Spent about 6 hours in the shop and now I have a splitting headache again. It's been like this for quite awhile. If I'm doing something that doesn't require a respirator then no headaches. If I spend more than 4 hours in it I get this throbbing headache. Respirators a 3m, half face, dual cartridge. I use the pink 3m cartridges that have both a particulate filter and an activated charcoal filter for gas. Current ones seem to be fine a as far as not restricting air flow, seals right to my face, can't smell chemicals or anything I'm grinding or sanding while I have it on. Anyone have an experience like this or have an idea for a solution? The respirator seems to be the variable that causes it. Any help is greatly appreciated because I just tough it out but it sure makes the work less enjoyable.