Use of an N95 mask is seen as overkill for the public and even for most doctor-patient interactions. Photo / AP
Use of an N95 mask is seen as overkill for the public and even for most doctor-patient interactions. Photo / AP
COMMENT:
Do I need an N95 mask to stop myself getting the coronavirus? I work in essential services and only have access to a surgical-type face mask. Is it good enough?
A: The answer is no to the first question, and a probable yes to the second one. Surgical masks areusually made from polypropylene, the same plastic used in reusable shopping bags. These masks form a water-resistant barrier between our mouths and noses and the invisible Covid-covered mucus particles seeking to infect us.They also serve as a physical reminder for us to not touch our faces, something that humans do all the time, subconsciously.
While manufacturers of surgical masks are careful not to say that their masks stop viruses, early evidence from Singapore, Taiwan, and other places that have dealt with Covid successfully suggest the humble surgical mask, combined with frequent hand washing (or alcohol rub 'hand hygiene'), can prevent the vast majority of Covid infections, even in higher-risk groups like healthcare workers.
In a hospital setting, surgical masks are currently considered adequate protection for anything short of aerosol-generating procedures, such as CPR, suctioning, or the insertion of a breathing tube. These procedures, where the clinician is intimately exposed to the patient's airway secretions, are vastly higher-risk than what regular folks might encounter. For anything short of these invasive procedures, surgical masks are thought to perform admirably. I currently use them in the ED for patient care, always alongside frequent hand-washing or alcohol gel application.
Should a person in the community use a surgical mask?
That's not a simple answer. My thoughts on it are as follows: if there are any mask shortages in healthcare, then absolutely not, because those masks should be used by healthcare workers to look after the rest of us.
If there's an abundance of masks, then the proper use of face masks (put on and taken off correctly, and with good hand hygiene before and after) likely isn't harmful and may well be beneficial in preventing people touching their own faces and inoculating themselves.
N95 masks are named so because they block 95 per cent of inhaled particles 0.3 microns or larger.
"Only 95 per cent? That doesn't sound so great." I already hear you saying.
But even though viruses are vastly smaller than the pore size of an N95 mask, it really doesn't matter clinically. Viral particles don't infect you by themselves. They travel by the millions, and their taxis of choice are globs of coughed up mucus that are enormously large compared to them, but still invisibly small to us.
N95 masks do a great job of blocking these relatively large mucus droplets. Such a great job in fact, they're recommended for use when a doctor is intubating a patient or performing another high-risk airway procedure. In the emergency department, I only use them for invasive airway procedures, and not for regular ED patient interactions.
Guided by the best evidence that's available to us, it seems N95s are overkill for even the majority of doctor-patient interactions, and certainly are inappropriate for use by the public. N95s should be 'hoarded' only for use by specialist staff performing airway procedures. There's no good evidence yet from Covid, or other past coronavirus epidemics, that the level of filtering efficiency they offer is necessary, or more effective than surgical masks.
One final tip:
Covid does not leap into our bodies. It is not carried on a mosquito like dengue fever, and does not contaminate the air for hours like measles. In the vast majority of cases, we give Covid to ourselves by touching our faces, or through prolonged close contact with people who are infected. The best thing you can do is remember to wash your hands, and not touch your face.
