Independent testing of HVAC and air cleaner filters in accordance with ANSI/ASHRAE 52.2-2007 — the global benchmark for particle-size efficiency and MERV performance

What Is ANSI/ASHRAE 52.2-2007?

ANSI/ASHRAE Standard 52.2-2007 sets out the laboratory test method used worldwide to evaluate general ventilation air-cleaning devices. It measures particle size removal efficiency (PSE) across the critical 0.3 to 10 µm size range — particles that include dust, pollen, bacteria, and smoke.

The standard also introduced the Minimum Efficiency Reporting Value (MERV), a simple rating scale (1–16) that allows engineers, regulators, and purchasers to compare filter performance quickly and consistently.

By defining both the test method and the reporting system, ASHRAE 52.2 has become the cornerstone for air filter specification in residential, commercial, healthcare, and laboratory settings.

Key Concepts in the ANSI/ASHRAE 52.2-2007 Standard

• Particle Size Efficiency (PSE):

Filters are challenged with standardized aerosols, and performance is measured at multiple particle sizes across several loading stages.

• MERV Ratings:

Derived from PSE results, the MERV scale communicates how effectively a filter captures fine, medium, and large particles.

• • MERV 1–4: Large particles (>10 µm), basic residential filters.

  • MERV 5–8: Medium particles (3–10 µm), common in homes and offices.

  • MERV 9–12: Fine particles (1–3 µm), better dust and allergen control.

  • MERV 13–16: Very fine particles (0.3–1 µm), used in hospitals, labs, and clean facilities.

Addendum B: Arrestance & Dust Holding Capacity

With the 2007 update, ANSI/ASHRAE 52.2-2007 became self-contained by incorporating two key metrics:

• Arrestance – measures the percentage of large synthetic dust captured by low-efficiency filters (MERV 1–4).

• Dust Holding Capacity (DHC) – quantifies the total dust weight a filter retains over the course of a full test.

While DHC gives useful comparative data, it does not directly predict filter lifetime in the field.

Appendix J: Optional Real-World Conditioning

Appendix J describes an optional, informative test where filters are pre-conditioned with fine potassium chloride (KCl) particles rather than standard dust. This method helps simulate real-world efficiency degradation over time.

Although widely referenced, Appendix J is not part of the normative compliance pathway and remains an optional add-on.

Why ANSI/ASHRAE 52.2-2007 Matters

• Comprehensive Data: Measures efficiency across particle sizes that directly impact indoor air quality and health.

• Global Benchmark: Forms the basis of building codes, procurement standards, and certification programs worldwide.

• Practical Relevance: MERV ratings allow straightforward filter comparison without sacrificing technical rigor.

• Future-Focused: Updates like Appendix J help bridge the gap between laboratory tests and real-world performance.

Airmid’s Expertise in ASHRAE 52.2 Testing

At Airmid Healthgroup, we provide independent, ISO/IEC 17025-accredited testing for HVAC filters and air cleaning technologies in full compliance with ANSI/ASHRAE 52.2-2007 .

Our multidisciplinary team brings together aerobiology, particle science, and regulatory insight to deliver results you can trust. Whether you are a filter manufacturer, HVAC system designer, or regulatory body, Airmid ensures your products meet the highest standards of transparency and performance.

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Contact us today to learn more about ASHRAE 52.2 testing and how Airmid can help you validate performance, meet compliance requirements, and strengthen market claims.