Former and light smokers subject to adverse health risks
NEW YORK, U.S.: Various studies have examined the oral health implications of tobacco use and smoking cessation. Since it has been proven that smoking accelerates a decline in the function of the lungs, a recent study has assessed lung function in smokers, ex-smokers and those who have never smoked. The findings suggest that even people who smoke fewer than five cigarettes a day cause long-term damage to their lungs.
“Many people assume that smoking a few cigarettes a day isn’t so bad,” said lead author Dr. Elizabeth Oelsner, Herbert Irving Assistant Professor of Medicine at Columbia University Irving Medical Center. “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.”
Owing to the large number of study participants (25,352), Oelsner and her colleagues had the opportunity to observe differences in lung function among light smokers (less than five cigarettes per day) and heavy smokers (more than 30 cigarettes per day). The results showed that lung function in light smokers declines at a rate much closer to that of heavy smokers than to that of nonsmokers. Compared with the rate of decline in those who had never smoked, the additional decline for light smokers was 7.65 mL per year and for heavy smokers was 11.24 mL per year. This suggests that a light smoker could lose almost the same amount of lung function in one year as a heavy smoker does in nine months.
“Smoking a few cigarettes a day is much riskier than a lot of people think,” Oelsner said. “Everyone should be strongly encouraged to quit smoking, no matter how many cigarettes per day they are using.”
The World Health Organization has published a systematic review in which it highlights the immediate and long-term oral health benefits of smoking cessation. In the current study, the researchers tested the hypothesis that the rate of decline in lung capacity normalizes within a few years of smoking cessation. However, although the study showed that lung capacity declines at a much slower rate in ex-smokers than in current smokers, the researchers concluded that ex-smokers would need at least 30 years to normalize their lung function after quitting smoking. “That’s consistent with a lot of biological studies,” Oelsner continued. “There are anatomic differences in the lung that persist for years after smokers quit and gene activity also remains altered.”
The negative effects of smoking on lung function may also explain why smokers are more susceptible to developing chronic obstructive pulmonary disease (COPD). “We probably need to expand our notions of who is at risk,” Oelsner said. “In the future, if we find therapies that reduce the risk of developing COPD, everyone at increased risk should benefit.”
The study, titled “Lung function decline in former smokers and low-intensity current smokers: A secondary data analysis of the NHLBI Pooled Cohorts Study,” was published online on Oct. 9, 2019, in the Lancet Respiratory Medicine, ahead of inclusion in an issue.