Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
ISO 29464:2024 — Cleaning of Air and Other Gases — Unified Vocabulary for Air Filtration
The definitive terminology standard for particulate filters, gas-phase air cleaners, and UVC devices
The Role of ISO 29464 in the Air Filtration Industry
ISO 29464:2024 serves as the master vocabulary reference for the entire air cleaning industry, consolidating terminology across particulate filters, gas-phase air cleaners, electrostatic precipitators, UVC germicidal devices, and stand-alone electrically-powered air cleaners. As the third edition of this standard (superseding ISO 29464:2017), it reflects the rapid expansion of air cleaning technologies — particularly in the wake of global awareness around indoor air quality and airborne pathogen control.
The standard is organised into seven major clause groups: general air cleaner terms, particulate matter filter terms (including EPA/HEPA/ULPA), terms related to gas-phase air cleaners (GPAC), UVC device terminology, and definitions for stand-alone electrically-powered air cleaners. This comprehensive structure makes it an indispensable reference for manufacturers, testing laboratories, specifiers, and regulatory bodies.
With over 300 defined terms, ISO 29464 is the single most important reference document for anyone writing specifications, test protocols, or compliance documentation for air cleaning equipment.
Key Terminology Clusters
| Term Category | Example Terms | Application Domain |
|---|---|---|
| General & performance | Removal efficiency, penetration, arrestance, dust holding capacity, face velocity | All air cleaners |
| Particulate filter | HEPA, ULPA, EPA, MPPS, filter class, pocket filter, pleated filter, charged filter | HVAC, cleanrooms, nuclear |
| Gas-phase (GPAC) | Adsorption, chemisorption, catalytic oxidation, breakthrough capacity, single-pass efficiency | Industrial hygiene, indoor air quality |
| UVC devices | UV-C dose, germicidal effectiveness, irradiance, residence time, photoreactivation | Healthcare, bio-safety |
| Stand-alone cleaners | CADR, clean air delivery rate, robotic air cleaner, fresh-air air cleaner, combination product | Residential, commercial |
The 2024 edition adds a completely new clause (3.7) covering stand-alone electrically-powered air cleaners, reflecting the booming market for portable air purifiers and the need for standardised performance terminology.
Engineering Significance of Standardised Terminology
From an engineering perspective, precise terminology is not merely a convenience — it is a prerequisite for reproducible testing and meaningful cross-comparison of products. Consider the distinction between “arrestance” (gravimetric, mass-based) and “removal efficiency” (particle-count-based): using the wrong term can lead to orders-of-magnitude differences in reported performance.
Similarly, the standard carefully distinguishes “filter” (media-based separation, air must pass through it) from “air cleaner” (any contaminant reduction method including electrostatic precipitation, UV, or photocatalytic oxidation). This distinction has profound implications for test protocol selection and regulatory classification.
The term “HEPA” is frequently misused in marketing. ISO 29464 clearly defines HEPA as meeting filter classes ISO 35 H to ISO 45 H per ISO 29463-1 — a minimum efficiency of 99.95 % at MPPS. Any claim not meeting this threshold is not true HEPA.
Practical Applications for Engineers and Specifiers
For HVAC engineers designing ventilation systems for hospitals, laboratories, or cleanrooms, ISO 29464 provides the precise language needed to specify filter performance unambiguously. Key terms such as “design flow rate”, “nominal filter face area”, “medium velocity”, and “resistance to air flow” form the foundation of any filter specification document.
For manufacturers developing new air cleaning products, the vocabulary standard ensures that published performance data uses recognised terminology, facilitating market access and regulatory acceptance across different jurisdictions.
Frequently Asked Questions
Q: Is ISO 29464 a test method standard or just a glossary?
A: ISO 29464 is exclusively a vocabulary standard — it defines terms but does not prescribe how to test or classify filters. Test methods are covered by other standards such as ISO 29463 (HEPA/ULPA) and ISO 16890 (general ventilation filters).
A: ISO 29464 is exclusively a vocabulary standard — it defines terms but does not prescribe how to test or classify filters. Test methods are covered by other standards such as ISO 29463 (HEPA/ULPA) and ISO 16890 (general ventilation filters).
Q: What changed in the 2024 edition compared to 2017?
A: The third edition added Clause 3.7 on stand-alone electrically-powered air cleaners, expanded the gas-phase air cleaner (GPAC) terminology, and added UVC device definitions to reflect the growing importance of germicidal air treatment technologies.
A: The third edition added Clause 3.7 on stand-alone electrically-powered air cleaners, expanded the gas-phase air cleaner (GPAC) terminology, and added UVC device definitions to reflect the growing importance of germicidal air treatment technologies.
Q: Does ISO 29464 cover cabin air filters for vehicles?
A: No — cabin filters for road vehicles and air inlet filters for mobile internal combustion engines are explicitly excluded. These are covered by separate standards and separate terminology frameworks.
A: No — cabin filters for road vehicles and air inlet filters for mobile internal combustion engines are explicitly excluded. These are covered by separate standards and separate terminology frameworks.
Q: How can a specifier use this standard effectively?
A: Use ISO 29464 as the authoritative reference when writing procurement specifications to ensure that all parties share a common understanding of terms like “efficiency”, “penetration”, “dust holding capacity”, and “filter class”. Reference the standard number in your specification documents.
A: Use ISO 29464 as the authoritative reference when writing procurement specifications to ensure that all parties share a common understanding of terms like “efficiency”, “penetration”, “dust holding capacity”, and “filter class”. Reference the standard number in your specification documents.
