Scientific Evidence Shows Secondhand Smoke Damages Lungs

< Nov. 28, 2007 -- The first study to produce evidence linking secondhand smoke to lung damage has just been released. The news comes during Lung Cancer Awareness Month, which is observed each year during the month of November.

Secondhand smoke is smoke that is exhaled by smokers and smoke emitted from the burning end of a lit cigarette, cigar, or pipe.

Using a special type of magnetic resonance imaging (MRI), researchers at the University of Virginia School of Medicine and The Children's Hospital of Philadelphia have identified structural damage to the lungs caused by secondhand smoke.

"It's long been hypothesized that prolonged exposure to secondhand smoke may cause physical damage to the lungs, but previous methods of analyzing lung changes were not sensitive enough to detect it," says Chengbo Wang, Ph.D., magnetic resonance physicist at The Children's Hospital of Philadelphia.

The findings were presented earlier this week at the annual meeting of the Radiological Society of North America (RSNA).

MRI Uses Special Helium

Dr. Wang's team used long-time-scale, global helium-3 diffusion magnetic resonance imaging (MRI) to study the lungs of 43 volunteers. This included seven current and former smokers and 36 people who had never smoked, 18 of whom had a high level of exposure to secondhand smoke.

Helium-3, also known as hyperpolarized helium, is an inhaled magnetic resonance (MR) contrast agent used to study the function and structure of the lung.

Helium-3 diffusion MRI is different from a conventional MRI because the patient inhales a specially prepared helium gas before imaging. The scanner is then adjusted to take images showing this helium gas in the tissue.

MR measures how far the helium atoms move, or diffuse, inside the lungs during a specific time period, which was 1.5 seconds in this study. With this method, radiologists and physicists can detect changes deep in the small airways and sacs in the lungs.

These passageways can break down, become enlarged, and develop holes after prolonged exposure to cigarette smoke. Helium-3 diffusion MRI identifies this damage by measuring the increased distance the helium atoms move.

“With this technique, we are able to assess lung structure on a microscopic level,” Dr. Wang says.

Early Signs of Lung Damage Seen

Eighteen of the 36 study participants had a high level of secondhand smoke exposure.

The results showed that 57 percent of smokers and 33 percent of the nonsmokers with high exposure to secondhand smoke appeared to have early signs of lung damage. In addition, 14 percent of smokers and 67 percent of nonsmokers with high exposure to secondhand smoke showed evidence of developing respiratory problems such as asthma or chronic bronchitis.

"These findings suggest that breathing secondhand smoke can injure your lungs," Dr. Wang says. "Since legislation to limit public exposure to secondhand smoke is still being considered in many states, we hope that our work can be used to add momentum to the drive to pass such legislation."

Why Worry About Secondhand Smoke?

What are the risks of secondhand smoke? The American Heart Association estimates that approximately 38,000 people die each year from heart and blood vessel disease caused by secondhand smoke.

Both direct and indirect smoking exposure poses significant health hazards to pregnant women, infants, and young children. Children and infants exposed to tobacco smoke are more likely to experience ear infections and asthma, and are at a higher risk for sudden infant death syndrome (SIDS) than children and infants without the same exposure.

The following common symptoms may be associated with exposure to secondhand smoke. However, each individual may experience symptoms differently. Symptoms may include:

• irritation of the eyes, nose, and throat

• coughing

• excessive phlegm (mucus in the airways)

• chest discomfort from lung irritation

• chest pain, which may indicate heart disease

The symptoms of secondhand smoke may resemble other medical conditions and problems.

Always consult your physician for more information.

Avoiding Secondhand Smoke

According to the American Cancer Society, there are primarily three places where you should be concerned about exposure to secondhand smoke:

The Workplace

Your workplace may be a major source of secondhand smoke exposure.

Secondhand smoke is classified as a potential cancer-causing agent by the Occupational Safety and Health Administration (OSHA), the federal agency that maintains responsibility for health and safety regulations in the workplace.

The National Institute for Occupational Safety and Health (NIOSH), another federal agency, also cautions that secondhand smoke should be considered a potential occupational carcinogen, or a substance that is known to cause cancer.

Because there are no known safe levels of secondhand smoke, they recommend that exposure to secondhand smoke be kept to the lowest possible levels.

Secondhand smoke exposure in the workplace has also been associated with an increased risk in heart disease and lung cancer among adult non-smokers.

The Surgeon General has determined that smoke-free workplace policies are the only effective way to eliminate secondhand smoke exposure in the workplace.

If people smoke inside the building, measures such as separating smokers from non-smokers, cleaning the air, and ventilating the building cannot prevent exposure.

In addition to protecting non-smokers, workplace smoking restrictions may also encourage smokers who want to quit or cut down on their use of tobacco products.

Public Places

Everyone can be exposed to secondhand smoke in public places, while eating in restaurants, shopping in malls, taking public transportation, attending schools, and in daycare centers.

Although some businesses are reluctant to ban smoking, it remains to be seen if a non-smoking policy actually hurts business.

Your Home

Maintaining a smoke-free home may be one of the most important things you can do for the health of your family.

Any family member can develop health problems related to secondhand smoke.

Children are especially sensitive to secondhand smoke. In the United States, 21 million children (35 percent) live in homes where residents or visitors smoke in the home on a regular basis.

About 50 to 75 percent of children in the US have some level of cotinine, the breakdown product of nicotine, in their blood.

We spend more time at home than anywhere else. A smoke-free home protects you, your family, your guests, and even your pets.

Always consult your physician for more information.