Like me, you may have become gradually more concerned about air pollution over the years. Surprisingly, in the United States poor air quality, especially particulate pollution, is a very significant cause of death and disability. So it is natural to consider the options for an anti pollution mask. So I wanted to find an effective and comfortable solution for purifying the air that I breathe. I think I can show you a simple and comfortable solution.
The best mask to inhale purified air is one with an N100 or P100 specified filter-this will filter out 99.97% particles. A half face elastomeric format is the most effective, practical and comfortable way of delivering this. The respirator should be NIOSH approved.
As you know, there are quite a range of solutions. Some companies now even produce portable air purifiers that link to a mask. This is probably not the best approach, and I explain why below. An air purifier linked to a mask may seem like a good idea, but it means having a battery-operated fan that pushes air through a filter. This needs a battery pack and fan in a unit. This unit is often worn on a belt with a tube up to the mask supplying the air. An image of one of these is shown below in the section “Powered Air Purifying Respirators”. There are consumer versions of these, but they are not NIOSH approved. NIOSH stands for The National Institute for Occupational Safety and Health. It is part of the Centers for Disease Control and Prevention and sets the standards for masks in the US. So to be sure that you are breathing air that has been properly cleaned, you should buy NIOSH approved masks.
The design problems stem from using a fan to push air through a filter. This needs both a power supply and the fan unit. Both are unnecessary. Instead of using a fan to move the air through a filter, we can simply use the movement of air through breathing to pull the air through the filter. Effectively we our using our muscles of respiration and our lungs to move air instead of a fan and battery. Of course our muscles never run out of power like a fan does. They are also built into us-no need for external units.
This leads to cheaper, more effective solutions. I will deal with these first before turning to air purifier masks in the section “Consumer Wearable Air Purifier Masks”.
Often the focus of attention is on filter material. However, the first concern is the seal with the face. If there is not an airtight seal, most of the air will find it easier to go through the gap between the face and the mask rather than the filter material. So in the discussion below I will consider the seal between the face and the mask first. Then the filter material second.
A) Seal Between Face and Mask
There are 4 different types of mask –
1) Simple Cloth Mask or Surgical Mask-Protect others from you
These face masks have material over the mouth and nose, but no seal around your mouth and nose. They therefore good for protecting others if you cough or sneeze. However, they provide little protection for you when you breathe in. This is because the air can simply get around the sides of the mask.
2) N95 Mask (N95 Respirator) N99 Mask
These masks are referred to as “respirators” or a “respirator mask”. They are the most basic air pollution mask that give you some protection.
- These have a seal around your mask and nose. So they will protect you when you breathe in as the air has to go through the filter material the mask is made of. It is not often realized, but they offer relatively little protection to other people as there is no filter over the exhalation valve in the mask. During the COVID pandemic it was even suggested that people should wear surgical masks over 95 masks because of this.
- The seal is user defined. As the mask is a standard shape and everyone’s face a different shape, ensuring an airtight seal with the face can be difficult. The masks are adjustable-they have a medical insert over the nose for molding mask to the shape of the nose. Some people may not do this perfectly and lead to an air leak in this area. Ideally they require a fit testing according to an OSHA approved protocol to check that there is a tight seal around your mouth and nose.
These are disposable masks, that is for single use only. Although they can be reconditioned if they have not been used in a high dust environment. They have to meet CDC criteria to be certified by NIOSH.
There is a great 3 minute video showing the difference between a simple mask and a respirator here. The video to watch is the “mask v respirator” video. It also shows a fit test being done, but does not really explain it. For an OSHA mask fit test, a hood is placed over the person with the mask for an OSHA fit test. For this an aerosol that has a taste eg sweet taste is injected into the hood. If the person can identify the taste, the droplets must have got through the seal of the mask. This is because the material of the mask blocks the droplets. So if the person can taste the aerosol, the seal leaks and the mask needs a refit.
3) Elastomeric Half Face Respirator
These are generally the most comfortable masks of all to wear.
- These have a seal. The seal around the mouth and nose is comfortable because the elastomer is soft and applies pressure over larger skin area than N95 masks.
- The seal is not user defined so the seal is more reliable. The material leads to a more reliable seal as it is floppy and takes up the contours of the face. There are no operator dependent aspects of reshaping the mask to fit as there is with him and N95 respirator. However, a seal fit test is still recommended. I can wear them for hours without difficulty. It takes filters that filter out 99.97% of particles in the air with the additional option of activated carbon filters to filter out chemicals.
These are reusable masks according to the manufacture’s specifications. The main problem with these masks is a cosmetic appearance. This may be because they are mainly used in industry where it is an advantage to be able to see instantly which workers have a mask on. I feel that the manufacturers could put more effort into making masks for the consumer that blend in more.
