Researchers studying over 300,000 adults found that even light smoking—just two to five cigarettes a day—dramatically boosts the risk of heart disease and death.
The benefits of quitting are significant, especially in the first decade, but some excess risk remains for decades. Cutting back helps far less than quitting fully.
Low-Intensity Smoking Still Raises Major Cardiovascular Risks
An extensive review of nearly two dozen long-term studies shows that people who smoke only a small number of cigarettes still face a much higher likelihood of heart disease and early death compared to those who have never smoked. This elevated risk persists long after quitting. Michael Blaha of the Johns Hopkins Ciccarone Center for Prevention of Cardiovascular Disease, USA, and his colleagues published these results today (November 18th) in the open-access journal PLOS Medicine.
Scientists have long known that smoking contributes to cardiovascular disease, but the connection between the number of cigarettes someone smokes and their specific level of risk has been less clear, particularly for people who smoke lightly. As smoking habits shift and more individuals consume fewer cigarettes than in the past, gaining a clearer understanding of their long-term heart risks and the benefits of quitting remains essential, even for those who do not come close to a pack a day.
Large Multi-Study Analysis Tracks Smoking’s Long-Term Impact
Blaha’s research team examined health data from more than 300,000 participants across 22 longitudinal studies (which follow people over extended periods) for as long as 19.9 years. During that time, the studies recorded over 125,000 deaths and 54,000 cardiovascular events, including heart attacks, strokes, and heart failure.
Their analysis found that smoking as few as two to five cigarettes per day was linked to a 50 percent higher risk of heart failure and a 60 percent higher risk of death from any cause compared with never smoking. The chance of experiencing a cardiovascular event decreased most noticeably in the first 10 years after quitting and continued to decline the longer someone remained smoke-free. Even so, former smokers still showed higher risks than people who never smoked, sometimes lasting up to 30 years after quitting.
Quitting Early Matters: Cutting Back Isn’t Enough
Because even very light or occasional smoking can significantly raise the chance of heart disease and death, the researchers conclude that quitting altogether at a younger age is the most effective way to protect long-term health. Reducing the number of cigarettes smoked each day does not offer the same level of benefit. The results support long-standing public health recommendations that emphasize early and complete cessation, along with strong programs aimed at preventing people from starting in the first place.
Researchers Highlight the Urgency of Complete Cessation
The authors add, “This is one of the largest studies of cigarette smoking to date using the highest quality data in the cardiovascular epidemiology literature. It is remarkable how harmful smoking is – even low doses of smoking confer large cardiovascular risks.
“As far as behavior change, it is imperative to quit smoking as early in life as possible, as the among of time passed since complete cessation from cigarettes is more important prolonged exposure to a lower quantity of cigarettes each day.”
Reference: “Association between cigarette smoking status, intensity, and cessation duration with long-term incidence of nine cardiovascular and mortality outcomes: The Cross-Cohort Collaboration (CCC)” by Erfan Tasdighi, Zhiqi Yao, Zeina A. Dardari, Kunal K. Jha, Ngozi Osuji, Tanuja Rajan, Ellen Boakye, Kunihiro Matsushita, Eleanor M. Simonsick, Joao A. C. Lima, Donald M. Lloyd-Jones, Debbie L. Cohen, Lawrence J. Appel, Amit Khera, Michael E. Hall, Carlos J. Rodriguez, Suzanne Judd, Shelley A. Cole, Vasan S. Ramachandran, Emelia J. Benjamin, Paulo A. Lotufo, Marcio Sommer Bittencourt, Samar R. El Khoudary, Rebecca C. Thurston, Carol A. Derby, Bruce M. Psaty, Charles B. Eaton, Michael J. LaMonte, Peggy M. Cawthon, Eric S. Orwoll, Aruni Bhatnagar, Andrew P. DeFilippis and Michael J. Blaha, 18 November 2025, PLOS Medicine.
DOI: 10.1371/journal.pmed.1004561
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2 Comments
As a now eighty-one year old adult lifetime non-smoker with previously (late 1981) documented multiple nearly subclinical non-IgE-mediated food and other substance allergies (e.g., tobacco, minimally), born into and raised in a smoking household and breathing second had smoke on-the-job and in public places until those were banned, it’s obvious to me that undiagnosed allergies, probably aggravated with FDA approved added MSG (not mere smoking), are the likely culprit. Sadly, there’s no laboratory testing currently available for my kind of very, very mild allergy reactions, foods, additives or tobacco.
Okay, cigarettes are deadly because you inhale the smoke. What about pipes and cigars that aren’t inhaled? What does a pipeful a day do to you?