The wrong fine dust mask, or one worn incorrectly, is only a waste of money.
I recently published an article discussing the air quality in Korea and how to deal with it. After sharing the post on Facebook, a lot of people disagreed about the usage period of disposable masks. Many people said that they use them for a few days in a row, and that they are still effective for a few days of heavy pollution.
I realize there is a lot of confusion out there as to how specifically the masks work, and I want to discuss which masks are the best, how long they last, and more, in this post. Which masks actually protect you from fine dust, how long do they last, and how should they be correctly worn? What is the best fine dust mask?
Different types of masks:
‘Common surgical masks are meant to catch the wearer’s own bodily fluids, such as saliva and nasal discharge, and prevent any infectious liquid droplets from spreading to others. They are not designed to protect you from inhaling airborne bacteria, viruses and fine particles.’¹
Surgical masks such as the ones above are not effective against fine dust.
Surgical masks are one of the most common mask types that I see people wearing every day. While many people wear these to protect both themselves and others from sickness, there are also many who wear them with the assumption that they protect from fine dust. This is not only untrue but something that is potentially harmful to assume. Surgical masks have two straps that sit behind your ears, and these are ineffective against fine dust for a number of reasons. Not only is the material not meant to prevent the penetration of fine dust, but the masks also don’t create a seal on the wearers face. Fine dust can simply enter the mask through the gaps around the wearers face.
Respirators, on the other hand, are masks meant to prevent fine particles from entering the body of the user. These respirators are rated N95+ (with the number representing the percentage of particles prevented by the mask. I.E, an N95 mask is effective at preventing 95% of particles from passing, while an N99 mask is effective against 99% of fine particulate matter).²
R rated masks (R95+) are also available and are resistant to oil. However, these aren’t needed for the general user in Korea. If you bike often on roads (behind other vehicles especially), then consider purchasing R masks to protect from the harmful gasses emitted by the vehicles sharing the road.
It is worth noting, however, that KF and N rated masks only protect you from fine dust. They do not protect from other ozone pollution such as gases. ‘N95 masks do NOT protect you against chemical vapours, gases, carbon monoxide, gasoline, asbestos, lead or low oxygen environments.’³ If you want to learn more about the different pollutants in the air, this article covers everything you need to know.
How long can I use a single mask for?
‘NIOSH states that it is not always necessary to dispose of the FFR (filtering face-piece regulator) the first time it is removed. In most workplace situations, an FFR can be reused as part of an employer’s respiratory protection program. Safe FFR reuse is affected by a number of variables that impact respirator function and contamination over time, says NIOSH. Unless the respirator manufacturer identifies a specified duration of use—for example, single use only, or the employer’s respiratory protection program excludes reuse—users can wear an FFR until it is damaged, soiled, or causing noticeably increased breathing resistance.
However, there are limitations for reuse. Perhaps most importantly, the FFR should be used and reused only by the same wearer. Also, between uses, the FFR should be stored in a way that protects it from damage, dust, contamination, sunlight, extreme temperatures, excessive moisture, and damaging chemicals. In addition, since most disposable FFRs do not have solid frames, they should be stored in ways that prevent deformation of the facepiece, straps, and exhalation valve, if present.’⁵
It is also very important to remember that the reusing of masks depends heavily upon a few factors. The air pollution, humidity, and amount of physical exertion. After a day of high pollution (such as days with an AQI rating over 250), masks should only be worn for a single day. However, on days of lower AQI ratings (such as 50), these masks can be reused for a few days or until breathing becomes difficult. Physical exertion can also vary the lifespan of a respirator, and if you are running or biking with a mask, consider replacing it every day or two – even in days of light pollution. Finally, humidity greatly affects the effectiveness of a respirator, as once a mask becomes damp it quickly loses its filtration qualities. On high-humidity days, change your respirator every day.
My personal mask preference is a reusable Cambridge Mask.
When to Throw Out the N95 Mask
As the N95 mask gets clogged, it becomes more difficult to breathe. When this occurs, throw it out and use a new one. Discard the mask if it is wet or dirty on the inside, if it is deformed, or if the filter is torn. A deformed mask may not fit properly. An N95 mask cannot be cleaned or disinfected.⁶
In short, respirator masks can be reused. However, after the first usage (or after 8 hours), they are no longer guaranteed to perform to the NIOSH standards. It is worth keeping in mind, that while masks will degrade, they can normally last a few days of light-medium usage.
A variety of factors can influence how long the respirator is usable for. Oil and humidity drastically affect the performance of masks and decrease their lifespan. If you cycle lots (on the road, behind vehicles), or are out in humid weather, you should be changing your mask regularly. If the mask ever gets wet, dispose of it and find a replacement.
It is also worth noting, how you touch the mask will affect how effective it is. When putting on and taking off the respirator, make sure not to touch the material in front of your face (either on the outside or inside of the mask). Instead, use the straps to adjust the mask and put it on. Before removing the mask, make sure to wash your hands as otherwise fine dust particles can transfer to the respirator.
When storing the mask, make sure it isn’t placed in the sun, and that there is nothing around to put pressure on the mask and deform it. Deforming the mask will reduce its effectiveness by decreasing the fit and ruining the seal. Further, have one mask per person, and don’t share masks. Once worn, the mask is shaped to the face of the wearer. Allowing others to wear the mask will break this shape and will once again, decrease effectiveness.
