In recent years, several states and municipalities have made it illegal to smoke in any workplace, including bars and restaurants. A researcher with a long interest in second-hand smoke looked at air quality before and after the Delaware smoking ban.

What the researcher wanted to know: How did the smoking ban affect pollutant levels inside several businesses in Wilmington, Delaware?

What he did: The researcher went to eight places where people smoke - one casino, one pool hall, one stand-up bar, and five bar/restaurants. He went to each place twice, on a Friday evening before the ban and a second Friday after the ban, and dragged along a piece of luggage that concealed air quality monitors.

What he found: The smoking bans worked on reducing secondhand smoke. Levels of chemicals from cigarette smoke were much lower in the indoor air after the ban. After the ban, levels of respirable particles and carcinogenic particulate polycyclic aromatic hydrocarbons were almost as low inside as outside. The researcher says the levels of particulate pollution before the ban were higher than on Interstate 95 in Delaware.

What the study means to you: Well, it does seem kind of obvious that a smoking ban would decrease the levels of chemicals that come from smoke.

Caveats: Each venue was measured only once before and once after the ban, so the researcher couldn't average levels over several days.

Find out more: The Delaware Tobacco Prevention Coalition asked the researcher to do the study.

Read the article: Repace, J. "Respirable Particles and Carcinogens in the Air of Delaware Hospitality Venues Before and After a Smoking Ban." Journal of Occupational and Environmental Medicine. September 2004, Vol. 46, No. 9, pp. 887–905.

Abstract online: www.joem.org