As noted in an earlier post, right now it's the wild west out there when it comes to masks. It seems they are hyped based on everything except how well they work filtering virus-size particles.
Now, the American Society for Testing and Materials (ASTM) has come to the rescue with a new set of standards for "barrier face coverings," known to most of us commoners as masks. If you follow that link you will be required—for reasons unclear to me—to go through a registration process that includes providing your address and phone number and verifying your email before you can see the standards.
I registered and got the document so you don't have to. There are basically three important parts to the standard, requirements for design, testing, and labeling.
Design Requirements
Masks must cover the nose and mouth. They can't have valves or other things that allow unfiltered breath to escape. They have to say if they're one-size-fits-all or sized for different faces.
They also must be tested for leakage. Manufacturers must include a self-declaration "that the product reduces leakage around the perimeter or other areas of the product based upon an analysis of the product design." It says this will be determined using a leakage ratio determined by Test Method F3407—whatever that is. But it doesn't seem that that this information ever makes its way to the consumer.
Performance Requirements
Under this standard, masks are tested for filtration efficiency and airflow resistance. Filtration efficiency is tested using salt particles as in a study reported in an
earlier post. There are two levels of performance: Level 1 with 20% filtration efficiency or better, and Level 2 with 50% efficiency or better.
It seems odd that there isn't a Level 3 with a higher efficiency. As a consumer I'm not reassured by the idea that a mask I'm buying would let through 50% of the virus aerosols coming at me.
Airflow resistance is tested, I believe, with a rig that measures how far water is pulled up a column with a given amount of suction. The Level 1 standard is 15 mm of water or less. Level 2 is 5 mm of water or less. That doesn't mean a lot to me, but they say that "Airflow resistance in range of 5 to 15 mm H2O can be perceived as difficult for long-term wearing by some individuals, including children or adults that have specific medical conditions that cause difficulty in breathing."
It's also not clear if these levels are independent. Can you have a mask with Level 2 filtration but Level 1 airflow? And again, as consumers do we get to know this?
Labeling Requirements
It seems the answer is no. The only thing performance-wise that's required to be printed on the product is "MEETS ASTM F3502." Other requirements are size, manufacturer, lot, etc. This is disappointing on a couple of levels.
First, that's a label only an engineer could love. Nobody but engineers or geeks like me who look up standards documents even knows what ASTM F3502 is. That label is literally meaningless to most consumers, except as an indication that the product has undergone some kind of testing.
Second, all it tells me is that the mask is at least 20% effective at filtering virus-sized particles and probably won't bother my breathing unless I have some kind of health condition. For me that's not much of a quality reassurance.
Bottom Line
Any standards are better than no standards. But from a consumer point of view these are a disappointment. It looks like they set a very low bar to qualify for labeling that amounts to a stamp of approval. The label doesn't convey meaningful information. It would be better if they included actual results on leakage, filtration efficiency, and airflow resistance. But I'm mystified by their decision not to even include even a "level" marking when testing establishes these levels.
Who knows, maybe "Big Mask" got involved and watered down the requirements!
