Abstract
The Particulate Respirator type N95 (US National Institute of Occupational Safety and Health) is recommended for the prevention of respiratory infection by airborne microbes. Adequate fitting is required to prevent leakage, but little scientific data is available on the leakage rate. Standardization of the training technique for fitting is also necessary. This study evaluated the leakage of N95 respirators clinically available. Using the standard face model of the Japanese Industrial Standards, the leakage rate of the N95 particulate respirators was measured. Leakage test were carried out by the Roken-type Mask Fitting Tester (type MT-03, SHIBATA co. ltd.) equipped with a particle counter. Nine types of N95 particles respirator and N100 disposable particulate respirators were tested, repeated 15 times for each type of respirator. The respirators were classified into cone and a flat-folded types. Four domestic and six imported masks were investigated. The Welch t-test showed that the value of the leak rate varied significantly (F=7.9365, p<0.0001*). The results of the comparison between the production countries and the types was χ2=135.00, p<0.0001*, and the average of the domestic types was smaller than that of the imported types. In addition, i Pearson's chi-square test showed that the average for the flat-folded type was smaller than that for the cup type (χ2=135.00, p<0.0001*). Three of the products, 1870 (3M Co. Ltd.), Sakai expression high lac 350 type (Koken Ltd.), and DD01-N95 (Shigematsu Works Co. Ltd.), had lower leakage rates than the others in the experiment repeated five times. We found no significant differences between these three types.There was no difference in average leak rate or variance between these three equivalent products. This study found more leakage and less adherence with the cone type than the flat-folded type, and with imported products than domestic masks quantitatively. These results indicate that the size of masks adequately fit Japanese people. Moreover, the three products with the lowest leak rate showed no variation.
