With the novel coronavirus outbreak globally, all of us as doctors are concerned about our safety and many of us would need to answer same to our patients.
Masks vs Respirators
In day to day language we often say mask, when referring to what are technically called respirators.
Masks are loose fitting, covering the nose and mouth Designed for one way protection, to capture bodily fluid leaving the wearer. Contrary to belief, masks are NOT designed to protect the wearer. The vast majority of masks do not have a safety rating assigned to them (e.g. NIOSH or EN)
Respirators are tight fitting masks, designed to create a facial seal. These are designed protect the wearer (when worn properly), up to the safety rating of the mask
In this post we’ll look at the difference between respirator filtering standards such as N95 and FFP2/FFP3, KN95, etc
The most commonly discussed respirator type is N95. This is an American standard managed by NIOSH (National Institute for Occupational Safety and Health), apart of the Centre for Disease Control (CDC).
Europe uses two different standards. The “filtering face piece” score (FFP) comes from EN standard 149:2001. Then EN 143 standard covers P1/P2/P3 ratings. Both standards are maintained by CEN (European Committee for Standardization).
Let’s see how all the different standards compare:
|Respirator Standard||Filter Capacity (removes x% of of all particles that are 0.3 microns in diameter or larger)|
|FFP1 & P1||At least 80%|
|FFP2 & P2||At least 94%|
|N95||At least 95%|
|N99 & FFP3||At least 99%|
|P3||At least 99.95%|
|N100||At least 99.97%|
As seen above, the closest European equivalent to N95 are FFP2 / P2 rated respirators, which are rated at 94%, compared to the 95% of N95.
Similarly, the closest to N100 are P3 rated respirators – with FFP3 following closely behind.
Other Standards equivalent to US NIOSH N95 and European FFP2
- Chinese KN95
- Australia/New Zealand – AS/NZ P2
- Korea 1st Class
- Japan DS FFRs
N vs P respirators? (Oil Resistance)
There are 3 ratings for protection against oils; N, R or P:
- N = Not resistant to oil
- R = somewhat Resistant to oil
- P = strongly oil Proof
What this means in practice, is for industrial settings, where the air might contain a lot of oil particles, if the mask isn’t P rated, then over time the oil may degrade and reduce the filter performance.
For the vast majority of people trying to reduce exposure to Covid-19, it won’t be necessary to protect against oils – this is primarily designed for industrial use settings.
Surgical vs Non-Surgical Respirators?
Alongside “regular” respirators, there are also what are often referred to as “surgical” or “surgically approved” respirators. These carry the aforementioned ratings such as N95/FFP2, but are also approved for fluid resistance. A qualification governed by ASTM F1862 – which covers the edge case in which an artery is punctured, and high pressure blood is sprayed directly at the respirator.
This type of mask is important for a surgeon, but otherwise has no extra benefit for protection from droplets of cough/sneeze which a regular N95/FFP2 masks will block also.
Surgical masks are usually three layer design, with 2 sheets of “non-woven” fabric sandwiching a “melt-blown” layer in the middle. It’s the melt-blown layer that provides the filtering capability.
A melt-blown material is also used in respirators. The melt-blown fabric is made by melting a plastic, then blowing it from either side at high velocity onto a rotating barrel which results in a fabric composed of tiny filaments.
Surgical masks also come with certification standards like- (ASTM F2100, EN 14683, or equivalent). The ASTM standard for surgical masks (particularly levels 2 & 3) are primarily focused around fluid resistance during surgery. These higher levels don’t offer much extra in the way of protection from Covid-19 under non-surgical conditions.
BUT the big question remains….
Respirators are measured by their efficiency at filtering particles of 0.3 microns and bigger and the coronavirus is 0.06-0.14 microns, So can it be filtered?
We shall discuss in our upcoming post next week..