Assessment of Cloth Face Coverings as Source Control Under Laboratory and Simulated Field Conditions

Overview

Cloth masks have been evaluated as a potential substitute for personal protective equipment (PPE) and found lacking. Prior to the COVID-19 outbreak, the use of cloth masks was limited and the focus of the limited research available was on the filtration of various fabrics in comparison to either surgical masks or N95 respirators. The Centers for Disease Control and Prevention (CDC) guidance for the coronavirus (COVID-19) outbreak makes it clear that cloth masks are not to be considered as PPE for healthcare workers and should be used in the healthcare setting only as a last resort when no other masks or respirators are available. While cloth masks are not recommended to be used as PPE, the use of cloth masks as primary source control has not yet been examined.

This study will recruit children ages 6-11 and adults ages 18-65 living in the Atlanta/Metro-Atlanta area. Participants will be randomly assigned to wear one of four different masks. These masks are created by combining one of two different kinds of fabric (flannel or twill) and one of two attachment devices (elastic ear loops or fabric ties). Additionally, adult participants will be randomly assigned to wear the mask while walking on a treadmill at either 1.5 mph or 3.0 mph. While wearing each mask, participants will perform the following sequence of activities: In a normal standing position, participants will 1) breathe normally (without talking), 2) breathe slowly and deeply, taking caution so as not to hyperventilate, 3) slowly turn his/her head from side to side between the extreme positions on each side, 4) slowly move his/her head up and down, inhaling in the up position (i.e., when looking toward the ceiling), 5) count up from 0-20 loudly and slowly, 6) grimace by smiling or frowning, 7) bend at the waist as if he/she were to touch his/her toes, and 8) breathe normally (without talking). Each activity will be performed for 1 minute, except for the grimace exercise, which will be performed for 15 seconds. During the first two activities, the researcher will hold a mirror at each edge of the mask (nose, cheeks, and chin) to monitor whether there is fogging on the mirror. For the rest of the exercises, the researchers will note whether the mask lost its fit (e.g., slipping off the nose or face). Between activities, participants will be told to re-adjust the mask. In the second phase of research activities, participants will walk on a treadmill while wearing their randomly assigned mask. Adult participants will be assigned to a specific speed on the treadmill with no incline, either 1.5 mph, the 'light' activity level, or 3 mph, the 'moderate' activity level. Child participants will only walk at 1.5 mph. Participants will walk on the treadmill for 10 minutes. Prior to the treadmill activity, the researcher will clip a probe to the participant's ear lobe that will measure transcutaneous carbon dioxide (CO2) (i.e., non-invasively) and pulse rate continuously during the performance of all physical activities. Prior to the treadmill activity, participants will rate the comfort of the mask. Near the end of the activity, participants will their perceived exertion and again rate the comfort of the mask. During the activity, participants will be free to adjust their masks as often as needed to maintain comfort and fit. The researcher will tally the frequency at which each participant adjusts their mask and the number of times that the mask lost its fit (e.g., slipping off the nose or face) and was not adjusted. Participants will complete a post-experiment questionnaire following all activities.