ABSTRACT
Surgical and community face masks are used worldwide to reduce the transmission of respiratory infections in indoor environments. Performance parameters for these loose-fitting devices are mainly focused on material filtering efficiency, while, differently from face respirators, there are no standard methods for measuring the fraction of air leaking at the face seal. This study quantifies the total filtration efficiency (TFE), a parameter based both on filter efficiency and air leakage, of 50 face mask models with the aim of understanding the role of several mask design features on TFE performance. An instrumented head form equipped with sensors for measuring volumetric airflow and differential pressure was used to simulate the air exhalation from the mouth of a person wearing a face mask. A response surface method (RSM) was used to model the TFE experimental data. Results showed that TFE values ranged over a wide interval (from 5% to 73%), with better values at higher flow rates. A significant positive correlation was found between TFE and filter breathability. The presence of a nosepiece (NP) showed to increase the TFE on average from 4% to 6%, according to the flow rate. Significant improvements were associated only to nosepieces incorporating a metallic wire. The RSM model evidenced that the increase in the number of the filter layers and the use of a meltblown layer result in higher TFE only when a nosepiece is in place. Differently, the benefit of the nosepiece is less marked for masks made of highly breathable filters. To improve overall mask performance, the design of loose-fitting face masks should carefully compromise between breathability and filtration efficiency of the filter materials. The addition of a metallic nosepiece helps improving the TFE by limiting the air leaking at the face seal. © 1963-2012 IEEE.
ABSTRACT
Face masks are used worldwide to reduce COVID-19 transmission in indoor environments. Differently from face respirators, there are no standards methods for measuring the fraction of air leaking at the face seal of loose-fitting masks such as medical and community masks. This study applies a recently developed method to quantify air leakage at the face seal to 14 medical and community mask models with the aim to understand the role of mask design and filter properties in air leakage. An instrumented head-form equipped with sensors for measuring volumetric airflow and differential pressure was used to simulate the air exhalation from the mouth of a person wearing a face mask. Results showed that the fraction of leaking air at the face seal is not negligible and can range from 10% to 95% according to mask model. The higher the exhaled airflow rate and the lower the amount of leaking fraction. A strong correlation was found between leaking fraction and filter breathability, indicating that a better breathability can lower air leakage. Highly breathable filtering materials should be employed in the production of medical and community face masks to maximize user comfort and minimize the fraction of exhaled air leaking unfiltered at the face seal. © 2022 IEEE.
ABSTRACT
Background-Aim: A potential link has been investigated between hyposmia after COVID-19 and an increased risk to develop neurological long-term sequelae also in patients who experienced mild or moderate disease. Hyposmia is a common feature PD and parkinsonism has been reported after COVID-19 suggesting a potential link between SARS-CoV2 infection and PD. [18F]FDG PET may represent a suitable tool to capture potential common metabolic signature of hyposmia after COVID-19 and in PD patients. We aimed to evaluate brain metabolic correlates of isolated persistent hyposmia after mild-to-moderate COVID-19 and to compare them with metabolic signature of hyposmia in drug-naive PD patients. Methods: Forty-four patients who experienced hyposmia after SARSCOV2 infection underwent brain [18F]FDG-PET in the first 6 months after recovery. Olfaction was assessed by means of the 16-item ''Sniffin-Sticks'' test and patients were classified as with or without persistent hyposmia (COVID-hyposmia and COVID-no-hyposmia respectively). Brain [18F]FDG-PET of post-COVID subgroups were compared in SPM12. COVID-hyposmia patients were also compared with eighty-two drug-naïve PD patients with hyposmia. Multiple-regression- analysis was used to identify correlations between olfactory test-scores and brain metabolism in patients' subgroups. Results: COVID-hyposmia patients (n = 21) exhibited significant hypometabolism in bilateral gyrus rectus and orbitofrontal cortex with respect to COVID-non-hyposmia (n = 23) (p<0.002) and in middle and superior temporal gyri, medial/middle frontal gyri and right insula with respect to PD-hyposmia (p<0.012). With respect to COVIDhyposmia, PD-hyposmia patients showed hypometabolism in inferior/ middle occipital gyri and cuneus bilaterally. Olfactory test-scores were directly correlated with metabolism in bilateral rectus and medial frontal gyri and in right middle temporal and anterior-cingulate gyri in COVID-hyposmia patients (p<0.006) and with bilateral cuneus/precuneus and left lateral occipital-cortex in PD-hyposmia patients (p<0.004). Conclusions: Metabolic signature of persistent hyposmia after COVID-19 encompasses cortical regions involved in olfactory perception and does not overlap metabolic correlates of hyposmia in PD. An impairment in olfactory judgement seem to underlie hyposmia in PD patients while a more restricted perception deficit seems to explain hyposmia in COVID-19. The potential long term neurological sequelae of COVID-19 are of interest from the clinical and economical point of view. Studies targeting symptoms common to COVID-19 and chronic neurological diseases and aiming to explore potential common pathways are of interest also to avoid unjustified claims about a future high incidence of neurodegenerative diseases secondary to the SARS-CoV-2 pandemic.
