CPAP device filter replacement is very important because it will affect not only the functioning of the CPAP device but also the respiratory health of the user. One needs to replace the air filter of the CPAP machine on a periodic basis. The non-disposable ones are recommended to be replaced within every six months. But if one is living in a dusty environment, the filter should be replaced more often, sometimes even within two weeks. The non-disposable foam filter is advised to be cleaned at least once a month.