The Dentec Comfort Air NxMD, shown with N95 cartridges.
The black Dentec Comfort Air Nx, shown with P100 cartridges.

The Dentec Comfort Air Nx is a reusable elastomeric respirator without an exhalation valve. The product comes in two forms: the Comfort Air Nx, designed for general purpose usage, and the Comfort Air NxMD, designed for usage in healthcare settings. The Comfort Air Nx is one of the first NIOSH-approved respirators without an exhalation valve.

The Comfort Air Nx model has a black facepiece and black N95 cartridges, while the NxMD model is white and has white N95 cartridges. Both models come in small/medium and medium/large sizes (see sizing information). Each model is available in an N95 cartridge and P100 cartridge form, and each of these configurations has been NIOSH-approved (approval # 9355, 9356).

The Dentec Comfort Air Nx is a variation of Dentec's Comfort Air 400 (valved) series. In addition to the exhalation valve-free facepiece, the Comfort Air Nx (95 cartridge version) features N95 cartridges that were designed to decrease breathing resistance, increase audibility of the wearer, and make a user seal check — in lieu of exhalation valve — easier. The N95 cartridges have a dome-like design and have a smaller area to seal (during seal check) versus their N95 cartridges for their valved respirators.

Unlike some of the other (2021) exhalation valve-free NIOSH-approved respirators, the Comfort Air Nx does not even appear to have an exhalation valve. Other NIOSH-approved exhalation valve-free respirators, such as the GVS Elipse P100, use the same facepiece design as their valved version with an internal valve plug. According to Dentec founder Claudio Dente, one of the reasons the white color of the Comfort Air NxMD was chosen was to make the lack of valve more obvious at a glance in a medical setting.


According to Dentec:

One trick, for those with smaller hands, for getting a faster 100% seal during a positive and negative seal check is to use two plastic ziploc bags placed over your hands.
Breathing resistance testing by NIOSH uses Millimeter Water Column (MMWC) for inhalation and exhalation resistance. Nx series respirator with N95 have 4.2 and 3.5 MMWC Inhale and exhale resistance respectively. This translates to 0.41 and 0.34 Mbar (millibar) respectively. NIOSH maximum allowable MMWC Inhalation and Exhalation resistance is 35 and 25 respectively (3.43 and 2.45 MBAR) you can see we are a fraction of maximum allowable limits. As for P100 Cartridge style filters the ComfortAir Nx Series respirators have 6.2 and 5 Inhalation and Exhalation resistance respectively. This translates to 0.60 and 0.49 MBAR.

User seal check

A positive and negative user seal check can be performed on the Comfort Air Nx as per the manufacture's instructions (using hands). The N95 cartridges are designed with a smaller opening to allow for easier hand sealing. Despite this, some users with smaller hands may find it takes some time (moving hands, adjusting fingers, etc) to obtain a 100% seal of the curved N95 filters. In this case, one trick is to use two plastic bags, placed over hands, to quickly and completely seal the filters during the check.

Quality Assurance

Proper seating of the N95 filter media in the NxMD white filter holders and covers can be verified by using backlit inspection. The filter discs must reach to the sides of the filter cartridges to be properly sealed and to prevent filter bypass. Dentec's filter replacement video shows how to disassemble the cartridges and properly seat the filter media. If adjustment is needed, be sure to re-inspect the cartridges after re-assembling them as the filter media can shift when the holder and cover are being pressed together.

Example of backlit inspection showing an improperly seated Dentec N95 filter pad possibly allowing filter bypass.


Video of Naomi Wu discussing the Dentec Comfort Air Nx.

Videos of the Comfort Air Nx being worn can be found on the Dentec YouTube channel.

See also