Harm Begins With a Few Cigarettes, a Little Smog

Sept. 1 -- MONDAY, Aug. 31 (HealthDay News) -- Even a little bit of poison in the air -- the smoke from a couple of cigarettes, traces of carbon monoxide from auto exhaust -- can do a lot more damage to the heart and lungs than most people think, two new studies show.

One study finds that the biggest increase in the risk of cardiovascular disease comes from smoking three or fewer cigarettes a day. The other finds a marked association between levels of carbon monoxide well below those set by environmental standards and hospital admissions for heart problems among the elderly. Both are published in the Aug. 31 issue of Circulation.

"What motivated our study was not so much cigarette smoking, but the damage done by secondhand smoke," said the author of the first report, C. Arden Pope III, a professor of epidemiology at Brigham Young University in Provo, Utah. "One of the criticisms of the secondhand smoke issue, as well as the air pollution issue, is that it doesn't seem biologically plausible that you can get the kind of effects you see from exposure that is so much smaller than what you get from smoking."

So Pope and his colleagues analyzed data from the American Cancer Society's Prevention Study II, which includes data on more than 1 million adults, as well as other studies of secondhand smoke and air pollution to assess the danger posed by relatively small amounts of smoking.

The idea was to see whether the relationship is a linear one: less smoking exposure, less damage.

The study found that just isn't so. "If you look at cigarette smoking alone, even a few cigarettes a day increase cardiovascular risk by 65 percent," pope said. "If you smoke one or two packs a day, the risk increases by 100 percent. So, most of the increased risk comes from just a few cigarettes a day."

As for secondhand smoke, exposure equivalent to less than one cigarette a day increases the risk of cardiovascular death by 20 percent to 30 percent, the researchers found.