How long do activated charcoal filter cartridges for safety respirators last?

[Guest guest]

Carl and Jeff,

I just wanted to ask a technical question. Last year I remember

reading about somebody who had to investgate a mold death scene that

was heavily contaminated. The mold was growing on the back of

wallpaper and the entire apartment was covered in it.

He wore protective gear, obviously, full face respirator, gloves,

tyvek suit, etc...

He used HEPA cartridges with activated charcoal cartridges in the

respirator, but the cartridges were a few weeks old.. and he got very

sick, presumably from the MVOCs.. He said he realized that the

cartridges were no longer good.. they had been used once before a few

weeks earlier..

Which sort of begs the question.. How long do activated charcoal

cartridges for professional safety equipment last once the package has

been opened?

Also, does anybody know if they can be recharged by heating or

anything like that?