Method and apparatus relating to disposable filter modules for filtering air containing hazardous substances

In a system including an enclosure for containing airborne or potentially airborne biological contamination, exhaust means communicating with said enclosure for exhausting air therefrom for maintaining said enclosure under negative pressure relative to its surroundings, said exhaust means including exhaust ducting and filter means through which exhaust air flows from said enclosure, the improvement comprising said filter means including a substantially rigid integral disposable module releasably but sealingly connected between sections of said ducting for forming an airflow path therethrough, said module comprising a substantially rigid, air-tight hollow body having an inlet and an outlet defined by releasable connecting means located respectively upstream and downstream of each other relative to the direction of airflow therethrough, said hollow body having at least one filter fixedly mounted therein and sealed in said hollow body such that substantially all airflow from said inlet to said outlet passes through said at least one filter, said module being disconnectable from said ducting as an integral unit and to be removable, disposable and replaceable by another such module at the end of the useful life of said at least one filter, said system further including means for decontaminating said at least one filter prior to removal thereof from said system.