KF ratings vs N
The NIOSH only certifies masks which surpass a rating of N95. No mask preventing less than 95% of fine dust particles will be given a rating. As such, you can be sure that you are getting a quality product if it has the N rating. KF masks, on the other hand, are rated by KFDA (The Korean Ministry of Food and Drug Safety, now named the MFDS) and are unique to Korea. These masks are rated similarly to the NIOSH rated masks, with KF80 being the minimum rating. However, with KF80 rated masks only preventing 80% of fine particulate matter from penetrating, it is recommended that you wear KF94, N95 or above.
When NIOSH and KFDA masks were compared to each other, both performed well. ‘All tested quarantine masks satisfied the maximum penetration criterion of 6% (KF 94)’.⁴ While similarly rated masks in both the KFDA and NIOSH systems perform similarly, it is noted that NIOSH masks perform better at higher ratings (N95+). Considering that KF ratings don’t surpass KF94, N rated masks are also capable of higher ratings and N99 should be used when possible.
NIOSH (N) masks VS KFDA (KF masks). Hyejung Jung, Jongbo Kim, Seungju Lee, Jinho Lee, Jooyoun Kim, Perngjy Tsai, Chungsik Yoon. Comparison of Filtration Efficiency and Pressure Drop in Anti-Yellow Sand Masks, Quarantine Masks, Medical Masks, General Masks, and Hankerchiefs. 2014.
How To Correctly Wear a Respirator
When putting on a respirator it is important to keep physical contact with the face-piece to a minimum. When touching the mask, try to restrict hand contact to the strings. Contact with moisture decreases the effectiveness of a mask, and oil and moisture from your hands can easily affect the usefulness of the material.
Holding the straps, pull the mask onto your head (or over your ears) with minimum contact to the mask itself. Adjust the wire nose-piece to make sure that it fits snugly and that there is no gap around your nose. Finally, perform air pressure checks to make sure that the mask isn’t leaking anywhere.
How to Make Sure the Mask Fits
Do a user seal check, including both positive and negative pressure checks, to verify that you have correctly put on the mask and adjusted it to fit properly.
- Negative pressure check
Place both hands completely over the mask and inhale sharply. Be careful not to disturb the position of the mask. The mask should pull into your face. If air leaks around your face or eyes, adjust the nosepiece and straps and repeat the positive pressure check.
- Positive pressure check
Put your hands over the mask and breathe out sharply. If your mask has an exhalation valve (like the one pictured above) be sure to cover the exhalation valve when you exhale. No air should leak out of the mask if it fits properly. If air leaks out, re-adjust the nosepiece and straps and repeat the negative pressure check.⁷
If both of the pressure checks succeed without air leakage, then the mask is protecting you from fine dust! If on the other hand, air leaks no matter what you try, consider purchasing a new mask in a different size. It is worth mentioning though, that these masks aren’t designed for people with facial hair or for children. Children’s masks are available, but rarely are they as effective as adults masks. Facial hair will also reduce the effectiveness of respirators and there really is no other way around this except to remove the hair.
Which Fine Dust Mask is Best?
Unless you have a specific need for a moisture resistant respirator, any mask of KF94 or N95 plus is very effective at stopping particulate matter from entering the respiratory system. N99 masks are of course better, however, they are also harder to find.
There are also masks available that can be used for longer periods of time. Masks such as the Cambridge ones last over 200 hours and are rated N99. These masks are more expensive than disposable ones, but for the extra length of use they are often worth it. There are many competitors out there such as Vogmask and Respro, and these masks are also highly regarded. While I have no affiliation with any of these companies, I personally use a Cambridge Mask and highly recommend it. From my own research I found it to be vastly superior to Vogmask as it also prevents the penetration of 99.7% of bacteria and viruses.⁸ Cambridge Mask also had more extensive testing and as such, I trusted it more. Respro is an option that I didn’t look much into as the availability at the time of my purchase was limited. If you want a reusable mask, then Cambridge Masks are the way to go.
If you are not interested in reusable masks, then there are also many great disposable options available. While any mask with an NIOSH rating will perform well, there are many options available. 3M masks consistently perform well and are recommended by many. 10 packs of these masks can usually be purchased and these packs allow for a few weeks of use.
Many KF rated masks can also be found, and while these are still effective, most KF masks are only rated at 80. The best that KF has to offer is only KF94, and while 94 is still very effective, I feel far more comfortable knowing that I am wearing an N99 or N95 mask. If a mask doesn’t have a KF or N rating, don’t even bother purchasing it. The other masks that are available are usually for bacteria, and they are made to prevent the spread of sicknesses. These masks will do very little to protect you and aren’t worth purchasing.
There are many other masks available, and many of them offer great dust protection. Really, the NIOSH and KFDA ratings are the key to finding an effective mask. From there, it is a matter of finding the best fit for you. To keep this article within a reasonable length however, my broad recommendation is an N95+ rated 3M respirator. If you are looking for a reusable mask, then make sure to do research first and to look at other reviews. It is important to find a mask that fits correctly and is comfortable.
It is important to always consider and monitor the air quality, or really anything, that can potentially harm your health. However, it can be hard to understand the AQI (Air Quality Index) readings and what they mean. To learn more, I recently wrote this post to help with everything there is to know about air quality in Seoul. If you have any questions or comments about respirators, the air quality, or Seoul, please don’t hesitate to let me know. You can get in contact with me by leaving a comment below, or by contacting me here.
This post contains affiliate links which allow me to make money at no extra cost to you. I have no affiliation with Cambridge Masks, I am just a happy user of their product.