Masking Q&A: Your Questions Answered
Authors: Ifrah Ahmad, Katelyn Miyasaki, Claire Alexander, David Richter, Ishika Agarwal, Corianne Devine-Spears
What is a respirator mask, and why should I wear one?
There are many different kinds of masks including cloth, medical/surgical, and respirator grade masks, also known as respirator masks or simply respirators. Ideally, you should use respirator masks certified to N95, CA-N95, FFP2, or equivalent standards from other countries, or more protective standards such as N99, FFP or P100. The next best are the KN95 and KF94 standards. Generally headloop masks seal better and are easier to wear for longer than earloop masks [1]. (archive).
Respirators such as N95s are much more reliable personal protection than medical masks because they have more effective filters and form a tight seal, preventing unfiltered air from leaking in and out [2,3]. To work well, respirators must fit your face; see “How do I know if my mask fits?” below.
We recognise accessibility concerns and recommend using the best well-fitting mask available to you. Generally, any mask is better than none, but gaiters and similar stretchy materials are ineffective [4].
For assistance affording high-quality masks, look at the question “Where can I access masks if I can’t afford to buy them?” below.
What about masks for my kids?
While NIOSH does not currently certify respirators specifically for children, there are masks in extra small or kids’ sizes with filtration abilities that meet N95-level filtration standards (https://www.projectn95.org/kids-mask-guide/), including the Flo Mask (https://www.flomask.com/). KF94 masks often have small sizes that may provide a good fit for kids. Use the best mask you can find that fits your kid’s face with no leaks. A chart of masks by size or vertical mask length may be useful [5,6]. For example, Canada Masq makes a CSA-approved respirator available in an extra small size [6].
There are also some mask recommendations and community-sourced mask databases that may help you find masks that are likely to fit your face (https://www.projectn95.org/mask-size-guide/, https://www.projectn95.org/collections/kids-masks/, https://www.youtube.com/watch?v=s3-Hf6wnPds).
Where can I access masks if I can’t afford to buy them?
Mask blocs are grassroots mutual aid organizations that provide free masks and often other supplies such as air purifiers and COVID tests to their communities [7,8]. One useful resource for finding local mask blocs is https://maskbloc.org/. Your local mask bloc may stock masks at libraries or community centers and may also be able to mail you masks directly. N95 respirators can also sometimes be found at local health clinics, pharmacies, and organizations. In the US, you may be able to find such locations via the CDC website [9]. Another alternative to the cost of disposable masks is to invest in an elastomeric N95 or P100 respirator [10] which has a higher upfront cost but is cheaper in the long term, as the mask last 5 years or more and the filters can last for up to 6 months depending on the setting and frequency of usage.
How do I know if my mask fits?
If you can feel air leaking around the edges of your mask when you breathe in or out, or if your eyeglasses fog significantly when you breathe out, your mask may not fit well enough. WHN has an article on mask fit here with directions for a basic test: https://whn.global/mask-fit-matters/ [11].
You can also check the fit of a mask using a qualitative fit testing kit, which uses aerosolized flavor compounds. If you can taste the flavors, then your mask is not sealed properly. Most accurately, you can use a quantitative fit testing tool if you have access to one [12–14].
You may need to test several types of masks to find one that will fit your face well. There are also some mask recommendations and community-sourced mask databases that may help you find masks that are likely to fit your face [5,15,16].
Should I use a vented mask?
Vented masks allow exhaled air to exit the mask without being filtered, which makes breathing easier but lets particles through. Inhaled air still passes through the filter. For protecting people around you from the possibility that you are contagious, look for unvented masks. Vented masks are designed to protect the wearer, but may still offer protection to others around you as well as or better than a surgical mask [17,18]. However, vented masks are easier to wear during exercise or other high exertion and might be easier to tolerate for people with certain respiratory conditions.
What’s the best mask for wildfire smoke?
For wildfire smoke, N95 masks will protect against particles in the air but not against gases. N95s are enough if the Air Quality Index, or AQI, from smoke is no worse than “Hazardous”. When working in areas with worse smoke or in the actual burn scar, you are best off with a P100+multigas respirator [19], which can also filter out harmful gases such as organic vapors. Organic vapor respirators come in several levels and can be found at your local hardware store. However, the highest level (P100 + multigas) respirators and cartridges are typically available only through specialized industrial or laboratory safety suppliers.
Can I reuse a mask?
Yes, masks can be used for up to approximately 40 hours, but it is advised to leave them out for a few days in between wear in order for them to be sanitised, preferably in a cool, dry place. Put each mask in a brown paper bag for 72 hours in between use [20]. Keep a few masks in rotation or have a mask for each day of the week. Masks can get dirty with extended use, especially in locations with dirtier air, and will deteriorate over time. Retire masks if they get visibly dirty or frayed, if the elastic straps get too stretchy, if they develop or absorb an unpleasant smell, or if they do not provide a good seal [21].
Should I worry about microplastics?
Many high-quality masks are made of plastic materials, but this does not mean they lead to significant inhalation of microplastics. In fact, N95 respirators can actually reduce intake of microplastics by 25 fold by blocking small particles, including microplastics, from being breathed in [22]. N95s are also extremely unlikely to shed material when rubbed or adjusted on your face [23].
However, discarded masks can release microplastics into the environment, so it’s important to avoid littering used masks, and where possible use designated recycling disposal [24]. This is also a greater issue with surgical masks than with respirators [24], highlighting another reason to choose N95s or masks of similar quality.
What can I do about off-gassing from my mask?
