The Public Health Agency of Canada (PHAC) is currently recommending medical masks to the following groups:
When choosing a mask, there are three top-level categories to choose from, non-medical masks, medical masks and respirators. As non-medical masks are not required to conform to any standard, the protection they offer is generally inferior to that of medical masks and respirators and is often highly variable from one product to the next. Medical masks and respirators provide superior protection against Covid-19 as compared to non-medical masks. SafeTMed does not sell any non-medical masks given the current PHAC recommendations.
The terms medical mask and surgical mask are generally used interchangeably.
Both medical masks and respirators sold in Canada have to conform to standards, but the standards set for respirators are generally more stringent. A respirator is designed to achieve a very close fit to your face and has very efficient filtration of airborne particles. A medical mask is looser-fitting facial device with less efficient filtration of airborne particles, although it still offers significant protection against Covid-19.
The American Society for Testing and Materials or ASTM, has published three levels for medical masks based on increasing standards of filtration efficacy at different particle sizes, differential pressure resistance, fluid resistance and flammability. ASTM level 3 masks are the highest performing with the best particulate filtration efficacy and the best fluid resistance. However, ASTM level 2 and level 3 masks differ only in their fluid resistance. ASTM level 1 masks offer ≥ 95% filtration efficacy at both 3 μm and 0.1 μm particle sizes, whereas ASTM level 2 and 3 masks are rated at ≥ 98% for each. This data is summarized in the table below:
| ASTM Level 1 | ASTM Level 2 | ASTM Level 3 | |
|---|---|---|---|
| Filtration 3 μm particles | ≥ 95% | ≥ 98% | ≥ 98% |
| Diff. pressure (mmH2O/cm2) | < 5.0 | < 6.0 | < 6.0 |
| Filtration 0.1 μm particles | ≥ 95% | ≥ 98% | ≥ 98% |
| Synthetic blood resistance (mmHg) | 80 | 120 | 160 |
| Flammability | Class 1 | Class 1 | Class 1 |
An ASTM level 2 medical mask is an excellent choice for people where for whom the likelihood of exposure to fluids is negligible. If fluid exposure is possible or probable, ASTM level 3 is the preferred choice of the medical mask categories. ASTM level 1 masks offer slightly inferior particulate filtration efficacy and can be selected if cost is a primary consideration.
A well-fitted respirator offers superior protection than even an ASTM level 3 medical mask and should be selected by those who are at very high risk of exposure to COVID-19 because of their living situation or are at very high risk of more severe disease or outcomes if they get COVID-19 due to their personal circumstances such as age and prior health conditions.
Most medical masks and respirators are rated for single use, however if not visibly soiled, wet or broken, these can be worn many consecutive hours.
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