Prior to Y2K gas masks were a CRAZE! The 15$ ones going for $80 and then $200+ as it got near, etc...

I just use the 3M ones that take the 2091 filters, and then the other filters if you are around chemicals. These work way better than the disposable ones when working around welding dust, drywall dust, etc, etc... They are not full face shields but I don't have a reason for one of them