Washington, Nov 19 (ANI): While bans on indoor smoking have forced smokers at bars and restaurants onto outdoor patios, researchers have now raised concerns over the increasing exposure to second-hand airborne smoke.

They assessed the levels of a nicotine by-product known as cotinine in nonsmokers exposed to second-hand smoke outdoors and found levels up to 162 percent greater than in the control group.

Indoor smoking bans have helped to create more of these outdoor environments where people are exposed to secondhand smoke, said study co-author Luke Naeher, associate professor in the UGA College of Public Health.

We know from our previous study that there are measurable airborne levels of secondhand smoke in these environments, and we know from this study that we can measure internal exposure, said Naeher.

Secondhand smoke contains several known carcinogens and the current thinking is that there is no safe level of exposure, he added. So the levels that we are seeing are a potential public health issue.

During the study, researchers recruited 20 non-smoking adults and placed them in one of three environments: outside bars, outside restaurants and, for the control group, outside the UGA main library.

Immediately before and after the six-hour study period, the volunteers gave a saliva sample that was tested for levels of cotinine, a byproduct of nicotine and a commonly used marker of tobacco exposure.

They found an average increase in cotinine of 162 percent for the volunteers stationed at outdoor seating and standing areas at bars, a 102 percent increase for those outside of restaurants and a 16 percent increase for the control group near the library.

Our study suggests that there is reason to be concerned about second-hand smoke levels outdoors and our findings are an incentive for us to do further studies to see what the effects of those levels are, said study co-author Gideon St. Helen, who is pursuing his Ph.D. through the university's Interdisciplinary Toxicology Program.

The study appears in the Journal of Occupational and Environmental Hygiene. (ANI)