There is a lot of talk lately on the news and social media about the use of masks for helping to flatten the curve of COVID-19 infections.
Current guidance continues to encourage everyone to stay home and avoid public outings. The CDC now recommends wearing a cloth face covering whenever it is necessary to go out in public, such as to the grocery store. The reasoning behind this recommendation is that people can transmit the virus to those around them through respiratory droplets, without knowing they are sick. It has been shown that carriers can transmit the disease either before they exhibit symptoms, or they may never show any symptoms at all.
With all the talk about mask shortages for healthcare workers and the current CDC guidance, how can you choose the right face covering for you? First it is important to understand there are different types of masks that serve different purposes. Here we are going to talk about the 3 most common in the public today: N95 respirators, surgical/procedural masks, and homemade cloth masks.
Filtering Facepiece Respirator (AKA N95 mask)
The most common of these masks is the N95 respirator. These masks must be used under the OSHA Respiratory Protection Standard 29CFR1910.134 in an occupational setting. There are several types of filtering facepiece respirators, with their specific characteristics identified by an alpha-numeric code. The letter stands for the level of oil resistance. The N stands for non-oil resistant; R represents oil-resistant and P equals oil proof. The number indicates the level of filtering efficiency of particles that are 0.3um in size. An N95 filters 95% of particles, N99 filters 99% and N100 filters 99.97%. This size particle is the most difficult to capture, therefore it is reasonable to assume that particles either larger or smaller than 0.3um will be filtered out at a higher efficiency.
For the purposes of this discussion, we will focus on N95 masks, which are the most common. When used properly, an N95 respirator will protect the wearer from particles in the environment. N95 masks must be certified by NIOSH and carry the NIOSH seal. They can be fit tested to the wearer to ensure a good seal has been reached. Because of the protection level offered, these are used heavily by healthcare staff that are working directly with sick patients. These masks are not recommended for the general public at this time. If you have N95 masks, many hospitals are asking for donations as they are in short supply. Unless you are in direct contact with sick individuals, an N95 mask is likely to be more protection than you need.
Surgical/Procedural Masks
These masks are designed to protect a patient or others around the wearer. They are loose fitting and will capture droplets exhaled by the wearer, preventing them from entering the immediate environment. The efficiency of surgical masks varies in the range of 10% to 90% capture. One major difference between N95 respirators and surgical masks is the fit. It is generally not possible to get a good seal with a surgical or procedure mask.
Current guidance states that surgical masks should be used in healthcare settings by those not in direct contact with infected patients. The level of protection for the wearer is lower compared to an N95, however it does increase protections for those in the vicinity of the wearer. Due to high demand, these masks are also in short supply and donations are welcome at many health centers.
Homemade Cloth Masks
Crafters everywhere are chipping in by making homemade cloth masks for healthcare workers and the general public. In addition, the CDC has just recently published guidance requesting everyone who ventures out in public to wear a cloth face covering. As with any homemade product, the effectiveness of these masks will vary. It is important to remember that a cloth facemask will act similar to a surgical mask, in that it will protect those in the vicinity of the wearer from contact with their respiratory droplets. These masks will be less effective in preventing the wearer from coming into contact with droplets from others. This is especially true if the mask becomes wet from use or if it is not washed after each use. In fact, there may be higher risk of exposure to the wearer when these guidelines are not followed.
If you choose to wear a cloth mask, good practice dictates that you should wash your hands before and after putting it on or taking it off. The mask should be washed after every use with soap and warm water. Do not touch the mask while you are wearing it. And finally, remember that you still need to continue with social distancing when out in public, proper handwashing, and staying home whenever possible.
These are uncertain times, and there is a lot of information floating around out there. Some of it is good advice, some of it is questionable, and some things we simply do not know the answer to yet. At the end of the day, following current recommendations from the CDC and WHO is your best bet to protect yourself, your family and those in your community. These guidelines are likely to evolve as the situation changes and we learn more about this disease. Let the healthcare workers on the front line have the supply of N95 and surgical masks so they can do their jobs. Stay home unless you absolutely need to go out. If you do, wear a cloth face covering, such as a homemade mask, scarf or bandana and follow the precautions noted above.
This is the fifth blog in a ten-part Industrial Hygiene series that we are featuring monthly. We welcome your input on the series! For additional information about the use of N95 respirators, surgical masks, and homemade masks during the COVID-19 outbreak, please email [email protected].