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ASTM F3502-21 vs KN95 - The Benefits of Dual-Standards

ASTM F3502-21 vs KN95 - The Benefits of Dual-Standards

At this point, most of us are familiar with the most common mask standards and markings. N95, KF94, and KN95 masks have had ample media coverage, and these respirators are the gold standard for respiratory protection in the ongoing pandemic. 

 

However, these devices are far from perfect. Almost all of them (with the exception of public-use standards such as KF94) are designed to be fit-tested and are not designed for public use. 

 

This means that, among other things, these devices are uncomfortable to wear for extended periods of time. While this isn’t a big issue in the occupational-use situations that these devices are designed for, it quickly becomes an issue in typical daily use. 

 

For this reason, many individuals have instead turned to cloth masks and surgical masks. However, these masks have their own issues - due to their loose fit and different materials used, they tend to provide far lower protection. 

 

This has created a giant rift among masks. On one end, there are surgical masks and cloth masks that provide low levels of protection but that are comfortable. On the other end, we have respirators. These devices offer significantly more protection, but they’re incredibly uncomfortable to wear for more extended periods. 

 

Until recently, there hasn’t been a middle ground. You could either sacrifice comfort or filtration. Luckily, some new standards have been created to try and bridge this gap - namely, the ASTM F3502-21 standard. Let’s discuss what this standard entails. 


What Is ASTM F3502-21?

Infographic from MakerMask.org.

 

ASTM F3502 is a new mask standard aimed at community barrier face coverings. It was designed to provide a balance between surgical masks and respirators while combining the benefits of both. 

 

Surgical masks are designed to prevent expelled droplets from the wearer and are well-known not to perform well in sub-micron filtration. These masks are generally chosen because they provide some protection, but they’re also effortless to wear, especially compared to a respirator. 

 

The problem is that until the creation of ASTM F3502, there was no community-focused guideline dictating the requirements these devices must meet. As a result, surgical and cloth masks could vary significantly in performance, and there was no way of knowing what protection you were getting. This is where the new ASTM standard becomes essential.

 

ASTM F3502 includes two levels - one for devices with ≥ 20% filtration and one for ≥ 50% filtration devices. While both of these levels are far lower than the ≥ 95% filtration set in the N95 and KN95 standards, they greatly improve over the previous lack of standards. 

 

Filtration is only part of the ASTM F3502 standard, however. The standard also includes guidelines for breathability (and therefore, comfort), reusability and fit. Here is a list of the improvements that ASTM F3502 brings over non-tested or certified devices.

 

  1. Masks have to undergo filtration testing.
  2. Masks have to be snug-fitting.
  3. Masks have to be highly breathable. 
  4. Masks must retain filtration efficiency even after being washed.

 

While the filtration aspect is likely to get the most attention, the other three points are equally important. 

 

Surgical and cloth masks are loose-fitting devices. As mentioned, their purpose isn’t to filter incoming or inhaled particles but rather to prevent expelled respiratory droplets from exiting the device. However, the best protection is two-way filtration. This way, if there are two people, one infected and one not, two barriers prevent the susceptible individual from becoming infected. 

 

Surgical masks don’t truly provide this two-way filtration, and this means that ASTM F3502 is a big improvement. While the filtration is significantly lower than that offered by a respirator, it’s a big step up from what was previously used. 

 

The new ASTM standard also sets breathability guidelines. Measured in terms of airflow resistance, these devices must provide ≤ 15 mm H2O (level 1) and ≤ 5mm H2O (level 2). This is an important change compared to an N95 respirator with ≤ 35mm H2O airflow resistance. Typically, a more breathable device will be more comfortable and, therefore can be worn for longer. 

 

Since many of us are expected or required to wear masks for as long as eight hours at once, this comfort improvement is much-needed. This is likely to be the biggest improvement that the new standard brings for many people. 

 

Finally, ASTM F3502 certified masks must be truly reusable (if advertised as such). What we mean by this is that these masks must retain filtration efficiency even after being washed. It’s well-known that respirators lose filtration after being washed due to their heavy reliance on electrostatic filtration. However, reusable ASTM F3502 devices must be tested both before and after wash cycles. 

 

This means that you can rest assured that any certified device will maintain performance even after being cleaned. However, consult the manual before cleaning a mask, as many have different processes. 

 

Overall, the ASTM F3502 standard is an excellent improvement over the previous lack of community barrier certifications. However, this new standard is also lacking in many ways. For example, 50% filtration (or 20% at level 1) is far lower than respirators offer. Respirators also tend to provide better fit - even without fit-testing.


What are Respirators?

