Aerosolised fluorescein can quantify FFP mask faceseal leakage: a cost-effective adaptation to the existing point of care fit test.

BACKGROUND: A qualitative fit test using bitter-tasting aerosols is the commonest way to determine filtering face-piece (FFP) mask leakage. This taste test is subjective and biased by placebo. We propose a cheap, quantitative modification of the taste test by measuring the amount of fluorescein stained filter paper behind the mask using image analysis. METHODS: A bitter-tasting fluorescein solution was aerosolised during mask fit tests, with filter paper placed on masks' inner surfaces. Participants reported whether they could taste bitterness to determine taste test 'pass' or 'fail' results. Filter paper photographs were digitally analysed to quantify total fluorescence (TF). RESULTS: Fifty-six healthcare professionals were fit tested; 32 (57%) 'passed' the taste test. TF between the taste test 'pass' and 'fail' groups was significantly different (p<0.001). A cut-off (TF = 5.0 × 106 units) was determined at precision (78%) and recall (84%), resulting in 5/56 participants (9%) reclassified from 'pass' to 'fail' by the fluorescein test. Seven out of 56 (12%) reclassified from 'fail' to 'pass'. CONCLUSION: Fluorescein is detectable and sensitive at identifying FFP mask leaks. These low-cost adaptations can enhance exiting fit testing to determine 'pass' and 'fail' groups, protecting those who 'passed' the taste test but have high fluorescein leak, and reassuring those who 'failed' the taste test despite having little fluorescein leak.

Management and use of filter masks in the "none-medical" population during the Covid-19 period.

SARS-CoV-2 has become a pandemic disease declared by the World Health Organization, consequently each nation has taken a series of actions managed by the government in order to prevent the spread of this dangerous virus. The most common countermeasure is the use of a mask that should cover the mouth and nose to filter the inhaled and exhaled air. Those masks are medical devices that should be handled properly; unfortunately in our study, observation of the population during the so-called "phase 2″ has very often shown an inappropriate use of any type of mask which reduces its effectiveness. The correct dissemination of adequate information on how to use the mask and the strict control by the government not only on staying on the street wearing masks but above all on how they should be worn, could have further reduced the spread of Covid-19.