U.S. study performed at the University of Minnesota found that heavy smokers who cut back their daily cigarettes’ use still experienced greater exposure to toxins per cigarette in comparison to light smokers.

Study participants were divided into two groups and were given as few as five cigarettes a day. The results showed that ex heavy smokers who reduced the number of cigarettes per day still received two to three times the amount of total toxins per cigarette compared to light smokers.

One of the reasons lies in the so called "compensatory smoking", a process in which an ex heavy smokers takes more frequent puffs or inhales deeper and longer on each cigarette to compensate for smoking less.

While cutting back does decrease toxin exposures in regular heavy smokers, these toxin levels are much higher than those in light smokers.