The recommendation to use an N95 respirator to reduce the impact of a chemical gas exposure is comparable to the use of a placebo in patient care. Any improvements in conditions are only perceived and are not real.
N95 respirators use a filter of densely woven fibers that can stop aerosol particles through impaction, interception and diffusion as the air being breathed in passes the mesh. They are 95 percent efficient in stopping particles down to about 0.1 micrometers (microns) in diameter. So they work well on tuberculosis, and other bacteria, that range in size from about 0.3 to 20 microns.
Gas molecules, however, range in size from only 0.0003 - 0.006 microns [0.3nm - 60nm]. As a result, gases like oxygen, chlorine, hydrogen sulfide and ammonia can all pass freely in the spaces between the fibers in an N95 mask.
Whilst size comparisons between viruses and bacteria can be useful to researchers, it is also useful to compare the size of SARS-CoV-2 to other things that are encountered daily. For example, a dust mite is typically 200 µm in size. If we take a 100 nm SARS-CoV-2 particle, this makes the dust mite 2000 times larger
For example, respiratory droplets are typically 5-10 micrometers (µm) in length; therefore, it can be inferred that an individual who ingests, inhales, or is otherwise exposed to SARS-CoV-2 positive respiratory droplets can be exposed to hundreds or thousands of virus particles which increases the probability of infection
Difference Between Micron and Nanometer
1 micron = 1 μm = 10-6 m
1 micron = 1/1000 mm
1 nanometer = 1 nm = 10-9m
1 nm = 1/1000 μm
The average human cannot see anything smaller than 40 microns in size. A strand of human hair is around 75 microns or 75,000 nanometers in diameter; human red blood cell is about 6.2 – 8.2 microns or 6,200 – 8,200 nm across; the size of bacteria is about 1,000 nanometers or 1 micron.