To deal with bad smells from your respirator, simply remove it from its packaging before you expect to put it on. After 30 minutes of outgassing, volatile organic compound levels decreased by 80% in a KN94 respirator [25]. For some masks, it is best to allow them to air out for six hours or more [26]. Removing a mask from its packaging and opening it up the night before use allows any off-gassing to dissipate, preventing unpleasant odors and reducing exposure to volatile chemicals.
Should I worry about masks and nausea?
If you’re new to respirators, wearing one at home for short periods can help you get used to how it feels before using it in public.
Some people report feeling nauseous while wearing masks, but studies show that masks like N95s are not the actual cause of nausea. In most cases, the discomfort is related to other factors—such as dehydration, low blood sugar, or overheating. When people skip meals or drink less water while masked, especially during long work or school days, it can lead to lightheadedness or nausea. Additionally, the warmth and humidity inside a mask, combined with motion (like riding a bus or walking), can cause mild motion sickness or queasiness in sensitive individuals. Sensory sensitivity and anxiety can also contribute, as wearing a tight-fitting mask may feel restrictive or unfamiliar.
New masks sometimes have a noticeable smell due to packaging materials, which can trigger nausea in people sensitive to odors. Fortunately, letting the mask air out before use greatly reduces this effect—studies show that after 30 minutes, volatile organic compounds (VOCs) from new masks drop by about 80% [25].
If you feel nauseous, it’s worth trying a different mask shape, allowing the mask to air out, taking seated breaks in safe areas, and staying well-hydrated. Importantly, research confirms that masks do not cause dangerous CO₂ buildup. Blood oxygen and carbon dioxide levels remain within safe, normal ranges even during extended N95 use [27,28].
Do respirator masks trap CO₂ or make it hard to breathe?
N95 and other respirators filter out harmful particles, not gases. Although it may feel harder to breathe, multiple studies show that even during long use, blood CO₂ levels stay well within safe limits [27]. Oxygen levels also have been found to remain safe [28]. While carbon dioxide levels do rise within your mask, normal breaths are much larger than the volume of air retained within a mask, meaning that you inhale plenty of air from outside the mask on each breath.
Masks can make it a bit harder to breathe, especially during exercise or exertion, but this strain isn’t enough to cause health issues during regular use or exercise [29]. On the other hand, masks ease breathing in dry or cold air [30]. Some masks, like these Canadian respirators, have lower pressure differentials and are more breathable and comfortable.
People with asthma can generally wear respirators safely—and often benefit from reduced exposure to irritants like dust, smoke, and infectious aerosols, which can lessen respiratory discomfort. Those with severe or uncontrolled asthma may need to start with short periods of use or choose low-resistance models, but most can tolerate N95s or similar masks without breathing problems. Consult a trusted doctor if any issues arise.
How can I prevent migraines while wearing a mask?
Some people experience headaches from the tight straps on certain masks [31]. A ReadiMask, which uses a gentle self-adhesive seal instead of bands, may help. There are also many high-quality respirators in different shapes and sizes, so finding one that fits well and feels comfortable can prevent headaches during extended wear. Some retailers even offer mask sample packs to help you find the best fit (link 1, link 2, link 3).
Wearing a mask may also affect your posture, especially if you are leaning in to hear others or to be heard better, and might cause you to skip meals or become dehydrated, which can also contribute to headaches [31,32]. To avoid headaches, ensure that you eat regularly, stay hydrated, and check your posture regularly.
What should I do if my mask gets wet? What if my mask is likely to get wet, like in the rain?
Most respirators are not water-resistant. If a respirator gets wet enough, it becomes hard to breath through and less effective at filtering due to weakened electrostatic charge. If your respirator gets soaked, you should replace it. You should not wash disposable masks such as respirators or similar filters because this alters their electrostatic charge. Instead, you should sanitize your respirator by placing it in a paper bag between uses as described above.
However, surgical respirators, which are fluid-resistant like surgical masks and tightly fitted like respirators, are used in certain medical environments where fluid resistance is important [33]. Surgical respirators or elastomeric respirators with filter covers can be useful if you anticipate your mask getting damp from external conditions such as rain, as they may stay usable longer than other masks.
Physical barriers, such as a wide brimmed hat or a face shield, can keep rain off your mask, and some mask shapes are better for rain. Rigid accordion-style masks (e.g., https://www.moldex.com/product/m-series-black-masks/) tend to catch rain on the upper-facing sides, keeping the lower-facing sides dryer and the mask overall more breathable.
How do mask filters block viruses?
The filters used by masks and respirators use several physical and electrostatic mechanisms to filter particles. Larger particles tend to crash into the mask fibers (inertial impaction), while smaller ones tend to get caught when they brush past (interception) or move in zigzag patterns and collide with fibers (diffusion). Some particles settle due to gravity (gravity sedimentation), and others are pulled in by the mask fiber’s electrostatic charge (electrostatic attraction). Because these mechanisms affect different sizes of particles differently, 300 nanometer particles tend to be the ones hardest to filter out, and standards like N95 measure filtering effectiveness against 300 nanometer particles specifically. These combined methods make respirators like N95s very effective against all sizes of particles, including both tiny viruses and larger particles carrying viruses [34].
Did you enjoy this Q&A? Here are a few more resources on masking from WHN:
For a brief, visual reference, see this link: Frequently Asked Questions About Masks – WHN
For more detailed reasons on why masking is safe and important, see these resources: Yes, We Continue Wearing Masks—Here’s Why: Common Questions Answered – WHN and https://whn.global/masks-ventilation-filtration/.
References
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