Are these masks real? Are they any good? Is it worth paying extra for the more expensive ones? Read on to find out if the N95 masks on Amazon are what they claim to be or if you'd be better off spending more money elsewhere! External Nose Clip N95 mask with nose flap the fit is not secure enough. NIOSH N95 masc NIOSH which provide 99% filtration. There are limitations, according to OSHA, NIOSH, and CDC recommendations: You may be at risk of respiratory problems if you wear a N95 mask for more than 8 hours per day for several days in a row, or for more than 40 hours in a week. Non-medical masks are cheap and easy to find in drug stores or online. Testing the mask before using it is the only way to be certain.