Craniofacial Dimensions as Determinants of the Fitted Performance of Common Face Masks (FACEFIT 2.0)

Wearing a face mask is a primary protection strategy against airborne infectious agents as well as toxic aerosols such as wildfire smoke. Despite the ubiquitous presence of masks in public life in recent years, the average person has a poor understanding of factors that influence the fitted performance of the face coverings that they wear. This problem is exacerbated by the lack of mask fit testing available to the public outside of occupational settings subject to regulation. As a result, the vast majority of the population currently wears masks with limited knowledge of their efficacy or the means to acquire it. A simple, validated method to quantitatively self-assess individual craniofacial dimensions relative to that of the general population will permit members of the public to make informed decisions about the types of mask that they wear in specific risk situations, and whether to use fit enhancements to optimize their fitted performance. In addition to limiting the morbidity associated with exposure to poor air quality, an individualized improvement in the efficacy of mask will have a multiplicative effect in the prevention of the transmission of infectious vectors.

Assignment to study groups will be done to ensure equal variation in craniofacial dimensions is equally represented in Group A. This will ensure that data on the relationship between craniofacial morphology and mask efficiency has an approximately equal samples of those with small to large faces.

Group A: Healthy, adult subjects will be recruited and screened for eligibility for the study (See inclusion and exclusion criteria)(See Recruitment section). After giving informed consent, all subjects will complete a craniometric self-assessment form. Next, cranial and facial measurements will be collected using standard anthropological techniques and 3D imaging. Subjects will then participate in a modified version of the quantitative OSHA mask fit testing. Two disposable masks, surgical/procedure and KN95, will be tested both unmodified and modified with a clip. Participants will also complete a short questionnaire.

Group B: Healthy, adult subjects will be recruited and screened for eligibility for the study (See inclusion and exclusion criteria)(See Recruitment section). After giving informed consent, all subjects will complete a craniometric assessment using standard anthropological techniques and 3D imaging. Participants will also complete a short questionnaire.

Recruitment: Subjects will be recruited from the U.S. Environmental Protection Agency Research Triangle Park Campus. Participants will be recruited in person at the cafeteria and during large gatherings (see in-person script and flyer).

STUDY SESSIONS Subjects who are not excluded from the initial screening will be scheduled for consenting at an EPA study facility. At the start of the visit, the study protocol will be outlined, and informed consent obtained to initiate enrollment into the study. There will be one session in this study. Consenting subjects will proceed immediately to the participation phase.

Consenting: There will be one (2) study consent form (form FF2.0 1 \& 2). FF2.0 1 is used for participants in Group A and FF2.02 is used for participants in Group B. These consent forms must be signed by the participant and the study team member obtaining informed consent. The subjects may ask any questions they have regarding their participation in the study at any time prior to or during their participation. For Group A, persons with child-bearing potential will be required to self-administer a pregnancy test in a private bathroom. Those who self-administer a pregnancy test will have to confirm the results on the consent form in order to proceed to the study phase.

(Groups A and B) Behavioral questionnaire: Subjects will complete a short questionnaire (Form FF2.0 3) that asks about their predisposition to wear a face mask under a variety of scenarios. This information will be used to guide public health communications during air quality emergencies.

(Group A) Assessment of self-evaluation instructions for craniofacial measurements: Subjects will use instructions presented in a self-evaluation form (Form FF2.0 3) to measure their own craniofacial dimensions using the rulers provided and a mirror. Subjects will receive no assistance with completing the self-assessment form. At intervals of approximately, 10-40 subjects, measurements obtained in the self-evaluation will be compared to the craniofacial measurements obtained by a study team member. The results of the comparison will be used to guide revisions of the instruction in the self-evaluation form in an iterative manner. The protocol will be amended accordingly to update changes to the self-evaluation instructions.

(Groups A and B) Measurements: First, the subjects height and weight will be measured using standard methods (scale and stadiometer). They will be asked to remove their shoes and empty their pockets before being weighed. Four to eight face, head, and neck features will also be measured using spreading and sliding calipers and a measuring tape. Trained personnel (wearing gloves) will palpate the subjects face and to ensure proper caliper measurements are collected. Cosmetic pencils will be used to identify landmarks on the face and neck in order assist in the measurement of craniofacial features.

(Groups A and B) 3D Imaging: Following facial measurements, a study team member will take a 3D picture of the subject's face using a camera. The image takes approximately 10 seconds to generate. We will first position the subject in from of the camera and ask them to tighten any loose hair so we can have a clear view of their ears. It is recommended that subjects wear a non-collared shirt, preferably a t-shirt. If they wear a hair style that impacts 3D imaging, we may ask that them tie their hair in a ponytail or wear a provided skull cap. They may also be asked to remove any jewelry that may interfere with 3D facial measurements.

(Group A) Lung Function Test. Participants will complete a breathing test (peak flow meter) before and after the facemask testing. Study personnel will coach the participant to take a full breath in and then blow it out as hard and fast as they can. They may be asked to do this up to five times. This test measures the volume of air they can blow out (exhale) quickly after taking a very deep breath. This is a method to measure lung function before and after the testing procedure for safety purposes. We will stop the study and not complete the mask fit testing if the participant's peak expiratory flow (as measured with the peak flow meter) is not ≥ 80.0% of their predicted value based on their age, height, and weight.

(Group A) Assessment of filtering face piece (FFP) use: The range of variability that exists in the subject population while wearing two different types of face coverings will be assessed. Masks will consist of a KN95 mask and a surgical/procedure mask. The fitted filtration efficiency of each mask will be measured using aerosolized sodium chloride particles (mean aerodynamic diameter 0.040 microns) emitted by a particle generator. During the fit testing, the concentration of aerosolized saline particles emitted by a TSI Particle Generator will be approximately 5000-30000 particles/cc of air. The temperature in the chamber will vary between 20 and 30 oC, the relative humidity will be maintained at approximately 50 %.

The subject will remain seated in the chamber and complete a modified version the Occupational Safety and Health Administration Quantitative Fit Testing Protocol (Modified Ambient Aerosol CNC Quantitative Fit Testing Protocol for Filtering Facepiece TableA-2-RESPIRATORS). The subject will then move their head from left to right, taking two breaths at each extreme for 30 seconds. This will be followed by moving the head up and down, taking two beaths at each extreme for 30 seconds. The procedure will be repeated after the addition of a clip to the ear-loops of the mask behind the neck of the subject. In total, the testing time for the 2 masks with and without clip will be approximately 6 minutes.