Smoking and Life Expectancy: Do the Math!

A recent study indicates that smoking significantly reduces life expectancy. However, it emphasizes that quitting this habit at any age can greatly improve life expectancy.
“Smoking kills.” Despite this clear warning on cigarette packs, many people continue to smoke. According to the World Health Organization’s (WHO) report on the global tobacco epidemic published in 2021, smoking kills more than half of long-term smokers and is responsible for approximately 7 million deaths annually. However, a June 2021 study in The Lancet shows that smoking rates have significantly decreased since 1990 among individuals aged 15 and older, with drops of 27.5% for men and 37.7% for women. Despite this progress, due to population growth, the total number of smokers has risen from 0.99 billion in 1990 to 1.14 billion in 2019. Furthermore, according to the same statistics, the total number of tobacco-related deaths continues to rise in many low- and middle-income countries, which are home to the majority of the world's smokers.

Quitting Smoking



Over the past decades, numerous scientific studies have examined the detrimental effects of smoking. However, few have thoroughly assessed its impact on life expectancy and the potential benefits of quitting smoking. A study published in June 2024 in the American Journal of Preventive Medicine (AJPM) provides new insights and findings on these critical questions. This study first analyzed mortality rates based on age and smoking status (non-smokers, current smokers and former smokers), then developed survival tables for these groups, comparing life expectancies of individuals who quit smoking between ages 35 and 75. Finally, it assessed the years of life lost due to smoking and the potential life expectancy benefits of quitting this habit at different life stages.

Life Expectancy


The findings reveal a substantial decrease in life expectancy among smokers. Researchers estimated that people who started smoking at age 35 and continued throughout their lives would lose an average of 9.1 years compared to non-smokers. For those who started smoking at ages 45, 55, 65, and 75, the average decreases were 8.3, 7.3, 5.9, and 4.4 years respectively. This translates to a decrease in life expectancy by 27.7%, 33%, 38.9% and 48.2% compared to those who have never smoked. Meanwhile, adults who quit smoking at these ages (from 35 to 75) would have a life expectancy lower than non-smokers of the same age by 1.2, 2.7, 3.9, 4.2, and 3.7 years, respectively. In essence, people who quit smoking could potentially extend their lives by one to eight years. Finally, according to these results, the likelihood of extending one's life by at least one year by quitting smoking at ages 65 and 75 is 23.4% and 14.2%, respectively.
This study thus confirms the importance of quitting smoking as an effective way for smokers to increase their life expectancy. According to the study’s authors, “The benefits of quitting is not limited to young and middle-aged adults’ smokers; this study also indicates that it applies to older people as well. These findings provide valuable scientific evidence for clinicians aiming to encourage their smoking patients to quit.”
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