WASHINGON: Smokers who quit by around age 40 can stave off an early death, according to a landmark study that fills key gaps in knowledge of smoking-related health ills.

While smokers who never stop lose about a decade of life expectancy, those who quit between ages 35 and 44 gained back nine of those years, the study found.

Moreover, the benefits of dropping the habit extend deep into middle age. Smokers who quit between 45 and 54 gained back six otherwise lost years, and those who quit between 55 and 64 gained four years.

Quitting young, before age 35, erased the entire decade of lost life expectancy.

The message: it’s never too late to quit, even for heavy smokers with decades of puffing behind them.

But younger smokers should not be lulled into thinking they can smoke until 40 and then stop without consequences, said Prabhat Jha, an epidemiologist at the Center for Global Health Research in Toronto.

The risks of lung cancer and other respiratory diseases linger for years after stubbing the last butt.

Most of the gains in life expectancy come because the twin risks of heart disease and stroke quickly drop after smoking ends.

Both diseases occur as the by-products of tobacco smoke trigger clotting in the arteries, a process that can rapidly reverse.

By arrangement with the Washington Post/Bloomberg News Service