Start with the decision each standard answers
- AHAM AC-1 and AHAM AC-5
- For this article, AHAM AC-1 means the ANSI/AHAM standard used for room-air-cleaner CADR and particulate performance, while AHAM AC-5 means the ANSI/AHAM standard used to assess the reduction rate of key bioaerosols by portable air cleaners in an aerobiology test chamber.1,2,4
AHAM identifies itself as an accredited standards development organization whose performance standards establish common methods for testing home appliances and reporting major performance attributes. In the room-air-cleaner family, AHAM lists ANSI/AHAM AC-1-2020 for room-air-cleaner CADR and ANSI/AHAM AC-5-2023 for room-air-cleaner bioaerosols.1
The practical split is particulate versus bioaerosol evidence. AC-1 supports a clean-air delivery question for nonbiological particulate challenges, while AC-5 supports a bioaerosol reduction question that includes concentration and viability. Both can be relevant to filtration efficiency discussions, but they should not be collapsed into one generic air-cleaner claim.3,4,8
What AHAM AC-1 shows
AHAM Verifide describes CADR as the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen, and dust. A higher CADR for a listed pollutant indicates faster filtration for that pollutant under the AHAM frame, and AHAM's consumer guidance uses CADR for room-size selection.3
EPA states that it does not certify, register, recommend, or provide lists of acceptable air cleaning devices, and points readers to AHAM as one information source. EPA also notes that the AHAM air cleaner certification program is known as AC-1, which is why AC-1 evidence is often discussed as a third-party performance-verification language rather than an EPA endorsement.9
CDC's ventilation FAQ treats CADR as a clean-air input for portable HEPA air cleaners, explains that AHAM labels give smoke, dust, and pollen CADR values, and notes that the smoke CADR is the most relevant of those label values for viral particles related to respiratory diseases because the smoke particles are the smallest listed challenge.10
What AHAM AC-5 shows
AHAM's current AC-5 item page describes ANSI/AHAM AC-5-2023 as a method for assessing the reduction rate of key bioaerosols by portable air cleaners using an aerobiology test chamber. Its stated purpose is to evaluate the capability of portable household air cleaners to reduce concentration and viability of experimentally generated bioaerosols in a specified chamber.4
AHAM's publication announcement for the earlier AC-5 edition framed the method as its first air-cleaner performance standard focused on microbiological pollutants, including viruses, bacteria, and mold. That significance is different from AC-1: AC-5 is selected when the study question is bioaerosol reduction, not only particulate CADR, room sizing, or CADR-to-watt efficiency.4,5,11
For compliance planning, AC-5 does not eliminate the need to review claim language. EPA lists air purifiers, filters, and air treatment devices among regulated device examples when they claim to reduce microorganisms or purify the air, while noting that HEPA filters limited to particle-size claims and no air-purification or microorganism claims are generally outside FIFRA device regulation.8
How ASHRAE 241 uses AHAM methods
ASHRAE describes Standard 241 as establishing minimum requirements aimed at reducing disease-transmission risk through exposure to infectious aerosols in new and existing buildings and major renovations. The standard frame is therefore a building and air-system risk-mitigation frame, not a stand-alone air-cleaner certification program.6
ASHRAE Addendum a to Standard 241-2023 lists ANSI/AHAM AC-1 and ANSI/AHAM AC-5 among consensus standards permitted for determining air-cleaning effectiveness when the method fits the system and the authority having jurisdiction accepts it. The same addendum clarifies that commercial and industrial in-room air cleaners using only mechanical fibrous filters determine equivalent clean airflow rate using ANSI/AHAM AC-1 adapted for nonresidential applications with the stated chamber-size criterion.7
| Frame | What it shows | What it does not decide alone |
|---|---|---|
| ANSI/AHAM AC-1 | Portable room-air-cleaner CADR for particulate challenges such as smoke, dust, and pollen. | Bioaerosol viability, microorganism claim support, ozone safety, or installed HVAC performance. |
| ANSI/AHAM AC-5 | Bioaerosol reduction rate, concentration reduction, and viability reduction in a specified aerobiology chamber. | Particulate CADR room-size labeling, CADR-to-watt efficiency, or all public-health claim obligations. |
| ASHRAE 241 | A building and air-cleaning effectiveness framework for infectious-aerosol risk mitigation. | Product approval, EPA device compliance, or automatic acceptance of any one laboratory report. |
Scoping questions before testing
- Name the decision first: particulate CADR comparison, bioaerosol reduction, ASHRAE 241 equivalent clean airflow, EPA claim support, or engineering screening.3,4,7,8
- Define the product configuration: portable household room air cleaner, larger in-room commercial device, ducted HEPA unit, in-duct UV system, HVAC filter, or custom recirculating system.7,10
- Separate particle removal, filter efficiency, bioaerosol viability, ozone or byproduct safety, and energy-efficiency questions before writing the protocol.3,4,10,11
- Check whether marketing language reaches microorganisms, air purification, pathogen mitigation, or public-health outcomes, because those words can change the EPA device and evidence discussion.8,9