Hospital Air Purification: Two-Stage HEPA and Washable Metal-Foam Filtration

What is the two-stage filtration in Iodine Air Systems hospital units?

Stage 1 is a washable open-cell metal-foam pre-filter that holds back coarse dust, lint and larger particles. Stage 2 is a HEPA filter, which by the US Department of Energy definition captures at least 99.97% of particles at 0.3 µm. Activated carbon can be added as a third stage for radioiodine in nuclear medicine areas or for odors and gases.

Why add a metal-foam pre-filter in front of the HEPA filter?

The pre-filter takes the coarse dust load that would otherwise clog the HEPA filter. The HEPA filter stays cleaner for longer, so it is replaced less often and there is less filter waste. The metal-foam pre-filter itself is cleaned and reused instead of thrown away.

Does HEPA filtration capture bacteria and viruses?

Yes. The EPA notes that a HEPA filter can remove at least 99.97% of airborne particles of 0.3 µm, including bacteria and mold, and that larger and smaller particles are trapped with even higher efficiency. Airborne viruses travel mostly in droplets and aerosols larger than individual virus particles.

Do your units kill or inactivate pathogens?

No. Our hospital units remove particles from the air by physical filtration: the pathogens are captured, not killed. We describe performance as capture efficiency backed by a third-party whole-unit test, and we do not make kill or inactivation claims.

How is the metal-foam pre-filter cleaned in a hospital?

Following a written procedure: remove the pre-filter with the unit off, bag it at the unit, wear the PPE your infection-prevention policy requires, and wash and dry it in a designated area before reinstalling. Treat captured material as potentially infectious. Pre-filters from radioactive areas such as I-131 rooms are not washed; they are handled under your radiation protection program.

Has the unit been tested by a third party?

The IAS-NC500-HI-CUSTOM, fitted with a washable metal-foam pre-filter and a HEPA filter, was tested as a complete unit by the National Center of Quality Inspection and Testing on Air Purification Products (Guangzhou Institute of Microbiology Group) using the ducted air-purification device method of GB/T 18801-2022 Annex L. Particle filtration efficiency was greater than 99.99% for KCl aerosol particles of 0.3 µm and larger (report KJ2026002491, issued September 4, 2026). The report is available on request.

Can the airflow be adjusted?

Yes. The fan runs on a variable-frequency drive, so airflow can be set for each room and task, for example higher for construction containment and lower for quiet operation in occupied areas.

Is HEPA filter replacement still needed?

Yes. The pre-filter extends HEPA life but does not replace it. Replace the HEPA filter when its differential pressure reaches the set limit or at your scheduled interval, using your facility's normal PPE and bagging procedure for used HEPA filters.

Do your units help with ASHRAE 241?

ASHRAE 241 lets filtration and air cleaning count toward the equivalent clean airflow (ECAi) a room needs in infection risk management mode. We calculate the clean airflow each unit contributes to your rooms from its airflow and filter efficiency, for your design engineer to include in the 241 assessment.

Which hospital spaces are these units used in?

Nuclear medicine and I-131 therapy areas (with activated carbon), construction and renovation containment, airborne infection isolation support, emergency department and waiting areas, and other spaces where the design engineer calls for additional HEPA filtration. Permanent ventilation for each space must still meet ASHRAE 170 as adopted by your AHJ.

Can you build a custom unit for our hospital?

Yes. Through our OEM and custom manufacturing service we build units to your airflow, size, power and filtration requirements, including built-in differential pressure gauges and HEPA test ports.