INFECTED PEOPLE (medical or regular people) CAN SPREAD INFECTION IF USEING THESE PURGE VALVE MASK....I have been used these type mask with purge for years as professional use...YES THEY KEEP YOU COOLER INSIDE AND LESS FOGGING GLASSES..THATS IT! .....WARNING! Everytime You EXHAUST IT GOES DIRECTLY THROUGH AND POSSIBLY ON SOMEONES FACE!! YOU DONT HAVE TO BE A ROCKET SCIENTIST TO CHECK THIS OUT...Try it for yourself ...#1 If using N95 PURGE VALVE ...HOLD A HAND APPROXIMATELY 6 INCHES OUT IN FRONT AND APPROXIMATELY 4 INCHES DOWN AND GIVE A GOOD BLOW OR COUGH...There it is you just EXHALED ON SOMEONE.....THESE PURGE VALVE MASK SHOULD NOT BE USED IN STERILE TYPE Environments ESPECIALLY......NO TELLING HOW MANY PEOPLE ARE USING THESE MASK IF INFECTED AND ARE SPREADING THE VIRUS!