Liz Riley started smoking when she was fifteen years old. Like many, she didn't expect it to turn into a 30-year habit, but it did.

"It was very difficult for me to breathe and to exercise and I had a persistent cough that never seemed to go away," she said.

A recent study analyzes just how quickly women can decrease their risk of serious health problems by butting out.

Researchers at Harvard School of Public Health analyzed the results and found that for certain diseases, it doesn't take long.

"There's such a great decline in risk for some diseases that women who are contemplating whether or not to quit really see a benefit quickly with smoking cessation," said Stacey Kenfield of the Harvard School of Public Health.

Researchers studied about 100,000 women from 1980 through 2004. They compared mortality rates for various diseases among current and former smokers to those who had never smoked at all.

They found the risk of dying decreased significantly once women in the study stopped smoking.

"Within the first five years of quitting smoking, we saw a 21 percent reduction in the risk of dying of lung cancer and a fifty percent reduction in the risk of dying of cardiovascular disease specifically coronary heart disease," said Kenfield.

And within twenty years after quitting smoking, some women's risk of dying from cardiovascular disease fell even further, comparable to the level of a non-smoker.

The study appears this week in the Journal of the American Medical Association.

"Once you remove the carcinogens from tobacco smoke from your body your body is able to repair itself," Kenfield said.

Liz Riley says that's what she experienced. She was finally able to stop smoking in 2002

"Immediately I noticed the effects even within the first few days I noticed that I could breathe better."

Liz has peace of mind knowing her decision may likely have prolonged her life.

Researchers hope the findings will motivate others to stop as well.

With a report by CTV British Columbia's Dr. Rhonda Low.