Since the start of the COVID-19 pandemic more than 2 years ago, N95 respirator masksTrusted Source have played an important role in the personal protective equipment (PPE) of healthcare workers around the world.

A study in 1998 showed that N95 masks approved by the United States National Institute for Occupational Safety and Health (NIOSH) are capable of filtering out 95% of air particlesTrusted Source, though it did not look at viruses. However, more recent studies suggest the fit of a face maskTrusted Source determines how well a mask filters out airborne particles.

Now, a research team from Monash University in Australia says a fit-tested N95 mask combined with a portable HEPA filtration system offers the best protection against viral particles in the air.

The study was recently published in The Journal of Infectious Diseases.

What was the study’s purpose?
According to lead author Dr. Simon Joosten — respiratory and sleep medicine physician at Monash Health, senior research fellow for Medicine Monash Health at Monash University — this study had two main purposes.

The first was to “quantify the degree of personal contamination with virus aerosol when wearing different types of masks in combination with face shield, gown, and gloves.”

During this study, the research team measured the protection provided by surgical masks, N95 masksTrusted Source, and fit-tested N95 masks.

A disposable surgical mask protects the wearer from large droplets of bodily fluids. It also helps protect patients from the wearer’s respiration.

An N95 mask provides a tighter fit around the face than a surgical mask. It helps protect the wearer from breathing in small aerosol particulates in the air, such as viruses.

Because every person’s face is different, not all sizes and brands of N95 masks fit everyone the sameTrusted Source. The U.S. Occupational Safety and Health Administration (OSHA) offers a fit testing procedure where employers help their employees determine which N95 masks provide the most protection.

A fit-tested N95 mask should fit so well it ultimately provides a “seal” between the edges of the mask and the wearer’s face.

In addition to testing the different masks, Dr. Joosten told MNT, the team wanted to determine if the use of a portable HEPA filter enhances the benefit of personal protective equipment to protect the wearer against virus aerosol contamination.

A high-efficiency particulate air (HEPA) filter is capable of removing 99.97% of any air particles with a size of 0.3 microns.

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