When I worked as a mold remediation technician under strict negative air environments, we could expect our p100’s to last approximately 12 hours, with reduced effectiveness for 6-8 more hours.
Working in a chem suit is a ***** I might add. Legally had to take a break every 15 minutes in those suits. Very easy to freak out and rip your mask off, I have seen it happen.
Never be afraid to do the righteous thing, nothing righteous is ever easy.