More than 40 people exposed to carbon monoxide in a greenhouse in Delta, B.C., on Saturday were taken to hospital.

B.C. Emergency Health Services said 13 ambulances responded to the incident. Thirty-two people were in stable condition and 10 in "serious to critical" condition.

The incident happened at Windset Farms in the Ladner area, according to the Delta Fire Department.

Deputy Chief Guy McKintuck said it appears combustion-powered pressure washers being used in an insufficiently ventilated area.

 "[Our crews] weren't sure what it was at first, but through their investigation, they quickly realized that it was a carbon monoxide incident and they acted accordingly," McKintuck said.

WorkSafeBC confirmed it is investigating.

Carbon monoxide — sometimes referred to as CO — is a colourless, odourless gas released as a byproduct of incomplete combustion, toxic to humans and most other animals. CO exposure can cause headaches, nausea, vomiting, dizziness and disorientation, and eventually death.