HVAC filters are tested by third parties; no manufacturer can test their own filters. In the United States, there are specific labs to send HVAC filters to that are government regulated, and they have to test the filters under “ash-ray” standards. These standards are constantly being worked on based on the medias that are available. The HVAC filters themselves are regulated and tested, not the manufacturer. As you’re manufacturing, they’re “ash-ray” tested. For HVAC-grade filters, they have to be tested through “ash-ray” standards in addition to a DOP test. It’s the third-party that is regulated by “ash-ray” standard, not the manufacturer.
All HVAC filters are individually certified as to conformance with their target efficiency. The data from the testing is provided on a label on every filter stating test airflow, resistance to airflow and penetration (the inverse of efficiency). Originally HVAC filters were tested using dioctylphthalate, a known carcinogen, as prescribed in the original military testing standard authored to address HVAC filter performance. Today, manufacturers test each HVAC filter according to methodologies as outlined in Recommended Practices (RP) as published by the Institute of Environmental Sciences and Technologies (IEST).
Filters are challenged with particles of specific size and the penetration of each filter is so recorded. The minimum level of HVAC filter performance is an efficiency of 99.97% when tested on particles 0.3 micron in size. As technology has advanced, and the need of ultra-clean air in industries such as microelectronics and pharmaceutical has evolved, filters have become available that can provide a performance of 99.999995% efficiency on particles 0.12 micron is size. Because a HVAC manufacturer cannot be responsible for transportation of the filters to the user or handling and installation, many applications require additional in-place testing to ensure the installed integrity of the HVAC filter.