Ontario has finally passed a law requiring that all homes with fuel-burning heating systems have at least one carbon monoxide detector. And now one man who lost four members of his family to CO poisoning is trying to get similar laws passed across Canada.

John Gignac's niece Laurie Hawkins died of carbon monoxide poisoning more than five years ago. A blocked chimney allowed the poisonous gas to seep into Hawkins' Woodstock, Ont., home, eventually killing the Ontario Provincial Police officer, her husband Richard, and their two children, 14-year-old Cassandra and 12-year-old Jordan. There were no CO detectors in the home.

Since those tragic deaths, Gignac, a retired firefighter, has fought to make carbon monoxide detectors mandatory in all homes, condos and rental apartments.

Last month, Gignac was pleased to learn that Ontario had passed the Hawkins Gignac Act, which amends Ontario's building code to mandate the installation of CO detectors in all homes -- not just those built after August, 2001, as previous rules stipulated.

Gignac says hearing the news was a bittersweet victory.

"It was with mixed emotions, both sad and happy," Gignac told CTV's Canada AM Thursday. "We're really happy we got the law passed after five years so we can start protecting all people in Ontario, but sad because we can't turn the clocks back five years and put one in my niece's house."

After Hawkins' death, Gignac co-founded the Hawkins-Gignac Foundation for CO Education and says the group's next goal is to get similar laws passed across Canada.

"We look at it as an unfinished painting. We have part of Canada protected, but let's finish the painting and get all Canadians protected," he said.

More than 60 per cent of Canadian homes do not have a carbon monoxide detector, even though the majority of houses in Canada have heating systems that can leak CO.

Carbon monoxide is odourless and colourless and is the same density as air, so if it leaks, it can move freely through a home. Many people miss the signs of CO poisoning because they can come on slowly and often mimic other illnesses, such as flu or food poisoning.

Those symptoms include headache, weakness, nausea and vomiting. More severe poisonings can cause chest pain and confusion.

"The only difference is you won't have a fever. So if you leave the home and you start feeling better, you should start cluing into that carbon monoxide might be present in your home."

Gignac says preventing carbon monoxide poisoning is simple and begins with installing one or several CO detectors in the home. The detectors typically sell for between $30 and $60 and many plug into wall outlets so there's no need to worry about changing batteries.

Gignac recommends installing one on the main floor as well as one outside your sleeping quarters. He also recommends ensuring that furnaces and fireplaces be kept in good working order.

"Everyone should get their heating appliances checked at least once a year by a qualified technician, and make sure the vents are not being blocked by snow and things like that," he says.