Some comments from Tara Mac Aulay on masks, in the context of donating to hospitals:
Cross posting my comment from elsewhere re certification standards - KN95 is not sufficient in many settings, but still useful in some. Alibaba has a lot of masks available that are unsuitable, and not many masks that are. Finding the masks that are suitable and checking if the factory has been certified under the right standards is very useful
Alibaba suppliers commonly have KN95 masks in stock, but not surgical N95 masks.
In this time of shortage, many hospitals or healthcare workers will take what they can get, but there are some serious differences.
My understanding as is follows:
KN95 masks are tested for particle filtration to a similar standard as NIOSH rated N95 masks in the US. Surigical rated N95 masks certified by NIOSH have to pass a fit test and a fluid test in addition to the filtration tests standard for N95.
KN95 masks are not rated for use in many patient contact settings, they are predominantly designed for industrial use. KN95 masks provide limited protection to the wearer in this clinical setting, some versions also provide limited protection to patients.
In addition to passing the filtration tests, masks suitable for healthcare workers to use during Covid-19 care have additional requirements:
- masks that have a valve are not appropriate for treating suspected cases. Wearing a mask with a valve is much more comfortable, as the valve allows exhaled air to escape without restriction, meaning less force is required to exhale. However, masks with a valve do not protect patients from exposure from HCWs who are potentially infected. Thus masks with a valve should only be used with patients who are confirmed infected, and for some non-clinical staff who have had limited exposure. A mask with a valve is more comfortable for the general population, you'll be able to wear it for longer, and if you're mostly trying to protect yourself rather than others, this is ok. In some clinical settings, a mask with a valve is also ok. If you are buying masks for personal use to *prevent* yourself from becoming sick, get a mask with a valve. If you want to protect others when you are sick, use a mask without a valve.
- because in many settings you'll be using a mask without a valve to protect patients, the inside of the mask will get very damp. If the mask has not been tested for liquid resistance, then this can be a problem, as the fluid may seep through the mask over time, and then again risk infecting patients. If the masks are not tested for this, the filtration efficiency may also be impacted as the mask gets wet. Surgical N95 masks are tested for 2 way fluid resistance (to ensure no fluid from patients comes through the mask to wearer, and to ensure no fluid from wearer comes through to others)
- fit is very important. Surgical N95 masks are tested for fit and escaping/incoming airflow under normal conditions of use. Without this testing, and without a mask that fits well, HCWs and patients can be exposed.
Long story short, KN95 masks are still useful in many settings, and we need those too. But what we need even more is surgical rated N95 masks, ideally certified by NIOSH as such.
It's also likely that many of the masks that are rated as KN95 would pass liquid and fit tests if subjected, but without the testing and certification, I understand why many HCWs would demand certified masks to protect themselves and their families.
She also mentioned that she expects standards in hospitals to decline over time, and that they will eventually accept other mask types for donations, if they don't already.