Among the most devastating consequences of smoking are cardiovascular diseases (CVD), which include heart attacks, strokes, and heart failure. Smoking contributes significantly to premature death, reduced life expectancy, and long-term health complications.

A new study published in ‘PLOS Medicine’ highlights just how dangerous even low levels of cigarette consumption can be. Interestingly, people who smoke only a couple of cigarettes a day still face surprisingly high risks of heart problems and early death. Specifically, low-intensity smoking, defined as two to five cigarettes per day, was associated with a 50 per cent higher risk of cardiovascular disease and a 60 pc higher risk of all-cause mortality compared to individuals who have never smoked. These findings underscore that even minimal use can have serious long-term health consequences.

What the new study says 

The study was conducted by a research team led by Michael Blaha from the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease. The researchers analysed data from 22 long-term population studies conducted across multiple countries. Together, these studies followed more than 3.2 lakh adults for nearly 20 years. This large dataset allowed scientists to examine the links between smoking burden, daily cigarette consumption, time since quitting and long-term cardiovascular and mortality outcomes.

During the follow-up period, more than 1.25 lakh deaths and over 54,000 cardiovascular events were recorded, including heart attacks, strokes, heart failure and abnormal heart rhythms such as atrial fibrillation. Participants were grouped based on how many cigarettes they smoked per day and whether they had quit. Earlier research had already shown that heavy smoking dramatically increases the risk of heart disease and early death. However, the relationship between low-intensity smoking and long-term cardiovascular outcomes had remained less well defined.

One of the most striking findings was just how dangerous low-intensity smoking actually is. Individuals who smoked only two to five cigarettes per day had about 50 pc higher risk of cardiovascular disease and about 60 pc higher risk of death from any cause compared with never-smokers.

People who smoked 11 to 15 cigarettes per day faced even greater danger, with almost 1.9 times higher risk of cardiovascular disease and more than 2.3 times higher risk of dying from any cause. The researchers observed that risk rises sharply at the earliest levels of smoking exposure.

The first 20 cigarettes per day and the first 20 pack-years of smoking account for a large share of total cardiovascular damage. This means the heart and blood vessels suffer early and significant injury even when cigarette consumption is relatively low. The toxic chemicals in cigarette smoke cause inflammation, promote plaque buildup, reduce oxygen supply and disturb heart rhythm.

The study also found that current smokers had roughly two times higher risk of cardiovascular disease and more than two times higher risk of death from all causes compared with never-smokers. Women smokers showed slightly higher relative risks for certain heart conditions than men.

However, the researchers noted that “smoking status was determined based on self-reported data from individual cohort surveys. The stigma attached to smoking could lead to underreporting of current smoking status, particularly among women, affecting the accuracy of the data.”

Why cutting down is not enough

A common belief among smokers is that reducing the number of cigarettes they smoke daily will significantly lower their health risks. This study directly challenges that assumption. The data clearly show that cutting down without quitting entirely does not remove the cardiovascular danger. Even those who reduced intake to only a few cigarettes daily remained at significantly elevated risk of heart disease and early death.

According to the researchers, it is not just how much one smokes that matters, but how long the body continues to be exposed to tobacco toxins. Each cigarette delivers nicotine, carbon monoxide and thousands of harmful chemicals into the bloodstream. These substances repeatedly damage blood vessels, and when smoking continues over months or years, even at low levels, the injury steadily accumulates.

“As far as behaviour change, it is imperative to quit smoking as early in life as possible, as the amount of time since complete cessation from cigarettes is more important than prolonged exposure to a lower quantity of cigarettes each day,” the authors add.

The only real protection is quitting completely

While the harm caused by smoking is severe, the study also offers hope for those who quit. The greatest improvement in cardiovascular risk occurs within the first ten years after cessation. Risk continues to decline over the next two decades. About 20 years after quitting, former smokers experience more than 80 per cent reduction in excess cardiovascular and mortality risk compared with current smokers.

However, even after two to three decades, former smokers still carry slightly higher risks than people who never smoked, particularly for heart attacks and cardiovascular death. Quitting at a younger age leads to faster and more complete recovery than quitting later in life.

The findings also show that smokers enrolled in more recent decades face higher risks than those enrolled earlier, possibly due to earlier initiation, longer exposure and changes in cigarette composition. This strengthens the need for aggressive tobacco control policies and strong prevention efforts.

What it means for us: expert insights 

Dr (Prof) Tarun Kumar, Associate Director at Medanta Moolchand Heart Center, says the findings of the new study are highly relevant for India and, in fact, may be even more alarming in the Indian context. According to him, the risks associated with smoking one or two cigarettes a day could be higher in India than in many Western countries because of the additional burden of air pollution.

“Yes, I completely agree that these trends apply to India. In fact, the impact here may be more severe. We are already living in a highly polluted environment. Breathing Delhi air itself can be equivalent to smoking 15 to 20 cigarettes a day, depending on the AQI,” he explains. “Now if a person smokes even one or two cigarettes on top of this, the total toxic exposure becomes much higher than in cleaner environments.”

Dr Kumar stresses that smoking is an “all-or-none” risk factor. “If you are smoking, the risk is there from the very beginning. The risk only increases with the number of cigarettes. There is no such thing as safe smoking,” he says. He also clarifies that the body does not recover immediately after quitting. “It is not that you stop smoking today, and from tomorrow your risk becomes zero. The damage done to the lungs, arteries and heart takes a long time to reverse.”

He strongly supports the study’s emphasis on early cessation, noting that the duration of smoking plays a critical role in long-term harm. “If someone has been smoking for 20 years, changes are already well established in the lungs, blood vessels and heart. But if someone has smoked only for two years, the damage is still limited. That is why early quitters benefit much more than those who quit late,” he says.

Dr Kumar also confirms that light smokers and recent quitters in India continue to show significant heart risk, especially among younger patients. “One of the most common risk factors we see in young patients coming with heart attacks is smoking. The second major factor is uncontrolled diabetes. These two together are driving early heart disease in our population,” he says.

According to him, the misconception that only heavy smokers suffer heart attacks is dangerous. “Even so-called light smokers are coming with serious cardiac events. This is exactly why studies like these are important. They force people to understand that even minimal smoking can have life-threatening consequences.”

Speaking about quitting strategies, Dr Kumar underlines that willpower is the foundation of successful cessation. “The first and most important thing is a strong will. If a person keeps making excuses or believes that smoking is not harmful, it becomes very difficult to quit,” he explains.

He adds that counseling plays a key supportive role. “Behavioural counselling helps the smoker understand triggers and build long-term discipline. In addition, nicotine substitutes like chewing gums and other medical therapies can be used to control cravings. But everything starts with intent.”