Understanding Different Types of Masks
Most disposable masks share similar construction characteristics: they are composed of multiple layers of nonwoven, polypropylene-based materials. While these masks can all reduce exposure to airborne particles, they do not perform identically.
Many commonly used mask types were originally designed for different primary purposes before the COVID-19 pandemic increased focus on airborne virus protection. As a result, naming conventions and regulatory classifications often reflect historical use cases and can be confusing. In addition, certain terms are reserved by regulatory bodies for products that meet specific certification standards.
Understanding these differences helps clarify how masks are intended to function and why performance can vary between designs.
N95 Respirators
N95 respirators were originally developed for industrial worker safety and are certified by the U.S. National Institute for Occupational Safety and Health (NIOSH).
NIOSH reserves the term respirator for products that meet its certification requirements, which is why other types of masks cannot typically be marketed using that term.
The N95 standard requires respirators to filter at least 95% of specified airborne challenge particles under defined laboratory conditions. In addition to filtration performance, N95 respirators are designed to form a tight seal against the wearer’s face.
In occupational settings, proper use typically includes fit testing to ensure that air leakage around the edges of the mask is minimized. Because of this, real-world performance depends not only on filtration material, but also on how well the respirator fits the individual user.
ASTM Level 1, 2, and 3 Medical Masks
ASTM medical masks were developed for use in healthcare environments, with a primary focus on protection from fluid splashes such as blood or bodily fluids.
In the United States, these masks are regulated by the FDA as Class II medical devices and are typically cleared based on demonstrating compliance with ASTM performance standards (ASTM F2100).
ASTM levels were designed to simplify mask selection in clinical settings, primarily based on expected levels of fluid exposure. As a result, these classifications do not directly correspond to protection from airborne particles.
Terms such as surgical, medical, or procedural masks are commonly used in product descriptions. While these terms are meaningful within clinical workflows, they do not necessarily indicate how a mask performs against airborne viral particles and should not be interpreted as a direct measure of respiratory protection.
KN95, KF94, and Other International Respirators
KN95 masks are manufactured to a Chinese regulatory standard that is broadly similar in intent to the N95 standard, with a focus on high levels of particulate filtration.
Other international standards include:
KF94 (South Korea)
FFP2 / FFP3 (Europe)
While these standards share similar goals, differences exist in certification processes, testing methods, regulatory oversight, and fit expectations.
As with N95 respirators, real-world performance depends not only on filtration efficiency, but also on how well the mask seals to the wearer’s face.
Reusable Fabric Masks
Fabric masks are typically made from woven materials such as cotton or synthetic fabrics. Their performance can vary widely depending on:
fabric type
weave density
number of layers
overall design
While fabric masks can reduce the spread of respiratory droplets and provide some level of filtration, they are generally less standardized and less consistent in performance compared to regulated medical masks and respirators.
Choosing the Right Mask
There is no single “best” mask for all situations.
Mask selection depends on a combination of factors, including:
fit and facial structure
comfort and wearability over time
breathability
filtration performance
expected exposure environment
Because mask effectiveness depends on both design and behavior, the most effective mask is often the one that a person can wear consistently and correctly in the situations where reducing exposure is important.