Wearing a mask is critical to reducing the spread of COVID-19, but rigorous tests conducted on behalf of CBC’s Marketplace found that while some work very well, others offer little protection from the particles that transmit the novel coronavirus. One type of mask can even spread those particles to others.
Months into the pandemic, there are still no standards for consumer masks. So Marketplace opted to compare more than two-dozen masks to what is commonly considered the gold standard in protecting health-care workers from infectious diseases like COVID-19 — the N95 mask.
Marketplace purchased the masks in stores and online from a variety of sellers. The masks were also made out of varying materials and featured different design
Marketplace put the masks through the rigorous National Institute for Occupational Safety and Health (NIOSH) standard test, conducted at a lower air-flow regimen to reflect normal breathing. The test is usually reserved for N95s and personal protective equipment (PPE) intended for health-care workers. A standard NIOSH aerosol test measures filtration efficiency, meaning the quantity of particles the mask filters out as the wearer breathes in.
An N95 mask must have a 95 per cent filtration efficiency.
“This is the benchmark test. And it’s actually useful because it allows us to compare consumer market masks to masks that we know a lot about,” said James Scott, a professor from the University of Toronto’s Dalla Lana School of Public Health. Scott is a specialist in bioaerosols and runs the lab where Marketplace‘s tests were run.
The test pulls a constant breath of air containing tiny salt particles through the mask material. The salt particles are similar in size to particles able to contain the coronavirus that might originate from droplets expelled by an infected person’s breath, cough or sneeze. During the test, samples of air inside and outside the mask are compared to see how effective the mask is at reducing the level of particles.
Previous tests on consumer masks have commonly looked at how masks can help block particles when coughing or sneezing and prevent transmission to others. But the Marketplace test shows that certain materials make some masks better at limiting wearers’ exposure by filtering what they breathe in, Scott said.
“Even fairly low-efficiency masks are actually quite effective at catching much larger particles. But, it takes a really good mask to catch the small ones as well. And we know that the virus will travel not only on the big ones but the small ones as well,” said Scott.
For the full article, check out: https://www.cbc.ca/news/canada/marketplace-masks-test-1.5795481