ABSTRACT
Objective. Neuromuscular diseases (NMD) may represent a risk factor causing a more severe course and outcome of SARS-CoV-2 infection. Interestingly, we observed several cases of SARS-CoV-2 infection in Ligurian patients affected by Myasthenia Gravis from March 2020 to April 2021. Methods. We collected data from 13 patients affected by Myasthenia Gravis, followed in different Ligurian hospitals. While eight patients had a mild course of SARS-CoV-2 infection, 5 patients had an unfavorable course causing the death of 4 patients and a prolonged life threating hospitalization in one patient. We analyzed their MGFA class at the moment of the infection, the maximum MGFA class reached during their clinical history, and the previous number of myasthenic crisis. We also evaluated the age at the infection, the BMI and the number of comorbidities as independent risk factors for infection severity. Results. As expected, age and elevated BMI are independent risk factors for poor outcome of Covid-19 in myasthenic patients (mean age 68,3 range 47-87 years;comorbidity rate overall 53.8%). Also having 1 or more comorbidities predicts a higher hospitalization rate (7/8 patients, 85.7%). Interestingly, the five patients with an unfavorable SARS-CoV-2 infection course had a moderate MGFA class at the moment of the infection, but almost all (80%) had previous myasthenic crisis and the average maximum MGFA class reached during the clinical history was significantly higher (MGFA = 4), compared with the group with a prompt recover (MGFA = 2);p : 0.01. Conclusions. Among our neuromuscular patients, SARS-CoV-2 infection had a significant impact in particular in myasthenic patients causing the death of four of them and a long hospitalization in one. Despite Myasthenia was well compensated at the moment of the infection, patients with previous myasthenic crisis and a higher MGFA maximum tended to have an unfavorable course. This correlation, already described in a large French study (Solé G et al. Impact of Coronavirus Disease 2019 in a French Cohort of Myasthenia Gravis. Neurology 2021) supports the hypothesis that autoimmune neurological diseases may be a risk factor for a severe course of SARS-Cov-2 infection.
ABSTRACT
Six Italian non-accredited laboratories participated to an interlaboratory study aimed at measuring Differential Pressure (DP) and Bacterial Filtration Efficiency (BFE) of three face-mask models using methods in-line with EN 14683 standard. Methodological non-conformities were annotated. Repeatability and reproducibility on quintuplicate samples were calculated according to ISO 5725-2. Sample stability was also assessed. Laboratories were ranked according to the total standard deviation over all samples and proficiency was evaluated using z-score according to ISO 13528. Although some non-conformities were present, performances for the DP measurements were always acceptable. One laboratory had to revise the bacterial suspension preparation for the BFE test. Overall, non-accredited laboratories working during pandemic emergency performed satisfactorily. Sample-to-sample variability impacted measurement repeatability. BFE values above 98% showed good repeatability (≤1.0%) and reproducibility (≤6.1%), but high BFE uncertainty was associated to community masks. Our findings suggest that relevant face-mask conformity standards should consider uncertainty of BFE and DP measurements. © 2021 The Authors