A case of carbon monoxide exposure at a Delta, B.C. greenhouse on Saturday affected roughly 40 people. At least 50 people in Canada die of carbon monoxide poisoning every year but there is no national database, Pierre Voisine, a director with the Canadian Association of Fire Chiefs said earlier this year. Here are some incidents that occurred in Canada in recent years:

Nov. 1, 2017: Investigators blamed a lack of boiler maintenance and a deteriorated chimney for a buildup of carbon monoxide gas in a Saskatoon apartment block where a 41-year-old woman was found dead. Fire officials said there was a leak that allowed the gas to escape from the exhaust system and build up in the block's interior.

Oct. 1, 2017: Carbon monoxide poisoning was suspected in the deaths of a man and woman in their 80s whose bodies were found in a west-end Toronto home. Fire officials said high levels of the deadly gas were detected in the residence.

May 3, 2017: Two people were taken to hospital and 26 others were treated on scene after a carbon monoxide leak at a Saskatoon food manufacturing and labelling plant. It was determined a propane-fuelled forklift was the origin of the carbon monoxide.

March 24, 2017: Four people in a home near Ashcroft, B.C. died of carbon monoxide poisoning. RCMP officers who were responding to a request for a check on the home found four bodies inside.

Dec. 11, 2016: A person who died after he was found unresponsive from an apparent heart attack at a Winnipeg business was actually the victim of carbon monoxide. The fire commissioner said a preliminary investigation found a vent cover on the building's chimney had collapsed, preventing it from venting properly. The same business was evacuated the next day when up to 20 people started feeling sick.

May 2014: A member of a work crew employed by a Toronto-based property maintenance business died from exposure to carbon monoxide exposure in a condominium parking garage. Court heard that six workers were using gasoline-powered washers to power-wash the garage when the internal exhaust fans in the garage stopped working. Portable fans were brought in but the workers were still exposed to carbon monoxide gas. Ground Maintenance Cleaning Contractors pleaded guilty to a charge under the Occupational Health and Safety Act and was fined $75,000.

Dec. 1, 2008: Former provincial police officer Laurie Hawkins, her husband Richard and both their children died from carbon monoxide that seeped into in their home in Woodstock, ON, which didn't have a CO detector. The Hawkins Gignac Act, passed by the Ontario legislature in 2013, made carbon monoxide alarms mandatory in all Ontario homes.

News from © The Canadian Press, 2017