respirator filter

The instructions should tell ow often to replace the filters. If they don't, as soon as you start to smell ANY kind of odor that they should be filtering. Keep the filters in a ZipLock back when not in use and it will dramatically extend the life because they is still a slight amount of air flowing through them even when they are not in use.

it depends on how long you have it and how frequently you use it so if i were you i'd still use it even if you spray acrylics you should still use it so you should replace the filter about every few months or so

Hope this helps