Researchers at the University of Alabama at Birmingham revealed that drinking alcohol while being exposed to tobacco smoke is more dangerous than being exposed to smoke alone.

The test conducted by Scott Ballinger based on exposing mice in an enclosed laboratory to smoky air and feeding them a liquid diet containing ethanol – the substance that makes people intoxicated. These mice had an almost five-fold increase in artery lesions than the mice that breathed filtered air and had a normal solid diet. Heavy smokers have more chances to suffer from artery lesions and to further develop cardiovascular disease, according to Ballinger.

The study shows that exposure to cigarette smoke while drinking alcohol caused greatest degree of cardiovascular disease development compared to being exposed to either smoky air or alcohol.

“Because moderate alcohol consumption is commonly thought to be cardioprotective, these findings are important for smokers and non-smokers alike in terms of what you should and should not do to protect their health,” said Shannon Bailey, an associate professor in the UAB Department of Environmental Health Sciences and a co-investigator on the study, in a news release.

The experiments were performed for a period of five weeks, cigarette exposure was similar to being in a vehicle with a chain smoker inside and the windows closed and the blood concentration in the mice equaled a 150-pound adult consuming two drinks per hour.

The study is published in the journal Free Radical Biology & Medicine.