The New Silicone N99 Half-Piece Respirator
Condition: COVID; Personal Protective Equipment
Study type: Interventional

Summary: 
      Filter facepiece respirator (FFR) is a critical equipment to prevent the transmission of
      respiratory tract infection disease especially the dreadful corona virus 2(SARs-CoV-2).The
      N95 mask is the prototype of high efficiency protective device and can effectively protect
      airborne pathogens of less than 0.3 μm by more than 95%. It is tightly fit and had high
      filtration capacity. The widespread pandemic of COVID-19 leads to greater requirement of FFR.
      A rising in demand would greatly exceed current productive capabilities and stockpiles and
      would almost certainly result in a robust shortage.

      In order to solve these problems, our team had invented a new type of half-piece respirator
      made from silicone and assembled with hepa or elastostatic filter . A variety of methods have
      been used to evaluate this new device, including qualitative fit test with Bitrex® test kit
      and filtration test.
    

Detailed description: 
      As required by Occupational Safety and Health Administration OSHA)[7], the halfpiece
      respirators need to pass the fittestto identify those individuals who do not achieve the good
      fit necessary for adequate protection. The performance of this respirator was also determined
      by measuring percent leakage under constant airflow[8]. The purposes of this study was to
      evaluate the fitting characteristicof our newly invented silicone N99 respirator and the
      performance against 30 µm particles using NaCL aerosols. The study was conducted to achieve
      two specific research objectives

        1. To investigate the fit characteristic of the novel silicone mask and whether the strap
           adjustment can help reduce the face-seal leakage

        2. To determine the level of performance by measure the inward leakage of the generated
           aerosolswith the new filter and used filter for up to 24 hours.
    

Intervention name(s): Fit test; Filtration Test
Intervention type(s): Device; Device
Intervention description(s): Bitrex Fit Test The Bitrex test uses a person's ability to test a bitter solution to determine whether a respirator fits properly[11]. Each subject was given a taste-threshold screening test prior to each fit test to ensure that he or she could taste. This process was done without subject wearing a respirator. After passing the sensitivity test, the subject will process to 7 steps of fit test as following
Breathe normally
Breathe deeply
Head side to side
Head up and down
Bent over wrist, jogging
Talking
Breath normally Each step took 60 seconds and the Bitrex solution was refilled into the hood every 30 seconds with half dosage of the amount of the previously test. We asked the participant if he / she could taste the solution during each steps of the test . The test was considered a failure, otherwise, a pass.; Respirator Performance
The real time respirator performance test method was developed using MT-05U machine (SIBATA model, Saitama, Japan), which measure particle concentrations of diameter 0.03 - 0.06 µm using and particle generator laser beam scattering particle counter that measure particles outside and inside the mask. The ratio between these two values reflected % leak as following:
leak=((Paticle inside the filter))/((Paticle inside the filter)) x 100 And calculate % filter performance = 100 - % leak We tested at the airflow rate of 40L/min which is 3-4 times higher than normal physiology, assuming that there should be no leakage through the filter. We tested 2 types of filter is CareStar and SafeStar that was incorporated with the silicone mask. CareStar is limited for 24 hour usage and SafeStar is for 72 hour duration.
Study protocol
Intervention model: Single Group Assignment
Intervention model description: N99 respirators will be tested in a group of subjects with qualitative fit test.The filters will be tested for filtration test.The results will be considered as pass or fail
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: respirators; n99; COVID-19