ASHRAE 241 Testing for Air Cleaning Systems

Under ASHRAE Standard 241, Control of Infectious Aerosols, an air cleaner’s contribution to a room’s equivalent clean airflow has to be established by testing. Airmid Healthgroup runs that testing in controlled bioaerosol chambers in Dublin and reports the reduction your system achieves against an airborne virus surrogate.

We aerosolise MS2 bacteriophage, a safe and widely used surrogate for airborne viruses, and compare your system switched on with matched runs switched off. The difference over natural decay gives the equivalent clean airflow your system delivers.

Standard

ASHRAE Standard 241-2023, Control of Infectious Aerosols

For

Air cleaning systems and technologies whose makers need independent performance data

Test organism

MS2 bacteriophage, a safe surrogate for airborne viruses

Test design

System on versus system off, with at least three replicates per condition

Sampling

Air sampled before the system starts, then at set time points (for example 5, 10, 15 and 30 minutes)

You receive

A report of the measured reduction and the equivalent clean airflow your system delivers

Laboratory

Biosafety level 2 aerobiology chambers in Dublin

Timeline

Confirmed in your quote, once we know your system and protocol

Who uses ASHRAE 241 testing

• Manufacturers of portable air purifiers and in-room air cleaners
• Developers of air cleaning technologies, including HVAC-based systems
• Building developers and regulators who need independent evidence of air cleaner performance

How it works

1. Tell us about your system. The technology, its airflow, the room size it is designed for and the claims you want to support.
2. We agree a protocol and quote. Organism, chamber conditions, sampling times and reporting are set out before testing starts.
3. We test in the chamber. After the chamber is disinfected, MS2 is aerosolised and baseline samples are taken. Your system then runs while air is sampled at set times. Control runs without the system measure natural decay.
4. You receive your report. It gives the measured reduction and the equivalent clean airflow your system delivers.

Why Airmid Healthgroup

• Involved in the standards: members of the ASHRAE 241 review process, ASHRAE 185 and the ASHRAE Environmental Health Committee, and of ISO and IEC air cleaner committees.
• Air cleaner testing specialists: we work closely with AHAM on AC-5 testing.
• Biosafety: bioaerosol testing follows the CDC/NIH Biosafety in Microbiological and Biomedical Laboratories (BMBL) guidelines.
• Trusted by patient organisations: endorsed by organisations such as the Asthma and Allergy Foundation of America (AAFA) and ECARF.
• Research-led: part of the ARPA-H BREATHE project.

Request an ASHRAE 241 test quote

Tell us about your system: the technology, its airflow, the room size you are designing for and the claims you need to support. We will come back to you to scope the test.

Prefer to talk? Call +353 1 633 6820.

Common questions

Want the full technical detail first? Read about our ASHRAE 241 testing service, or our guide to what ASHRAE Standard 241 means for air cleaners.