Smells=/= particulate.
You can still smell farts through an N95. You can still smell dog through a vacuum bag.
However, absence of smell can mean organic vapor smell limiting. Usually from a charcoal additive to the filter (you can get it on industrial filters).
I suppose you can make the argument that vapors are smaller than particles, so the mask probably works. It's just not a scientific study.
I'm not sure this is quite right. I agree that smells do not equal particulates. Indeed you can still smell many odors with a N95 or greater mask on.
That being said to block organic vapors and particulates are not the same.
If you can block organic vapors that it usually due to a CARTRIDGE, which contains a compound such as charcoal that absorbs them. This cartridge does NOT block particulates.
Conversely, a FILTER can block particulates but cannot absorb or block organic vapors or acid gases.
With regards to the SARS CoV 2 virus, the ability to absorb and block organic vapors and acid gases is fairly immaterial, the question is can the virus (which is a particle) be filtered.
Many of the commercial respirators are designed for various industrial applications where blocking acid gases, organic vapours, etc. is an important priority. With COVID 19 the only question is can it block viral particles (particulates).
There are many combination products that do both, but the only thing that maters to us is the filtration. A cartridge with no filters is not helpful, filters with no cartridge may be adequate.
This guide from 3M is helpful:
When buying products look for the filtration designation N, R, or P 95, 99, 100. The "Color" code in the US for 100% filtration is "magenta" (although sometimes it is actually bright pink). If you get a combination device that has a cartridge with a pink cap, that usually means its p100. The cartridge has other color codes (black, yellow, green, etc.) that denote blocking various industrial hazards, but again, these are irrelevant for us in the hospital. The main distinction that matters is the "number," which determines the percentage of particulates blocked, the international standard for protection from aerosolized pathogens is 95 or greater. The "letter" refers to the filters resistance to oil (N- non resistant, R-resistant, P-proof). Resistance to oil is also not relevant in the hospital environment where we do not encounter oil-based particulates. So for our purposes, N,R, and P are all equivalent.
Your hospital may be unwilling to fit-test a product not officially approved and supplied by the hospital, but if they do an adequate device should pass the fit test (the "odor" they use is a particle not a gaseous vapour). If your device blocks other odors (pus, poop smell, whatever) it may be because the cartridge has other benefits, but that doesn't inform the devices efficacy to block viral particles.
Lastly all this is based on the NIOSH standards in the United States. There are equivalent standards in European Union (FFP designation) and China (KN designation). I am not knowledgeable of these systems, but I believe there are tables where you can look up equivalences with NIOSH standards.