As a choice of this type of mask 3M 6000 series Half Facepiece Reusable Respirator with P100 or P3 particulate filters would be an excellent choice. There are 3 sizes-6100 (small), 6200 (medium) and 6300 (large). Further information can be found here.
There is also a series with a quick latch mechanism for removing the face-piece without removing the head straps to talk. This is the 3M 6500QL series-6501QL (small), 6502QL (medium) and 6503QL (large). Again P100 or P3 filters are recommended-please see below for filter characteristics.
Fitting instructions for the 6502QL mask are seen in this video-
4) Elastomeric Full Facepiece Respirators
These are simply the fullface equivalent of 3. A seal fit test is recommended.
5) Powered Air-Purifying Respirators (PARPs)
These usually have hoods or elastomeric whole face pieces and are essentially a wearable air purifier. For an NIOSH certified quality PARP you would need to pay approximately $1000. This is an image of a PARP-
It is difficult to imagine walking around in public in one of these!
These are like an air purifier attached to a mask and have replaceable particulate filters. They do not usually have an activated carbon filter, UV light or other air cleaner technologies.
There are consumer versions but these are not NIOSH approved-these are outlined below in “Consumer Wearable Air Purifier Masks”
6) Other Forms of Breathing Apparatus
For completeness there are other ways of breathing purified air but these are really for industrial use-
- Supplied-Air Respirators
- Self-contained breathing apparatus
- Combination Respirators
Further information about them can be found here.
B) Filter Media
To remove particulate pollutant from the air, fibrous filters similar to those used in HEPA filters provide excellent filtration. They can remove airborne particulates and even viruses. Smaller particles are the most harmful particles for human health-especially ultrafine particles (less than 0.1um diameter. When we breathe in a particle of this size it can enter our bloodstream and so reach all our internal organs. The particle size most likely to penetrate these masks was in the ultrafine range 30 – 60 nm. Even so, the masks worked well in this range, the FFP3 mask only lets through 0.164% of particles and the P100 only let through 0.009% of ultrafine particles.
|Oil Resistance||Particle Removal Efficiency|
|N– Not resistant to oil||95-filters out 95% of particles (Europe P2)|
|R– Partially resistant oil||99-filters out at least 99% of particles (Europe P3)|
|P-Strongly resistant to oil||100-filters out 99.97% of particles|
All the various types of mask remove particulate matter from the air with fibrous filters. Some manufacture’s fibrous filters are not as effective as they should be and so it is important that you have a mask that has NIOSH approved filters.
Consumer Wearable Air Purifier Masks
These are not NIOSH approved and so not recommended. They are included to show you the different approaches that have been taken. These break down into 2 groups –
1) Air Purifying Elements Built into the Mask Itself
These do not have a separate air purifying unit or tube connecting the mask to the air purifying unit. So they look more like a fairly normal mask. An example can be seen here. However, because the air purifying element is built into the mask, it will be heavier and asymmetrical as the air purifying unit is on one side. So there will be a tendency for the mask to break the seal with the face.
The air filter unit is small, and the filter is relatively thin and so less effective than a thicker filter. No specification at all is given for the material comprising most of the mask. Do we breathe air through it like a normal N95 mask? The manufacturer does still claim that it is HEPA 12 compliant but then says “filter particle minimum 0.3um” which is unclear. Possibly they meant filter particle minimum efficiency at 0.3um. Overall customer satisfaction is 4 stars, but there are several logical and concerning 1-2 star reviews.
2) Air Purifying Unit Connected by a Tube to the Mask
This consists of a small air purifier unit that can be worn on a band around the arm, or on a belt, or even a hat. There is a tube coming from the unit to a mask. The advantage is that as the air purifying unit is separate the HEPA filter can be larger. It is claimed to be H13 compliant. The batteries are also larger, and so will last longer.
The mask simply has loops around the ears and so it will not form a tight seal of the skin. This will not matter so much when the unit is working, but if the batteries run out of power and the unit stops, there will only be the same protection as a simple cloth mask. That is very little protection. However, the main problem is the rather large white hose between the purifier unit and the mask-you would have to be quite self-confident to use one of these in public.
I would recommend a 3M 6000 series Half Face-piece Elastomeric Mask with P100 filters. You may wish to get the model with the quick latch mechanism in your size (S/M/L)-please see above. Elastomeric half face piece masks are the most comfortable. I can wear these types of mask comfortably for hours. They can also have the most efficient filters if you choose your filters well. An N100 or P100 NIOH specification NIOSH approved filter is optimal-they filter out 99.97% of airborne particles.
An air purifying system built into a mask is not necessary and may be worse depending on the filter and fit of the mask. There would also be a problem if you forgot to charge it. So my advice would be to keep it simple and buy an elastomeric mask with high specification filters.
A list of NIOSH approved particulate filtering face piece respirators can be found here.