for situations where the atmospheric level may exceed the level for which an air-purifying respirator is effective,
use a positive-pressure air-supplying respirator
for emergency response or for situations where the atmospheric level is unknown
use an approved positive-pressure self-contained breathing apparatus or positive-pressure air line with auxiliary self-contained air supply
in confined or poorly ventilated areas ,
use an approved self-contained breathing apparatus or positive pressure air line with auxiliary self-contained air supply
the following should be effective types of air-purifying respirator : Organic vapor cartridge with a particulate pre-filter