High Efficiency Particulate Absolute (HEPA) filters are widely used to provide clean air to facilities where micro-organisms cannot be tolerated. HEPA filters are also used to clean the air leaving certain facilities where pathogens may be present. In these situations, the facilities are routinely cleaned using disinfectant solutions and the filtration systems may be decontaminated prior to servicing. In the course of these activities the HEPA filter will be exposed to the decontamination agent with potential detrimental effects.
Commonly used agents can be divided into two broad groups:
1. Gases and vapours used in space decontamination, including
- a. formaldehyde (gas + water vapour)
- b. hydrogen peroxide (vapour)
- c. chlorine dioxide (gas + water vapour)
- a. bleach (sodium hypochlorite) solution (oxidiser)
- b. acidic/oxidising solutions including peracetic acid/hydrogen peroxide mixtures
- c. quaternary ammonium chloride solutions.
This article primarily focuses on group 1, where occasional direct application of the decontamination agent on the installed filter occurs for the purpose of decontamination prior to servicing. Where applicable, information is also provided on the effect of the routine exposure of the filters to ambient levels of vapours from group 2 cleaning solutions used on facility surfaces.
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