Nav: Home

Ex-smokers, light smokers not exempt from lung damage

October 09, 2019

  • A new Columbia University study shows that just a few cigarettes a day cause long-term lung damage.

  • The impact of smoking on lung function lasts decades, upending an assumption that it only take a few years for the rate of lung function decline to return to normal after smokers quit.
People who smoke fewer than five cigarettes a day cause long-term damage to their lungs, according to a new study led by researchers at Columbia University Vagelos College of Physicians and Surgeons.

"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.

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 (<5 cigarettes>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].

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.

"Smoking a few cigarettes a day is much riskier than a lot of people think," Oelsner says. "Everyone should be strongly encouraged to quit smoking, no matter how many cigarettes per day they are using."

After Quitting, Lungs Don't Fully Recover

The study also tested an assumption, based on a 40-year-old study, that the rate of decline in lung capacity "normalizes" within a few years of quitting smoking.

The new study shows that although lung capacity declines at a much lower rate in ex-smokers (an extra 1.57 mL/year compared with nonsmokers) than current smokers (an extra 9.42 mL/year), the rate doesn't normalize (reach zero) for at least 30 years.

"That's consistent with a lot of biological studies," Oelsner says. "There are anatomic differences in the lung that persist for years after smokers quit and gene activity also remains altered."

Light Smokers and COPD

Smoking's effect on lung function explains why smokers are more likely to develop chronic obstructive pulmonary disease (COPD), which is diagnosed when lung function dips below a certain threshold.

Light smokers may have a greater risk of developing COPD than most researchers have realized, Oelsner says. Most COPD studies have looked only at smokers with heavier habits (>10 pack years).

"We probably need to expand our notions of who is at risk," Oelsner says. "In the future, if we find therapies that reduce the risk of developing COPD, everyone at increased risk should benefit."
-end-
More Information

The study, "Lung function decline in former smokers and low-intensity current smokers: a secondary data analysis of the NHLBI Pooled Cohorts Study," was published online Oct. 9 in The Lancet Respiratory Medicine.

Other authors: Pallavi P. Balte (Columbia University Irving Medical Center), Surya P. Bhatt (University of Alabama at Birmingham), Patricia A. Cassano (Cornell University), David Couper (University of North Carolina, Chapel Hill), Aaron R. Folsom (University of Minnesota), Neal D. Freedman (National Cancer Institute), David R. Jacobs Jr. (University of Minnesota), Ravi Kalhan (Northwestern University, Chicago, IL), Amanda R. Mathew (Rush University Medical Center, Chicago, IL), Richard A. Kronmal (University of Washington, Seattle, WA), Laura R. Loehr (University of North Carolina), Stephanie J. London (National Institute of Environmental Health Sciences), Anne B. Newman (University of Pittsburgh), George T. O'Connor (Boston University), Joseph E. Schwartz (Columbia University Irving Medical Center), Lewis J. Smith (Northwestern University), Wendy B. White (Tougaloo College, Tougaloo, MS), and Sachin Yende (University of Pittsburgh).

The NHLBI Pooled Cohorts Study was funded by the National Institutes of Health, NHLBI, and the US Environmental Protection Agency (R21HL121457, R21HL129924, and K23HL130627).

Columbia authors declare no financial or other conflicts of interest. Columbia University Irving Medical Center provides international leadership in basic, preclinical, and clinical research; medical and health sciences education; and patient care. The medical center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the Vagelos College of Physicians and Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. Columbia University Irving Medical Center is home to the largest medical research enterprise in New York City and State and one of the largest faculty medical practices in the Northeast. For more information, visit cuimc.columbia.edu or columbiadoctors.org.

Columbia University Irving Medical Center

Related Smoking Articles:

Smoking rates falling in adults, but stroke survivors' smoking rates remain steady
While the rate of Americans who smoke tobacco has fallen steadily over the last two decades, the rate of stroke survivors who smoke has not changed significantly.
What is your risk from smoking? Your network knows!
A new study from researchers at Penn's Annenberg School for Communication found that most people, smokers and non-smokers alike, were nowhere near accurate in their answers to questions about smoking's health effects.
Want to quit smoking? Partner up
Kicking the habit works best in pairs. That's the main message of a study presented today at EuroPrevent 2019, a scientific congress of the European Society of Cardiology (ESC).
Smoking and mortality in Asia
In this analysis of data from 20 studies conducted in China, Japan, South Korea, Singapore, Taiwan and India with more than 1 million participants, deaths associated with smoking continued to increase among men in Asia grouped by the years in which they were born.
Predictors of successfully quitting smoking among smokers registered at the quit smoking clinic at a public hospital in northeastern Malaysia
In the current issue of Family Medicine and Community Health, Nur Izzati Mohammad et al. consider how cigarette smoking is one of the risk factors leading to noncommunicable diseases such as cardiovascular and respiratory system diseases and cancer.
Restaurant and bar smoking bans do reduce smoking, especially among the highly educated
Smoking risk drops significantly in college graduates when they live near areas that have completely banned smoking in bars and restaurants, according to a new study in the American Journal of Epidemiology.
How the UK smoking ban increased wellbeing
Married women with children reported the largest increase in well-being following the smoking bans in the UK in 2006 and 2007 but there was no comparable increase for married men with children.
Smoking study personalizes treatment
A simple blood test is allowing Vanderbilt University Medical Center (VUMC) researchers to determine which patients should be prescribed varenicline (Chantix) to stop smoking and which patients could do just as well, and avoid side effects, by using a nicotine patch.
A biophysical smoking gun
While much about Alzheimer's disease remains a mystery, scientists do know that part of the disease's progression involves a normal protein called tau, aggregating to form ropelike inclusions within brain cells that eventually strangle the neurons.
A case where smoking helped
A mutation in the hemoglobin of a young woman in Germany was found to cause her mild anemia.
More Smoking News and Smoking Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Debbie Millman: Designing Our Lives
From prehistoric cave art to today's social media feeds, to design is to be human. This hour, designer Debbie Millman guides us through a world made and remade–and helps us design our own paths.
Now Playing: Science for the People

#574 State of the Heart
This week we focus on heart disease, heart failure, what blood pressure is and why it's bad when it's high. Host Rachelle Saunders talks with physician, clinical researcher, and writer Haider Warraich about his book "State of the Heart: Exploring the History, Science, and Future of Cardiac Disease" and the ails of our hearts.
Now Playing: Radiolab

Insomnia Line
Coronasomnia is a not-so-surprising side-effect of the global pandemic. More and more of us are having trouble falling asleep. We wanted to find a way to get inside that nighttime world, to see why people are awake and what they are thinking about. So what'd Radiolab decide to do?  Open up the phone lines and talk to you. We created an insomnia hotline and on this week's experimental episode, we stayed up all night, taking hundreds of calls, spilling secrets, and at long last, watching the sunrise peek through.   This episode was produced by Lulu Miller with Rachael Cusick, Tracie Hunte, Tobin Low, Sarah Qari, Molly Webster, Pat Walters, Shima Oliaee, and Jonny Moens. Want more Radiolab in your life? Sign up for our newsletter! We share our latest favorites: articles, tv shows, funny Youtube videos, chocolate chip cookie recipes, and more. Support Radiolab by becoming a member today at Radiolab.org/donate.