical condom packaging, as it does other kinds of packaging, and cause condoms to become faulty even when unopened. ``The general advice that we offer on condoms holds,'' said Dr. Robert Staab, vice president of scientific affairs for Schmid Laboratories Inc., the nation's No. 2 condom-maker behind Carter Wallace Inc. of New York. ``That is that they are going to remain safe and effective for a normal life of a product, which is in years, as long as you keep them away from heat, light and ozone,'' Staab said Thursday from the company's Little Falls, N.J., headquarters. The company's packaging is designed partly with ozone in mind by choosing ``only raw materials that will seal properly'' to keep out heat, light and ozone, Staab said. Schmid makes Ramses, Sheik and Koromex latex brands and Fourex natural skins brands, but the researchers declined to identify any of the brands of condoms involved. Natural skins condoms also are susceptible to damage from exposure to the environment, Staab added. Recent recalls of several condom lots have increased concern about their dependability, the California researchers said. ``Our general advice is if upon opening a condom and it doesn't look right, don't use it,'' Staab said.