What is inside of a p100 filter? I thought it's just paper

>>1204084
particulate filters last forever. And one of my masks has removable paper inserts. Every so often I tap the dust out of them and reuse.
charcoal/activated carbon/ have a lifetime after they are opened, but that depends on use.

>>1204133
Thanks man, you could also use a vacuum cleaner too to get even more dust out.

If the filter has activated charcoal and it's expired is it still safe to use? I know the charcoal may not be as effective but could it break down into something harmful past the expiration date or probably not?

The expiry date for filters is only the "Manufacturer won't guarantee it matches specifications after this date" notice. Most are vacuum packed from the factory, and nothing bad is going to happen to the activated charcoal over long periods of time.

Once you open the package, though, the charcoal will start absorbing things from the air and gradually drop off in filtering ability, but for most substances the simple "Can I smell paint thinner" lets you know its working (or not). Exceptions to this are isocyanate paints, where the exposure limit to them is way below the point at which you can smell them, so for these you use fresh filters and replace them regularly, after a set number of hours.

>>1204432
I see so for most nuisance level stuff expired filters are fine. For stuff that's immediately hazardous you want new filters, keep track of how long they were exposed to air and seal up after use and replace after a set number of hours.

>>1204233
Sure. The thing about that is activated carbon is there to gobble up harmful chemical vapors. The longer the carbon has been exposed to air the lower its ability to do that. I put mine in a ziplock baggie when not in use. Though the worst that gets it is bugspray for the yard, and that stuff is "supposedly" safe for not using a respirator.
For those dealing with chem-warfare levels of shit, you use a new filter every time. They come in a handy vac sealed tin can.

>>1204432
>nothing bad is going to happen to the activated charcoal over long periods of time.
No. If its stored in an airtight container it has a nearly infinite shelf life. However if you have a carbon filter rolling around the bed of your truck, it will most certainly "go bad" and lose its ability to filter.

For regular paper filters, it doesn't matter a whole lot, other than paper can slowly deteriorate when exposed to moisture such as humid air. Considering how cheap they are, treat yourself to a new set of filters regularly. Don't consider them a lifetime consumable. Especially when you're regularly exposed to harmful shit like sewer gasses, mold, and harsh chemicals.