Air pollution has long been linked to health conditions such as stroke, heart disease and lung cancer. According to a new Canadian study, polluted air may also boost the risk of breast cancer.

tracked nearly 90,000 Canadian women over two decades and found that younger women who live in areas that experience high air pollution had a staggering 30 per cent higher risk of developing breast cancer before menopause than others.

Carleton University health sciences researcher Dr. Paul Villeneuve, an author of the study, said it is 鈥渂uilding the evidence that air pollution is indeed linked to the development of cancer.鈥

Emily Piercell was just 27 years old when she found a lump in her breast.

鈥淚 was shocked and scared,鈥 she told 麻豆影视. 鈥淚 don鈥檛 have any cancer, breast cancer in my family. I鈥檓 so young.鈥

The study offers Piercell a possible clue. She grew up in Windsor, Ont., which experiences persistently high levels of fine particle air pollution.

鈥淧ollution is awful for our bodies,鈥 Piercell said. 鈥淪o to see that link, it鈥檚 not surprising to me.鈥

She is now eating right and has taken up half marathons, doing what she can to stay healthy after undergoing a double mastectomy, radiation and chemotherapy.

Researchers suspect that tiny particles in polluted air may promote inflammation or make breasts denser and thus more prone to developing tumours. They believe that the link between pollution and breast cancer is pronounced among women before menopause because their hormones are more active then and may interact more with chemicals in the environment.

Scientists say that the best prevention would be a worldwide reduction in air pollution. Until that happens, Dr. Anthony Miller of the University of Toronto鈥檚 Dalla Lana School of Public Health says there are several things young women can do to lessen their exposure.

鈥淚f you鈥檙e living in an area where there is a great deal of air pollution, you should do your best to remove it from your environment,鈥 Miller, who co-authored the study, told 麻豆影视. 鈥淜eep your windows closed, have good air conditioning with good filters. At the moment, that鈥檚 all we can advise people to do.鈥

Dr. Richard Schabas, who previously served as Ontario鈥檚 Chief Medical Officer of Health and the head of preventive oncology at Cancer Care Ontario, disagrees with the study鈥檚 findings.

鈥淭his (is a) sketchy ecological correlation that doesn鈥檛 even reach statistical significance,鈥 he told 麻豆影视. 鈥淚t could be a trigger for some serious research but it is certainly not a reliable basis for any conclusions at all on its own. Dr. Miller鈥檚 suggestion that people change their lives based on this study is absurd.鈥

According to the , around seven million people die every year from being exposed to fine particles in polluted air.

The study is published in the journal Environmental Epidemiology.

With files from CTV鈥檚 medical affairs specialist Avis Favaro and producer Elizabeth St. Philip