"Many people assume that smoking a few cigarettes a day isn't so bad," says study leader Elizabeth Oelsner, MD, a Herbert Irving Assistant Professor of Medicine at Columbia University Vagelos College of Physicians and Surgeons. "But it turns out that the difference in loss of lung function between someone who smokes five cigarettes a day versus two packs a day is relatively small."
The researchers looked specifically at lung function -- the amount of air a person can breathe in and out -- in smokers, ex-smokers, and never-smokers. Lung function declines naturally with age (starting in one's 20s), and it's well-known that smoking accelerates the decline.
Number - People - Study - Oelsner - Colleagues
Because of the large number of people in the study -- more than 25,000 -- Oelsner and her colleagues could see differences in lung function among light smokers (30) that other studies have been unable to detect.
Their analysis found that lung function in light smokers declines at a rate much closer to that of heavy smokers than non-smokers. [Compared to the rate of decline in a never-smoker, set to zero for the analysis, the additional decline for light smokers is 7.65 mL/year and 11.24 mL/year for heavy smokers].
Smoker - Amount - Lung - Function - Year
That means that a light smoker could lose about the same amount of lung function in one year as a heavy smoker might lose in nine months.
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