Second-hand cannabis smoke: Researchers investigate involuntary THC exposure in homes

University of Toronto researchers are investigating exposure to second-hand - and even third-hand - marijuana smoke in homes, including the THC that can collect on floors and surfaces. The researchers, in Faculty of Applied Science & Engineering, have  published a new study  that models how THC - the main psychoactive ingredient in cannabis - behaves and transforms once it is released in an indoor environment. The model enables researchers to explore mitigation strategies that could reduce involuntary exposure levels.   "We began our research on tetrahydrocannabinol (THC), which is the psychoactive part of cannabis that causes intoxication, because when we looked at secondand third-hand smoke, we started to see how much involuntary exposure happens," says Amirashkan Askari, a PhD candidate in department of chemical engineering and applied chemistry. Askari co-authored the study with University of Toronto Engineering Associate Professor Arthur Chan and  Frank Wania , a professor in the department of physical and environmental sciences at University of Toronto Scarborough. Between April 2021 and March 2022, Canadians spent $4 billion on regulated, adult-use cannabis,  according to Statistics Canada. Dried cannabis accounted for 71.1 per cent of sales, indicating that smoking is the most popular method of consumption.     "Any type of smoking, whether it is tobacco or cannabis, leaves behind a suite of pollutants that can remain in homes," says Chan.