What are the risks of secondhand or environmental smoke?

In 1991, the Environmental Protection Agency (EPA) reported that 20% of lung cancers diagnosed among nonsmokers were due to exposure to environmental tobacco smoke, making the risk of developing a smoking-related disease 1:1000, higher than all chemically related environments regulated by the EPA. Today, secondhand smoke is thought to contribute to about 3400 lung cancer deaths and 23,000 to 70,000 cardiovascular deaths in U.S. nonsmokers annually. It is especially harmful to young children and is thought to be responsible for between 150,000 and 300,000 respiratory tract infections in children under 18 months of age, resulting in between 7500 and 15,000 hospitalizations annually. It is thought to be one of the causes of sudden infant death syndrome (SIDS). The most recent Surgeon General's Report concluded that even brief exposures to secondhand smoke can cause blood platelets[1] to become stickier, damage the lining of blood vessels, decrease coronary artery blood flow, and increase the risk of an acute heart attack.

Following this report, there has been progress in improving the number of workplaces that are smoke-free. National trends for smoke-free environments have continued to improve from 46.3% in the years 1992-1993 to 70.9% in 2001-2002.

Does my risk for a specific illness related to smoking change after I quit smoking?

If you stop smoking, the benefits to your health and longevity are great. Becoming smoke free has health benefits no matter how long you have smoked. The body starts repairing itself almost immediately after smoking cessation, but some organs may not be able to recover completely, depending upon the length of time you have smoked.

In general, the excess risk among former smokers drops substantially in the first two to three years. Thereafter, the rate of decline decreases so that it takes up to 10 years for former smokers to reach the same risk level as that of persons who have never smoked. The slow decline in all morbidity and mortality due to coronary heart disease is related to reversal of some atherogenic effects of smoking. The risk of myocardial infarction diminishes by almost one-third after the first year of smoking cessation and reaches the level of persons who have never smoked by the third or fourth year. The rapid decline in heart attack (myocardial infarction) risk is thought to be due to a rapid reversal of hypercoagulability induced by smoking. The risk of sudden death due to all cardiovascular events takes longer to be reduced to nonsmokers' levels, anywhere from 5 to 15 years.

What are my chances of recovery from smoking-related diseases such as cardiac disease, lung cancer, chronic pulmonary disease (including emphysema), and stroke?

It is important to remember that all of these diseases can occur independently of whether or not someone smokes. These diseases are age related, and diet, activity, and exposure to other environmental toxins can contribute to their development. Never having smoked is no guarantee one will avoid these diseases. Therefore, quitting smoking is no guarantee of avoiding them either. Smoking merely increases the risk and accelerates the course of the disease once someone has developed it. With that in mind, quitting smoking certainly lowers one's risk and slows down the progress of disease. So the real issue is whether or not quitting lowers the risk back to nonsmokers' levels.

Cardiovascular Diseases: These are diseases of the heart or blood vessels (arteries and veins). Heart disease kills more Americans than cancer. A six-year follow-up study of people older than 55 years, who were smokers, found that the death rate was significantly higher among smokers who continued to smoke than among those who had quit. It takes anywhere between 5 and 15 years after one quits smoking to lower one's risk back to that of a nonsmoker.

Lung Cancer: Smoking cessation reduces lung cancer risk by 30% to 50% 10 years after quitting. The risk that you will develop lung cancer decreases with further years of abstinence. The risk of lung cancer is always a possibility though when compared to someone who has never smoked. For example, approximately 50% of all lung cancers are diagnosed in ex- smokers.

Chronic Obstructive Pulmonary Disease, Including Emphysema: Chronic obstructive pulmonary disease (COPD) is a term for a group of lung conditions that restrict airflow, making breathing difficult. The conditions include:

Emphysema: breathlessness caused by damage to the air sacs (alveoli) causing them to become less elastic.

Chronic bronchitis: coughing with a lot of mucus that continues for at least three months.

Smoking is the most common cause of COPD and is responsible for 80% of cases. Approximately 90% of 1 pack/day smokers have some emphysema on postmortem examination, while more than 90% of nonsmokers have little or no emphysema on postmortem examination. COPD typically occurs after the age of 40, when lung function starts to decline anyway.

In smokers, the rate of decline in lung function can be three times the rate of nonsmokers. As the condition progresses, severe breathing problems can require hospital care. The final stage is death from slow suffocation, which is a progressive loss of the ability to oxygenate the body. The rate of decline may or may not revert to that of a nonsmoker. If lung damage has occurred due to smoking, the damage may never be completely repaired. This means that the lung function will still be diminished compared to someone who has never smoked.

Stroke: A stroke occurs when there is a rapid loss of brain function because of a disturbance in the blood vessels that carry blood to the brain. Strokes can be thought of as brain attacks in the same manner that people suffer heart attacks. The mechanism is the same, except the atherosclerotic buildup is located in the major arteries supplying blood to the brain as opposed to the heart. As a result, the risk of stroke follows the same general pattern as the risk of coronary artery disease.

While not inhaling reduces the direct exposure of tar and nicotine to the lungs, it does not eliminate exposure.

Within a few years after quitting smoking, the risk of having a stroke decreases. The risk of stroke is highest in smokers under age 55 and decreases with age. There is also a dose-response effect between the number of cigarettes smoked and risk of stroke. Researchers have found strong correlations between smoking and thrombotic stroke (slow decrease in blood supply), embolic stroke (sudden release of a blood clot), and subarachnoid hemorrhage (blood leaking from the vessels and pooling in the brain). The relative risk of subarachnoid hemorrhage was significantly higher than that of thrombotic stroke.

If I don't inhale will I have less of a chance of getting a disease, such as lung cancer?

It is important to remember that there both direct and indirect risks from smoking, whether or not one inhales. You are still exposing your body to tar and nicotine. While not inhaling reduces the direct exposure of tar and nicotine to the lungs, it does not eliminate exposure. Smokers who do not inhale are still breathing secondhand smoke and continue to be at risk for lung cancer. Additionally, the carcinogenic effects of tar and nicotine are still absorbed by the body, and therefore the risk of a variety of cancers, such as bladder cancer and pancreatic cancer, remains unchanged. While the direct toxicity of tar and nicotine is reduced to the lungs, it continues to have direct toxic effects to the mouth, gums, teeth, tongue, nasal linings, and esophagus. Pipe and cigar smokers, who often do not inhale, are at an increased risk for lip, mouth, tongue, and some other cancers. Even limited smoking, such as one or two cigarettes per day, or inhaling three to five grams of tobacco per day (environmental smoke) puts your health at risk.

  • [1] (Also known as thrombocytes.) A type of blood cell involved in the cellular mechanisms of the formation of blood clots. Low levels or dysfunction predisposes for bleeding, while high levels, although usually asymptomatic, may increase the risk of the development of a thrombus.
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