More smokers would kick the habit with a little help and easier access to nicotine patches, US researchers said on Friday.

Smoking, the biggest preventable cause of death in the world, kills 5 million people a year. By 2025, the number of deaths could rise to 10 million annually.

But researchers at the New York City Department of Health and Mental Hygiene who gave a free 6-week course of nicotine patches to the first 35,000 caller to a smokers’ quitline said it helped many of them stop.

Of the 1,300 smokers who were randomly selected for a six-month follow-up after receiving the patches, 33 percent of them had stopped smoking.

“At a modest cost, we were able to reach a large number of smokers with medication and brief counselling, which improved the success rate of quit attempts,” Dr. Thomas Frieden said in a report in The Lancet medical journal.

He and his colleagues estimate that at least 6,000 smokers quit, at a cost of about $464 each, because of the free programme.

“Although New York City implemented the programme at a time when new smoke-free workplace legislation and increased taxation on cigarettes focused public attention on cessation, these findings suggest the potential for similar intervention to encourage large numbers of smokers to attempt to quit smoking,” Frieden added.

Research has shown that cigarette smokers die on average 10 years earlier than non-smokers. But quitting the habit, even at 50 years old, can halve the risk.

Smoking is the leading cause of lung cancer. It is also a risk factor for Heart disease, Stroke, other types of cancer and age-related macular degeneration, the main cause of adult blindness.