If you have ever been in a smoky bar or stood next to someone smoking a cigarette, you probably know what it's like to experience secondhand smoking: accidental inhalation, coughing, and the smell left on your clothes and hair. While occasional exposure to others' tobacco smoke is not as harmful as being a smoker yourself, continued exposure to secondhand smoke can cause serious health problems.
Causes
Secondhand smoke is the term for any smoke---usually from cigarettes---that you inhale when it is produced by someone else. If you stand near someone who is smoking, you will likely inhale some of the smoke the person exhales or the smoke the cigarette is producing. Smoke inhaled from wildfires or controlled burning of grass seed fields, for example, is also considered a form of secondhand smoke. Secondhand smoke from these sources can be dangerous for asthmatics and others. However, cigarette smoke can be the most harmful form of secondhand smoke, because the exposure is often long term, and it contains more than 4,000 chemicals, at least 250 of which are toxic or carcinogenic.
Studies
Over the past few decades, much research has been conducted on secondhand smoking. People whose spouses smoke and children whose parents smoke are at high risk of lung cancer and asthma, respectively. Children exposed to secondhand smoke are at an increased risk for many health problems, including sudden infant death syndrome, acute respiratory infections, ear problems, and more severe asthma, studies have shown. Environmental tobacco smoke has been shown to pollute the air at a higher rate than an idling, low-emission diesel engine. Breathing smoke reduces blood flow and constricts arteries, raising the risk of a heart attack, even in healthy nonsmokers. The surgeon general has determined that there's no level of exposure to secondhand smoke that is risk-free.
Links to Cancer
More than 60 of the chemical compounds found in cigarette smoke are carcinogenic, or known to cause cancer. According to the American Cancer Association, secondhand smoke is linked to about 3,400 lung cancer deaths in non-smoking adults each year. New research suggests a possible link between secondhand smoke exposure and breast cancer, especially in younger women, but these claims have yet to be proven definitively.
Controversy
In the past, some studies claimed that the link between passive smoking and health problems was not as strong as other research indicated. However, many of those studies have turned out to be funded in part by the tobacco industry, which has invested a lot of money into denying its products are harmful. In 1998, the World Health Organization study was accused of suppressing a report that failed to prove a link between secondhand smoke and lung cancer, but the organization responded in a press release that "passive smoking causes lung cancer in non-smokers."
Avoid the Smoke
One frustrating aspect of secondhand smoke is that it can be hard to control. Though smoking bans in public places are becoming more common, smoking is still allowed in many bars and restaurants, outdoor areas and often the cars and private homes of smokers. Though the exact effects of secondhand smoke may be unclear, it is best to limit your exposure, especially if you have other breathing problems or a compromised immune system. Stay away from enclosed areas where smoking is permitted.
