We all know that N95 Masks are reserved for front line healthcare workers and ordinary people can’t buy them. The next best thing is KN95 masks that have almost identical performance and these can be purchased by the public. The problem is there are many fake imitation products on the market and it’s difficult to know which ones are actually good.
While I don’t have any lab equipment, I can do some basic quality checks. I performed some destructive testing on some $2.49 KN95 masks from Fry’s that claim to pass the Certification Standard GB2626–2006 which is a Chinese Certification for masks that is almost as good as the NIOSH N95 Certification.
My tests show that these are probably legitimate. It passed the following tests.
- Good snug fit with minimal leakage around the face
- Can’t smell things when wearing mask
- Mask can hold water without leakage
- Mask has 5 layers
- Mask material well melt but not burst into flames
- Middle layer is an electret material that has traps tiny particles with static electric charge
N95 Masks versus Cloth Face Cover Masks
There’s a world of difference between N95 Certified Masks and plain Cloth Face Cover Masks. The National Institute for Occupational Safety and Health (NIOSH) performs certification tests on N95 Masks. In a 2010 Study, NIOSH tested the filtration efficiency of N95 Masks and Cloth Masks. It shows that N95 Masks block 95% to 99.9% of particles between 20 nm and 1000 nm. Cloth masks block between 10% and 60%. The typical performance difference is 99% for N95 vs 20% Cloth.
Effective Strategies for Stopping COVID-19
As you can see, Cloth masks are not even in the same league. The only thing they’re useful for is situations where two people are facing each other within 6 feet. Cloth masks can slow the air velocity down and reduce the amount of viral droplets from talking. Talking emits 10x more viral particles than regular breathing. This is why you see politicians who advocate mask usage not wear a mask when talking into the camera and they all say “I’m not within 6 feet of other people” so I don’t need a mask.
But 80% of COVID transmission comes from 10% of the population during superspreading events which happen outside of 6 feet face-to-face interactions. Andy Larsen sums up common places where superspreading events happen. Examples include Buses, Restaurants, Call Centers, Choir halls, and Zumba rooms. All these examples involve air recirculated by Fans and Air Conditioners. The Bus example was notable because nearly all the people sitting next to an open window were spared from infection because they were able to breathe fresh air.
So to stop superspreading events, Cloth Masks have minimal effect because of their poor filtration efficiency and poor fit. N95 or KN95 Masks will work extremely well but it’s unlikely that a large percentage of the population will use them or be able to acquire them for long sustained periods. But Masks like the KN95 I reviewed are useful for high risk situations like visiting grandparents or in confined spaces with many people.
The only thing that can effectively stop these events on a large scale is better ventilation standards with much higher air exchange rates or Air Conditioning systems with filtration or decontamination systems. Ventilation fans with high CFM can certainly help a lot in mild temperature regions and it would be a very low cost solution.