Respirators sit at the other end of the scale. Where the new community face barrier covering standard requires devices to provide medium filtration with high breathability, respirators are designed to provide high filtration, which inherently leads to lower breathability. These devices also require fit testing and are designed for occupational professionals.

 

Respirators can come certified under a range of standards. The most well-known standards are N95 (U.S), KN95 (China), FFP2 (EU), and P2 (Aus/NZ). However, other standards such as PFF2 (Brazil) and DS2 (Japan) are less well-known globally. 

 

You may have noticed that I excluded KF94 devices from Korea. This is because KF94 masks are designed specifically for public use. Korea's equivalent respirator is named 1st Class and is designed for occupational use. KF94, on the other hand, is unlike N95 and KN95 devices as it is designed for public use. 

 

These devices have ≥ 94% filtration (≥ 95% for N95, KN95 and DS2 devices) and easily outperform ASTM F3502 devices in this respect. They also often tend to have more secure fitting mechanisms and provide a more solid seal. The downside is that they are designed specifically for individuals who have undergone fit testing.

 

This means that a typical person can't don a respirator and expect the same performance. So while it's likely that you will receive some protection factor, these devices aren't designed for general use. This is especially true for standards such as NIOSH's N95 certifications that require no real-subject leakage testing. 

 

On top of this, these devices tend to be very uncomfortable. This is due to their less stringent breathing resistance requirements. However, this makes sense as increasing filtration often leads to a decrease in breathability and these devices are designed to provide the best protection. 

 

Now that we've defined ASTM F3502 masks and respirators, it's evident that there's a significant tradeoff. There's no perfect answer, no matter which route you decide to take. There is always a sacrifice - whether it be filtration or comfort. Or is there?


AirPop’s Approach

At AirPop, we’ve always strived to provide the best mask for our users. We’ve been certified KN95 since 2015, and since this time, we’ve continued to improve our devices. This means that we are always seeking ways to increase comfort, filtration, and fit. This meant that we already adhered to it when the ASTM F3502 standard was released.

 

We also identified a second issue - there is a massive range of respirator standards and community mask standards. For example, Spain has introduced the UNE0065:2020 Community Barrier Face Mask standard. In the U.S, the ASTM F3502-21 standard is more commonly used. 

 

Some countries require specific standards, whereas others accept a range of standards. However, in the countries that require the local standard, it’s vital to ensure that our products abide by these specifications. 

 

To solve this problem and be trusted globally, AirPop took and continues to take a unique approach in our device testing. While most mask and respirator brands are content with achieving one standard - ASTM F3502, KN95, or otherwise - we decided to set our own standard by obtaining certifications in both of these standards and more. 

 

Currently, AirPop’s Light SE mask holds the following certifications: ASTM F3502 (Level 2), UNE0065:2020 Community Barrier Mask, AFNOR SPEC S76-001, NCS-TF Community Mask, and GB2626:2019 KN95. 

 

Of most importance among these certifications are ASTM F3502 and GB2626:2019 KN95. KN95 respirators are known globally for being high-performance filtration devices equivalent in many ways to an N95 or FFP2 respirator. On the other hand, ASTM F3502 masks are explicitly designed with the community in mind - they offer lower breathability but also lower filtration. 

 

On top of this, the ASTM standard also requires that tested devices maintain their advertised breathability, filtration and fit before AND after washing for reusable devices. This is particularly important as respirators are well known for losing filtration after wash cycles due to the heavy reliance on electrostatic filtration. 

 

When you purchase an ASTM device, you can rest assured that it will last for its specified lifespan even through wash cycles. For example, in the case of our Light SE mask, > 97% filtration was retained even after ten wash cycles with a 70% alcohol wipe. This is extremely important because it shows that our devices can be disinfected and reused after.

 

Further, with an AirPop mask, you are safe wherever you travel. While mask requirements differ between regions and countries, we do our best to obtain all relevant certifications. Therefore, you can know that AirPop devices have been locally certified wherever you travel. 


The Dual-Standard Approach

This dual-standard approach shows that instead of exclusively fitting into one of these categories, AirPop’s devices excel in both. They can adhere to and surpass the stringent requirements set by the KN95 testing while maintaining the breathability and washability set out by the ASTM standard. 

 

Since both the community mask standards and respirator standards leave something to be desired, we believe in taking a more thorough approach. Not only does this show that the devices achieve the criteria set by both standards, but it also shows that they can pass stringent tests in both China and a leading U.S laboratory. This is not to mention the range of other certifications that our masks hold.

 

Currently, we believe that we are the only company following this dual-standard approach. However, we believe that neither the respirator standards nor community mask standards are perfect and wanted to show that our masks achieve the most important requirements from both certifications.

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