Using blowing agents other than MC is another way to reduce MC exposure. Acetone is extremely flammable, so be sure to take appropriate precautions. Keep in mind that substitutes may also present health and safety hazards to workers. Always select substitutes that reduce hazards, and always refer to the substitute's material safety data sheet to find out about any control measures and protective equipment you must use to protect workers. If engineering controls and work practices do not reduce MC exposures to an acceptable level, you must give workers supplied-air respirators.
Respirators are the least preferred method of controlling employee exposures.
Supplied-air respirators must have a clean air supply through the use of compressed air tanks containing air meeting at least the requirements for Grade D breathing air, or a breathing air type compressor with the air intake located in an area with a clean air supply. Filter cartridge respirators cannot be used because MC can pass through available cartridges leaving respirator wearers unprotected.