What is an N99 mask, and should you buy one?

Originally posted on Fastcompany by  ELIZABETH SEGRAN

A short guide to the world of respirator masks.

What is an N99 mask, and should you buy one?
[Source Images: chombosan/iStock, wabeno/iStock]

By now, you probably know more about N95 respirators than you thought possible. In the midst of the coronavirus pandemic, these masks have become lifesaving tools to medical personnel and other frontline workers in the fight against COVID-19. But lately, you may have spotted ads for N99 or R95 masks.

No, that’s not a typo. Here’s a short guide to what they are.

What is a respirator?

Let’s start with the basics. All of these masks are respirators, rather than surgical masks. While surgical masks fit loosely on the face, allowing particles to enter through the sides, respirators are designed to create a seal around the face so they filter out most particles. Respirators provide the best possible protection in the midst of the current crisis, which is why governments and hospitals have been racing to buy them for frontline workers. This has led to a global shortage of N95 masks.

[Photos: Snezhana Ryzhkova/iStock, firina/iStock]
What do the numbers and letters mean?Respirator names consist of a letter and a number. The letter—N, R, or P—refers to whether the mask is resistant to oil-based particles such as solvents and pesticides. (N is non-resistant; R is oil-resistant; P is oil-proof, so totally resistant to oil.) The number refers to what percentage of airborne particles the mask filters out. The R and P masks are largely geared toward industrial workers; oil resistance isn’t particularly relevant right now since coronavirus particles aren’t oil-based.

Generally, the more particles the respirator filters out, the harder it is to breathe when wearing the masks because they let in less airflow. Some respirator masks are equipped with a one-way valve that allows the wearer to breathe out, but filters out particles that are in the air breathed in. This isn’t a great option in the current crisis because if you happen to be an asymptomatic carrier of the virus, you would be breathing out virus-laden particles. Without this valve, many people report that it’s hard to wear higher filtration masks for a long time without feeling suffocated. Even N95 masks are meant to be worn for a limited period of time: After a while, particles get stuck inside the filter, making it harder for the wearer to breathe.

The classification system was developed by the National Institute of Occupational Safety and Health, which approves masks and has a running list of approved manufacturers. In non-pandemic times, respirator masks are primarily worn by workers who are exposed to dust filled with dangerous particles, such as those in construction and mining. When there isn’t an outbreak, doctors don’t require that much protection from airborne particles, so they tend to wear looser-fitting surgical masks.

Why are people only talking about N95 masks? 

As my colleague Mark Wilson recently described, the N95 was the first single-use respirator brought to market. It was developed by 3M and introduced in 1972. Over the years, dozens of other manufacturers started producing it. It remains the most popular mask on the market because it hits the sweet spot of breathability and filtration. Healthcare workers can keep the mask on while seeing patients in a COVID-19 ward without struggling to breathe.  That’s harder to do with a mask with higher filtration.

A ventless N99 mask. [Photo: Gerson]

Should you buy an N99 mask?

The average person sheltering in place should not buy N95 respirators. All N95s on the market should go to those on the front lines of the fight against the coronavirus. But when it comes to N99, N100, P99, or P100 masks, it’s a bit more complicated.

If you’re a layperson sheltering in place and only occasionally going out for essential errands, you likely don’t need one of these masks. And even though they aren’t ideal for healthcare workers because they’re difficult to breathe in, the N95 shortage has left many frontline workers desperate for any kind of respirator. One of these higher-filtration masks might be their best option.


Elizabeth Segran, Ph.D., is a staff writer at Fast Company. She lives in Cambridge, Massachusetts.  More