Quantitative fit testing of filtering face-piece respirators during the COVID-19 pandemic reveals anthropometric deficits in most respirators available in Iran

Abstract

Purpose Frontline health care workers (HCWs) must wear a standard N95 or FFP2 respirator during worldwide pandemics of respiratory diseases including COVID-19 to protect against airborne infectious pathogens when performing care activities. This study aimed to quantitatively investigate the fit of most of the common FFRs used during the COVID-19 pandemic in Iran. Methods A total of 37 volunteers were fit tested in 20 selected FFRs in a randomized order. The selected FFRs were underwent quantitative fit testing by PortaCount® model 8038. To determine the effects of face sizes on respirator fit, the participants’ facial dimensions were measured using a digital caliper. Results The rate of passing fit tests for the studied FFRs were surprisingly low with 11 out of 20 FFRs having less than 10% passing fit tests and the best performers having only 43% and 27% passing fit tests (brands 2 and 20, respectively). Cup-shaped respirators provided significantly greater fit than the vertical flat-fold ones ( p < 0.001). A significantly different FFs were found among the respirator brands (F = 13.60, p < 0.001). Conclusion Overall, unacceptably low fit factors were obtained from the studied FFRs. The main reasons for this are suspected to single size and style for each studied FFR. It confirms the importance and requirement of the proper respirator selection in that way fitted optimally into facial dimensions, appropriate usage, and properly performing the fit testing procedure. A unique fit test panel should be developed to guide respirator wearers in selecting the appropriate FFR for their specific face sizes.

Evaluating the fit-effectiveness of fabric-based reusable face masks on 3D printed NIOSH headforms

“…This finding coincides with another research team's work in which the majority (less than 10%) of respirator face masks did not properly fit a variety of head shapes. 9 Further, these findings echo what has been stated multiple times in the literature -most face masks do not fit properly. 5,7,10 The fit of the various face masks on each of the five NIOSH 15 headforms was also examined in this research.…”

“…To the authors' knowledge, no tool has been published in the literature to assess the quantitative fit of face masks at key areas of the face. As previously mentioned, many authors 1,6,7,9 simply stated that face masks must properly fit and measure particles within and outside the mask to validate the fit. This method of fit assessment does not coincide with traditional methods developed in the field of apparel design, and does not provide a true method for evaluating how the face mask sits at various locations of the face.…”

“…10 Other researchers have pointed out the need for an ethnically diverse pool of fit models when determining the best face masks to fit certain populations. For instance, Fakherpour et al 9 stated that most face masks on the market were not specific to the facial geometries of Iranians (their subject pool), and this may have affected the overall goodness of fit for the masks. Thus, for the present study, 3D printed headforms were created of the five established head shapes created by NIOSH.…”

“…6,7 Other research teams had face mask-wearing participants conduct exercises, such as breathing, moving the head, and bending down at the torso, before testing the particles. 1,9 This method allows for a calculation of how many particles escape the face mask; large differences in concentration imply small gaps and leakage. O'Kelly et al 7 claimed their calculation was a reliable method to validate the fit of the face mask.…”

“…10 Another team of researchers used digital calipers to group their 37 participants into size ranges based on head dimensions. 9 This team utilized male and female participants in their sample and categorized participants into three sizes of heads: small, medium, and large. They tested face mask fit quantitatively by checking particles inside and outside the masks on the various head sizes of their participants and found that most of the respirator-style face masks tested did not fit well.…”