B.C.'s top doctor says barriers of all kinds are crucial to prevent the spread of coronavirus — but some barriers can actually interfere with ventilation.
Provincial health officer Dr. Bonnie Henry told reporters in a press briefing Tuesday (Nov. 23) that "layers of protection" are needed to keep people safe during the pandemic.
"One of those layers is mask-wearing — both me wearing it to protect you and you wearing it to protect me," she said, adding that health officials have evidence that some masks keep both the person wearing the mask safe as well as people around them.
Wearing a face mask that fits comfortably and correctly is most important, underscored Henry. But while non-medical masks are adequate for most people, she noted that others may want to consider wearing medical ones. Medical masks and respirators sold in Canada are also required to meet established standards for filtration, breathability, and fluid resistance.
Henry added that barriers are important in certain situations. "Think about fast-food restaurants and coffee shops where that barrier does protect you from the person on the other side of it when you're at the till for example."
But types of barriers may be problematic in other circumstances, noted the health officer. "Where some of the concern has come up is around ventilation and if barriers are causing problems with ventilation," she explained.
"You may recall last fall and winter we had a lot of challenges with transmission in food processing plants. The way they're set up and the way the workers work and the challenges with wearing PPE in those situations."
WorkSafeBC assessments have shown that "appropriately placed barriers do make a difference," however. While they are not the only important layer of protection, Henry said they prevent "droplets from going back and forth."
Although coronavirus vaccines approved for use in Canada provide substantial protection against severe illness, no vaccine is 100 per cent effective. Henry stressed that along with other recommended public health measures, a well-constructed, well-fitting and properly worn mask can help prevent the spread of the virus.
Public Health Agency of Canada advice on non-medical masks
If you choose to wear a non-medical mask, it should be made of:
- multiple layers, including
- at least two layers of tightly woven fabric, such as cotton and
- a third, middle layer of filter-type fabric, such as non-woven polypropylene
- materials that are breathable
Using a filter as a middle layer in your non-medical mask can help to trap smaller infectious respiratory particles.
You can include a filter in your non-medical mask by:
- adding a filter fabric as a middle layer
- inserting a disposable filter into a pocket on the inside of the mask
- filters can be purchased or you can prepare your own using a piece of filter fabric
Reusable masks with an integrated filter layer can be washed multiple times.
Disposable filters should be:
- changed as directed by the manufacturer
- removed from the mask before washing
Find more information about the updated guidance on face masks with the Public Health Agency of Canada online.