New Delhi, Sept. 22: Light smokers might not escape the life-threatening effects of smoking. People who light up just one to four cigarettes a day have triple the risk of dying from heart disease or lung cancer than non-smokers, a new study has said.

A study by Norwegian scientists that investigated the health and causes of deaths of more than 42,000 people over 25 years has dispelled the popular notion that a few cigarettes each day won’t harm health.

The study has shown that light smokers ? men and women ? had significantly higher death rates than people who had never smoked. The death rates corresponded to the number of cigarettes smoked each day.

“Policy makers and health educators should emphasise more strongly that light smokers are also endangering their health,” the public health researchers from two Norwegian institutions have said in the latest issue of the journal Tobacco Control.

Men who were light smokers were three times as likely to die from lung cancer as men who had never smoked, while light women smokers were five times as likely to die from lung cancer as non-smoking women, the study indicated.

Few studies had so far explored the health effects of smoking less than five cigarettes per day. Health researchers have been concerned that there might be a widespread belief among the general public that some threshold value of daily cigarette consumption must be exceeded before serious health consequences occur.

The Norwegian study indicates that even less than five increased risk of dying.

The study covered 23,500 men and 19,200 women who had been first screened for risk of cardiovascular diseases and questioned about their smoking habits in the mid-1970s.

Two years ago, the researchers checked if they were alive ? and the cause of death of those who had died ? and tried to connect this with smoking histories.

The men and women studied had varying smoking habits. Some had never smoked, while in smokers daily cigarette consumption varied from one to more than 25 cigarettes a day. The scientists concede that people might have changed their smoking habits over the years.

The findings “confirm and strengthen” observations from at least three earlier studies on the risks of heart attacks in people with varying smoking habits. A study conducted between 1976 and 1988 had shown that the risk of heart attacks rose with increasing cigarette consumption.