From Outer Space to Terra Firma

Courtesy Photo | A new frontier for testing protective masks that safeguard warfighters from chemical and biological threat agents.
April 27, 2020

The Wearable Respirator Protection Assessment System (WRPAS) does what the previous mask-fit-evaluation device cannot do: it can test the fit of a warfighter’s protective mask while the warfighter is engaged in activities that simulate those required for military operations. WRPAS was initially designed by a commercial manufacturer for the National Institutes of Health. The Defense Threat Reduction Agency (DTRA) funded the manufacturer to modify the device to better evaluate the fit of protective masks worn by warfighters on the ground. The modification is an example of an innovative, small business technology developing into a candidate for defense acquisition. Prototypes of WRPAS are available and in field-testing with the Respiratory Protection Branch of the U.S. Army’s Combat Capabilities Development Command’s Chemical Biological Center. A version of WRPAS is also being deployed on the International Space Station to support environmental particle analysis.

The warfighter’s protective mask is the first line of defense against lung or eye exposure to chemical and biological warfare agents. For the greatest respiratory and ocular defense, the mask must correctly fit upon the warfighter’s face, meaning unfiltered air should not enter through gaps between mask and skin. To ensure that a mask fits well, all warfighters regularly have their masks fit-tested, which is a critical part of the scheduled mask-maintenance program.

Currently, the assessment of correct mask fit is verified using the M41 Protection Assessment Test System (M41 PATS). M41 PATS employs a particle counter that monitors the number of particles that are naturally present in ambient air and compares that number to the count of particles inside a protective mask (while the warfighter is wearing it). The numerical comparison results in a fit factor, which is a ratio of the outside-to-inside particles. The higher the fit factor, the better the mask fit.

Because protective masks filter the air that enters, the particle count inside a properly fitting mask should be very low compared to the number of particles in unfiltered air. However, a poorly fitting mask has gaps between the mask’s rubber gasket and the face, which allows unfiltered air to pass into the mask. The passage increases the number of particles inside the mask. While usable, M41 PATS has some weaknesses: it requires a controlled, indoor environment for testing, which means that warfighters are not performing their mask-fit tests in operationally relevant conditions; it needs alcohol to count particles, but the type of alcohol needed is not readily available in the field; and the device must be stationary during the fit test.

Unlike M41 PATS, WRPAS is a versatile device that is portable, functional in any physical orientation, and able to store and wirelessly transmit test data. WRPAS is a lightweight (about four pounds), wearable particle-counting system designed to measure the fit and integrity of a protective mask in a simulated, operational environment. The device simultaneously measures particles inside and outside of the mask, providing a continuous, real-time protection factor. WRPAS uses a water-based, particle-counting technology that is able to count particles as small as 10 nm, making it more sensitive than M41 PATS. The new device also stores and wirelessly communicates mask-fit data, which allows command teams to monitor, in real time, how well their warfighters’ faces are protected from threats. WRPAS is resistant to temperature extremes, pressure changes, and vibration fluctuations arising from movement. Also, the device operates in any orientation while the soldier is active (running, jogging, firing a weapon, etc.), which means that the data collected can inform what operational actions pose the highest risk of reducing the protection capability of a warfighter’s mask.

With WRPAS, warfighters can test the fit of their masks while performing simulated, mission-related duties. When a protective mask remains properly fitted throughout all activities, a warfighter can wear it on the battlefield with confidence, knowing that it is protecting their eyes, lung, and face from chemical and biological hazards.