Quantitative fit test was performed using the PortaCount Plus (TSI Inc., St. Paul, MN). (a) Cup type which is preformed to cup shape (3M 1860 or 3M 1860S (small sized)). (b) Fold type which is flexible and free-folded (3M 1870). (c) Valve type which is similar to the fold type with the valve reducing the exhalation resistance (3M 9332). (d) One sampling tube was connected to the respirator and the other sampling tube was exposed to the atmosphere.