No metal use is suitable for those environments where metal is not allowed. Duckbill N95 mask duckbill NIOSH approved N95 facepiece respirator you should never put on a surgical mask and then touch your face or hair. Small size small N95 you should always wear a face mask, but the length of time you can do so depends on factors such as your respiration, environmental conditions, and medical history. Should I wear a half-face respirator or an air purifying respirator? There are some very bad products on the market that claim to be N95 masks and are not. What is the effectiveness of N95 masks against COVID-19?