Canada Post says its employees will be able to wear their own N95 masks at work, but only if they wear a disposable medical mask provided by the corporation on top.
Some postal service employees doing tasks with a greater risk of catching COVID-19 — for example working in a pair to unload a van inside — are being given N95 masks, but a "fit test by a qualified professional" is required before they can be worn.
The Crown corporation drew criticism last week for refusing to let employees bring their own N95 masks to work.
It said employees had to use a Canada Post-issued non-medical cloth or disposable medical mask, or they would be sent home.
The Canadian Union of Postal Workers said research shows N95 masks offer better protection against the more transmissible Omicron variant than disposable medical masks.
Canada Post issued new guidance on masks to its employees on Thursday, saying it is distributing millions of high-grade medical masks to them. It said it expected all postal workers to receive a "level 2" mask, which has three layers, by the end of February.
A spokeswoman for CUPW said it welcomed the distribution of the higher-grade masks but said it should consider distributing N95 masks to all workers as well.
Jon Hamilton, a spokesman for Canada Post, said employees would not be allowed to wear their own N95 masks without the mask provided by the corporation on top.
"As an employee, you have to wear a Canada-Post-provided mask," he said.
Canada Post said in its memo to employees that it is required to verify the safety of N95s, and any respiratory device used in the workplace.
It said, without exception, N95 masks require a "fit test" before they can be worn.
"The fit is crucial to their effectiveness; therefore, a qualified fitter must conduct a fit test for each individual," the guidance says.
The update says that because it has more than 50,000 employees across the country, providing fit tests to everyone "is not feasible in the short term."
The Public Health Agency of Canada says medical masks and N95-type respirators offer better protection and have to meet certain standards in Canada.
PHAC says non-medical, cloth masks can be worn but don't have to meet any standards.
Michelle Johnston, spokeswoman for federal Labour Minister Seamus O'Regan, has said that nothing in the Canada Labour Code or Canada Occupational Health and Safety Regulations precludes workers from wearing a higher-quality face covering if they would like to use a higher grade of mask or respirator.