Design and Performance Evaluation of Face Mask Air Filtration System
Nixon, Bradley James
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This work seeks to validate a filtration facemask concept proposed by the start-up company, O2O2 ltd, to enable a functional proof of concept prototype to be physically tested and compared with conventional facemask solutions. Conventional filtration facemasks use an unreliable physical face-seal to prevent infiltration of polluted air into the mask space while the proposed facemask does not require physical sealing, instead using fans to draw air through a filter and pressurize the mask space in front of a user’s mouth and nose before venting around the mask perimeter. This method provides the user with an ‘air-citadel’ of filtered air to prevent infiltration of polluted air and is compatible with more face shapes and facial features such as facial hair. The first stage of this report details computational simulations of the proposed mask system on realistic facial geometry. This is aimed to validate the feasibility of the facemask system and detail the required fan functional requirements during steady-state breathing up to an assumed 70% exertion effort to simulate ‘moderate exercise’. The second stage details the creation, build and use of a synthetic head testing system used to physically test of a proof of concept facemask prototype. This testing system validated previous computational simulations and identified the minimum vent flows required up to an oral inhalation demand of 103 L/min. Results were used to support an ethics application for a clinical study so that a functional proof of concept prototype mask could be tested. The final stage details a clinical study involving five participants undergoing moderate exercise on an exercycle. Participants wore a functional proof of concept prototype facemask and three popular commercially available systems while a sampling method measured air-qualities within the mask space. Results of this clinical study enabled further validation of the air-citadel concept and allowed for comparisons to be made against current commercially available facemask solutions. Results of all three stages unanimously indicated that the proposed facemask system could successfully be used to protect a user from inhaling polluted air in a contaminated environment undergoing moderate exercise. The clinical study also identified competitive advantages of the prototype mask which would justify a strong business case for commercialization of the technology.