Health Canada says people should not use face masks that contain graphene or biomass graphene.

While the agency notes the risks to humans are not yet known, research suggests particles in the masks cause early lung toxicity in animals.

It says anyone who has worn a graphene mask should consult their health-care provider if they have shortness of breath or difficulty breathing.

Health Canada has directed distributors, importers and manufacturers to stop selling the masks and has also advised provinces and territories to halt their use.