Navigating Australia’s new HVAC filter standard

Standards Australia is in the process of replacing the AS1324 filter series, with the replacement of the existing G1-G4 and F5-F9 filter classifications with the ISO 16890 series (Figure 1). While at first glance, the new filter classification method appears far more complicated to apply, the new rating system is an improvement, as it better reflects the actual filter performance, and will help to ensure adequate protection from airborne particulates for occupants of health facilities. The adoption of the ISO 16890 series does not affect the Australian HEPA filter standard (AS4260) used to filter air for surgeries and areas in the hospital with immunocompromised patients.

The rationale behind the new filter classification method is to better/more accurately define the particulates arrested by the filter. The old classification scheme, while simple, would give no estimate of particulate arrestance, and users would need to look up the standard to try to understand how effective these filters are. There is nothing intrinsically informative about an F5 filter versus an F9 filter and what a user could expect in terms of cleaning air.

The new filter classification method describes the particulate arrestance of the filter that is specified. An ISOePM2.5 65% has been tested to remove 65% of PM2.5 particulates (i.e. particles smaller than 2.5 microns). The same filter will remove a higher proportion of PM10 particulates, but a lower proportion of PM1 particulates. The selection of this particulate size range by ISO 16890 is deliberate, since these smaller 'respirable particles' (10µm or smaller) embed deep in the lungs.