Review of international standards describing air cleaner test methods

The offer of air cleaners has increased significantly since the SARS-CoV-2 pandemic. However, it is not clear to what extent they can contribute to indoor air quality. There are multiple standards that describe test methods for air cleaners, but no consensus can be found on how to determine the performance of the air cleaners.
This paper contains a review of test methods for several types of air cleaners, (e.g. photocatalytic devices). This allows to make a holistic analysis of the existing test methods, in order to make recommendations for legislation regarding test methods to be used on the Belgian market.
For this paper, a literature study has been conducted to investigate the similarities and differences between several standards. The investigated documents include, among others, a French standard, ISO standards, ASHRAE standards and AHAM standards.
The literature study results in a structured overview of similarities, knowledge gaps and challenges. The main differences between the standards concern the test apparatus and the pollutants used. Most of the test methods use either a test duct, which measures the single-pass efficiency, or a test chamber, where the decay of the pollutants is measured over a certain period of time. All standards define different pollutants in different concentrations that should be tested. The test pollutants consist of VOCs, aerosols, (synthetic) dust, (acid) gases and microorganisms.
They also differ in the type of air cleaners being tested. Several test methods are suited for any type of air cleaner. Other methods can only be used for a specific type of air cleaner, e.g., UV-C lights. In this case the test pollutants, measurements and test apparatus are adapted to the specific kind of air cleaner.
Most standards lack a non-targeted analysis of the treated air, because this is too complicated or expensive to test. However, the by-products can be harmful and are relevant to test.
Overall, the test methods are not suitable to predict the air quality in a room where the air cleaner may be used. They provide a means to compare the performances of different air cleaners to each other, but they do not predict real life performance. Furthermore, most of the test methods do not test the long-term performance of the air cleaners. This is because the test methods are kept as short as possible to reduce the costs.