Person wearing a face mask in a cloud of dust

The world of masks and respiratory protection is so complicated that it’s hard to keep up unless it’s your day job! Luckily it is our day job at Breathe99, and we’ve laid out the basics in this four-part Mask Buying Guide.

This post runs through common situations where people need respiratory protection. The other parts of the Mask Buying Guide can be found here:

Masks have been used for centuries by humans for disease control, but there are many other reasons to need respiratory protection. Most of these other reasons are seasonal, such as wildfire smoke, pollen, and smog. Of course there are also occupational (hopefully your employer has this covered) and household reasons like sanding that create a lot of dust.

This post will focus on filtering particles, specifically any little bit of a solid or liquid that can float in the air, down to 0.1 micron in size. To understand what kind of respiratory protection you need, it helps to understand how big certain particles are. The graph below shows the size range of common contaminants compared to the width of a human hair. It’s also important to know that gases and volatile organic compounds are much smaller than 0.1 micron, and require a completely different filter than the type of particle filter we are talking about here. So if you can smell perfume through your N95 respirator don’t be alarmed. It’s just not what it’s designed to filter. Here’s a great explainer about activated carbon if you want to know more.

Size comparison of micron-level particle contaminants

We’ll get to use cases shortly, but one more important thing to know is that when it comes to filtering particles, only the size of the particle matters, not what it’s made of! It may not seem intuitive that a sneeze droplet has the same chance of getting through a filter as a piece of dust the same size, but it’s true! So don’t get too hung up on what particle you want to filter, but rather how small. But don’t take our word for it, take it from NIOSH itself - a particle is a particle 

Without further ado, here are the most common reasons to need respiratory protection and why.  

Infectious disease prevention

Experts believe that proper widespread use of face coverings helps reduce the transmission of Covid-19. What is “source control”? It means that your mask is protecting other people in case you are a source of contagious disease. This method of disease control is low-tech and affordable, but only effective if most people comply. The type of particles here are the droplets  that you exhale from your nose and mouth (the really small “aerosol” droplets are less than 5 microns large). These carry viruses and bacteria, which can spread to other people.

In terms of protection, a fabric or surgical mask will catch many of your exhaled droplets. If you are concerned about protecting yourself as well, you will need a respirator-style mask with a full seal. That way, with the proper fit, all of your inhaled and exhaled air will be filtered. 

Wildfire smoke

Seasonal wildfires are becoming more severe and prevalent on the West coast of the United States and in other parts of the world. What’s in the smoke depends on exactly what is burning, but a major constituent is very fine particles less than 2.5 microns, or PM 2.5.  For effective protection against wildfire smoke you need a well-fitted respirator-style mask, such as our B2 Mask, which has a full seal so that all of the air you breathe is filtered. A cloth or surgical mask will do nothing in this case. 


Seasonal allergy masks have actually been a niche type of face mask for a while. They are well-fitted face masks made of dense cloth or foam, which reduce the amount of allergens you breathe. Pollen particles are quite large (a whopping 10 microns!), and therefore very easy to filter. If you are particularly sensitive, you should consider a fully-sealed respirator to block out more allergens.  


Smog is very similar to smoke - it is made of very fine particles and gases and requires a fully-sealed respirator with high quality filters. It may be beneficial to have a respirator with a carbon filter to capture gases as well. 

Hobby Work

Finally, long before the Covid-19 pandemic, carpenters and construction workers have been wearing respirators for dust (sometimes a looser, mostly-sealed version). In fact a lot of dusty handiwork around the house is best done wearing a respirator. For example cutting wood, installing insulation, demolition, cleaning the attic, and some gardening. Long-term respiratory protection is not just for professionals - every little bit counts! If you purchase a high quality reusable respirator like B2 Mask because of today’s pandemic, you might find it come in handy on occasion around the house as well. 


Found this useful? Share this link with a friend!

Questions or comments? Reach out to