The health hazards of smoking cigarettes are familiar to virtually all of us, as are the negative consequences of secondhand smoke (SHS). From lung cancer to emphysema, cigarettes affect the smoker as well as those around them in many harmful ways. Now, however, researchers are beginning to understand that the impact of SHS goes beyond the physical and can result in psychological distress, eventually leading to mental illness.

Researchers looked at over 5,500 non-smoking adults and nearly 2,700 smoking adults who were drawn from a larger health study. The subjects had no history of mental illness. Psychological distress was indicated by a score of 3 or higher on a 12-item health questionnaire as well as admission to a psychiatric hospital during the six years of follow-up. Exposure to cigarette smoke was determined by measuring levels of the biochemical marker cotinine, which is found in the saliva and is an indicator of smoke exposure.

What scientists found was that in about 14.5% of the experimental population, psychological distress was evident. In fact, the odds of this distress in non-smokers with high SHS exposure were 50% greater than when they had low SHS exposure. High cotinine levels were designated as those between 0.70 and 15 micrograms per liter.

The risk of psychological problems was also higher in active smokers. Furthermore, heavy exposure to cigarette smoke, either as an active smoker or through SHS, also appeared to predispose an individual to future psychiatric problems.

The findings, published in the Archives of General Psychiatry, support previous data in animal models that suggests that cigarettes smoke induces negative moods. The data thus adds to the small but growing body of evidence that implicates smoking in mental health issues, including depression. This is particularly relevant in light of the fact that as smoking restrictions in public places have increased the incidence of smoking and smoking exposure in the home, where children and adolescents may be vulnerable.

The study also adds to the overwhelming body of evidence concerning the negative health consequences of smoking. Smoking, without a doubt, is simply bad for you. According to the National Institutes of Health, smoking is responsible for 87% of lung cancer deaths. It also causes other serious health problems, including heart disease, lung disease (including emphysema), stroke, and cataracts. Smoking can also age you prematurely and make you smell bad.

If you smoke, you should quit, and if you don't, never start. For more information, talk to your doctor and visit the website for the Center for Disease Control and Prevention (CDC). For help in quitting, visit the websites for SmokeFree.gov and the American Cancer Society.