Health officials across the country are advising Canadians to ditch single layer cloth masks in favour of masks that offer better protection, but research on whether N95 masks are the better choice still isn’t clear, according to an infectious disease expert.
Dr. Lynora Saxinger, an infectious diseases specialist and associate professor at the University of Alberta, said research is not conclusive enough to say N95 masks are superior to all other types of masks when it comes to protection against COVID-19. However, whether or not the mask fits properly makes a huge difference.
“I would never dissuade someone from using a respirator mask, especially if they can afford one. Use the best mask that you can afford that fits you the best,” Saxinger said. “But if we can actually use respirator masks, making sure they’re really fitted well becomes important.”
An N95 respirator is a respiratory protective device that is designed to achieve a very close fit to the wearer’s face to filter airborne particles, with the edges designed to form a seal around the nose and mouth. But they aren’t meant as a one-size-fits-all option.
Medical staff working with COVID-19 patients are required to wear an N95, but they’re also required to have their masks fitted through a formal process — a simple visual assessment of gaps isn’t enough, Saxinger said.
“I see a lot of really bad N95 mask wearing, where the fit of different brands on different faces can vary a huge amount,” she said. “The problem is there are a lot of masks of varying quality, and people are scrambling to buy whatever they can. There isn’t really an opportunity to try them on.”
Construction and hardware stores carry N95 masks with a valve attachment, but those are meant to filter out dust particles from carpentry projects, not COVID-19.
“If you’re infected, and you’re in a mask with an airflow valve, you’re just spraying it all over,” said Saxinger.
A study done by the U.S. Centers for Disease Control in February found exposure to potentially infectious aerosols decreased by about 95 per cent with tightly fitted masks. For better protection, the study suggests wearing a cloth mask over a medical procedure mask, and then knotting the ear loops and tucking in extra material closer to the face.
Wearing a mask that isn’t properly fitted allows air to flow around the mask itself, meaning a poorly fitted respirator mask may actually become a hazard, said Saxinger. If the mask has good filtration, there should be some resistance to airflow.
“The odds are that if it’s a very comfortable mask that doesn’t get really humid behind it, it probably isn’t a very good mask.”
A September report from Alberta Health Services’ scientific advisory group found there is “insufficient evidence to demonstrate a significant difference in documented health-care worker infections when using N95 respirator versus medical surgical (masks)” overall. The report also found the possibility of aerosol transmission alone is not sufficient to mandate the use of N95 respirators.
Dr. Deena Hinshaw, Alberta’s chief medical officer of health, said during Tuesday’s news conference that a cloth mask must have at least three layers with one layer as a good filtration mechanism, and all types of masks must have a good fit around the face to be effective.
“So whether somebody has a cloth mask, medical mask or an N95 — if it’s worn slightly below the nose, it won’t be effective,” Hinshaw said.
Four hardware and personal protective equipment suppliers in Calgary told Postmedia demand for N95 or the Chinese-standard KN95 masks has increased slightly, but it shouldn’t be difficult for people to find one in most local stores.
When it comes to infection control, experts say understanding how the virus is transmitted is essential to slowing spread.
At the beginning of the pandemic, health officials recommended frequent hand washing and physical distancing to break transmission through droplets and contact. But as time went on, outbreaks supported a longer range pattern of respiratory spread as well, Saxinger said.
For example, if two people are in close quarters in a crowded bar yelling at each other over loud music, COVID-19 could be spread both by droplets and airborne transmission, she explained. Different settings and different circumstances can affect spread, but the topic of transmission itself has become “hopelessly polarized” without more research.
“There’s not a consensus that aerosol is the dominant mode of transmission, although most infection control people acknowledge that it’s part of transmission … They just didn’t want to make it a focus because it still is a little unclear how much it contributes overall, and in what settings it contributes the most.”
Part of the reason that Omicron is more transmissible is that long-range transmission is happening more often through aerosol dispersion, Hinshaw said.