Updated

While much has been done to address the dangers of indoor second-hand smoke, efforts to minimize the dangers of outdoor secondhand smoke are only just beginning.

Although outdoor smoke dissipates more quickly than indoor smoke, it still affects the air quality of nonsmokers sitting or standing a few feet downwind from a smoker, Neil Klepeis, a Stanford University assistant professor (consulting) of civil and environmental engineering, told Foxnews.com this week.

“Being within a few feet of a smoker or a (lit) cigarette has the potential to expose a person to air pollution levels that are similar to indoor secondhand smoke,” said Klepeis, who co-authored a study on outdoor secondhand smoke that was released this past summer.

The Great American Smokeout is Thursday. Smoking kills an estimated 438,000 Americans and costs the nation nearly $100 billion in medical expenses each year, according to the CDC. Tens of thousands of Americans die each year from secondhand smoke, according to a 2006 report from the Surgeon General. Currently, 21 percent of Americans smoke.

In response to concerns about outdoor secondhand smoke, several communities and states have begun to enact bans similar to those enacted on indoor smoking.

For his study, Klepeis and other researchers measured pollution from tobacco smoke at parks, open-air cafes, sidewalks and outdoor pubs.

The study found that nonsmokers sitting a few feet away from a smoker in an outdoor setting were exposed, on average, to 200 to 300 micrograms per meter cubed of pollutants called particulate matter2.5, and 500 to 1,000 micrograms for brief periods of time.

The U.S. Environmental Protection Agency’s air standard calls for no more than 35 micrograms per cubic meter of particulate matter2.5, which has been linked to serious health problems, including asthma attacks, chronic bronchitis, irregular heartbeat, nonfatal heart attacks and even premature death in people with heart or lung disease.

Klepeis said smokers who congregate outside of bars, restaurants and office buildings in groups are even more harmful to nonsmokers standing within a few feet of them.

“If you’re standing in line outside a club waiting to get in and you have a group of people smoking outside, you’d have to multiply our results by the number of smokers that are present,” he said. “For example, we found that, on the high side, nonsmokers can be exposed to 1,000 micrograms of particulate matter, but if you have 10 people smoking at the same time, you have to multiply that number by 10.”

Klepeis said the study indicates that nonsmokers should avoid congregating in outdoor areas where smoking is taking place. It also makes a valid argument for banning outdoor smoking at restaurants, bars, parks, bus and transportation terminals, as well as near the doorways of office buildings, apartment complexes and hospitals.

More than 700 state and local governments have passed laws restricting outdoor smoking, according to the American Nonsmokers' Rights Foundation. California has some of the strictest laws. The state has banned smoking within 20 feet of entrances to any public building.

Additionally, the city of Santa Monica banned smoking at parks, beaches, ATM machines, theater lines, and open-air restaurants.

Belmont, Calif. banned smoking in outdoor places and inside condos, apartments and other kinds of multi-unit housing in September.

Elsewhere in the U.S., Ashland, Ky. prohibits smoking in outdoor arenas, venues and outdoor patio areas of restaurants and bars. In Bloomington, Minn., smoking is prohibited within 25 feet of entrances and in 50 percent of outdoor eating areas of restaurants.

Internationally, other countries are following suit. Selected wards in Tokyo, Japan prohibit smoking on the streets. In response, free smoking cafes have been provided by the country’s largest tobacco company, Japan Tobacco.

In Canada, British Columbia bans smoking near public doors, at bus stations, and near or on school grounds. A province-wide ban on smoking in public places starts in 2008. And Edmonton, Albertaand Nova Scotia ban all outdoor patio smoking at bars, restaurants and casinos.

For more on outdoor smoking bans, click here

Klepeis and his team are now conducting studies on the effects of multiple smokers congregating in outdoor areas, as well as researching the indoor/outdoor transfer of tobacco smoke and the effects of second-hand smoke in an apartment setting.