Does a KN95 that says 'non medical' helps to protect against COVID-19?

Question

I saw this type of face masks on a 'building tools' store (like home depot), and on the label said, among other things in chinese and english, non medical.

In this KN95 Masks Explained mentions

These masks, like NIOSH N95 masks, provide protection from 95% of particles that are greater than .3 microns in diameter.

However do they also protect even when says non medical?

Update

I've got one and as you can see the only difference with a medical mask is the FDA label (notice the upper RHS, there is none), as pointed out by @BobE. The brand is exactly the same.

inside the cover was this paper

Here is the pic with the FDA label (notice the upper RHS, the FDA label)

Answer 1

In the US, in order for a mask to be labeled "medical", that mask must be approved by the FDA as a medical device. With so many new people manufacturing masks coupled with the public demand for masks, it is likely not profitable to delay to seek FDA approval. The FDA also is unlikely to approve a new manufacturer's mask without ASTM testing.

Thus, it is possible that these KN95 masks are a functional equivalent to N95 masks approved for medical use, but have not yet been approved by FDA.

Keep in mind that that coronavirus particles (fancy scientific name “virions”) are spheres with diameters of approximately 0.125 microns (125 nm). The smallest particles are 0.06 microns, and the largest are 0.14 microns. (Lancet)

The article here may be useful to help you sort through the efficiency of masks.

Answer 2

Typically for an N95 mask to be considered "medical grade" it must be compatible with a sterile environment, such as by filtering both inhaled and exhaled air.

Surgical masks provide some filtration of exhaled air, which is why they're useful in surgury (e.g. keep saliva off an operating region). I have an N95 mask advertised for environments with dust and smoke (e.g. to wear while working with soil to prevent Legionnaires' disease). In these environments there's no need to filter air on the exhale; such filter would add to cost and increase the effort to exhale. For this reason "medical grade" N95 masks may be more expensive and more humid than those with a valve for exhaling air.

Unless there's a significant difference in how the filters are manufactured, then these masks are effectively the same for filtration of inhaled air. If medical grade masks were able to filter 99% of particles within a given size range then they would be N99 masks, not N95 masks.

However as @BobE mentioned "medical grade" likely must pass further tests and conform to other regulations (and perhaps requiring more expensive quality control measures) which would drive up the prices and could delay a product from reaching market.

Answer 3

The mask protects people from the person wearing the mask. In surgery, my colleagues and I wear a mask to protect the patient's open wound from me. Do not make the mistake of thinking that you, as the mask wearer, are conferring a degree of protection that provides safety.