A Rapidly Deployable Test Suite for Respiratory Protective Devices in the COVID-19 Pandemic

Abstract

Introduction: The current COVID-19 pandemic has caused large shortages in personal protective equipment, leading to hospitals buying their supplies from alternative suppliers or even reusing single-use items. Equipment from these alternative sources first needs to be tested to ensure that they properly protect the clinicians that depend on them. This work demonstrates a test suite for protective face masks that can be realized rapidly and cost effectively, using mainly off-the-shelf as well as 3D printing components. Materials and Methods: The proposed test suite was designed and evaluated in order to assess its safety and proper functioning according to the criteria that are stated in the European standard norm EN149:2001+A1 7. These include a breathing resistance test, a CO2 build-up test, and a penetration test. Measurements were performed for a variety of commercially available protective face masks for validation. Results: The results obtained with the rapidly deployable test suite agree with conventional test methods, demonstrating that this setup can be used to assess the filtering properties of protective masks when conventional equipment is not available. Discussion: The presented test suite can serve as a starting point for the rapid deployment of more testing facilities for respiratory protective equipment. This could greatly increase the testing capacity and ultimately improve the safety of healthcare workers battling the COVID-19 pandemic.

Comparison of filtration efficiency and respiratory resistance of COVID-19 protective masks by multi-national standards

“…PFE of masks was measured using an approach based on the requirements of EN 149:2001+A1:2009 (EN 149+A1). 23 Firstly, we need to adjust the filtration efficiency detection system to the detection state, and set the related test parameters. Then connect the filter element to the detection device in an airtight manner with a suitable clamp.…”

Possible toxicity of chronic carbon dioxide exposure associated with mask use, particularly in pregnant women, children and adolescents -a scoping review

“…A project at the University of Delft used a validated method that clearly demonstrated that carbon dioxide re-breathing under standardised laboratory conditions (test suite) after 1 minute is at least 0.9% CO 2 for N95/ FFP2 masks [20]. Those elevated carbon dioxide levels of inhaled air, particularly under N95 masks, have also been found in physiologic relevant short-time modeling studies.…”

“…This is because carbon dioxide is heavier than other air components (approximately 44 g/mol in CO 2 compared to 32 g/mol in O 2 and 28 g/mol in N 2 ) and could accumulate there over time to a lesser extent than in the lower parts of the dead space of the mask [21]. In contrast, Butz provided a positioning of the sensor close to the mouth attached to the cheek [18], like Blad [20] and Sinkule [23], who placed it close to the breathing orifice (mouth opening), while Rhee and Roberge chose the nasolabial fold [25,27].…”

“…When masks are used elevated CO 2 concentrations are inhaled [18][19][20][21][22][23][24][25][26][27]. Despite the compensatory mechanisms that occur [28] an arterial PaCO 2 rise is inevitable in the long term [29].…”

“…The buildup of CO 2 behind the masks is predominantly within the short term exposure limits of NIOSH and EN149 [17,19,20,24,27], but even with values which do not go beyond this limit in the short term [20,21,27], a long-term pathological consequence with clinical relevance is to be expected [15][16][17]19,[21][22][23]27,50,51]. This is as a result of the longer lasting effect with a subliminal impact and significant shift in the pathological direction.…”