1.1 This test method measures the removal rate of challenge chemicals and ultrafine particles by portable air cleaners. This test method also evaluates the extent that portable air cleaners generate gas and particle phase byproducts, including formaldehyde, ozone, nitrogen oxides (NOx), and ultrafine (< 300 nm) particles.
1.2 In principle, in duct air cleaners can also be tested by this method; however, the details for the installation and operation of in duct air cleaners are not included in the method at this time.
1.3 This test method is not pertinent to the efficacy of biological aerosol inactivation by air cleaning devices nor any biological induced chemistry. It is however pertinent to any chemical reaction byproducts of such systems.
1.4 This method involves placing a single portable air cleaner in a walk-in chamber. The non-reactive chamber (20 m3 to 125 m3) starts each test at 20 °C ± 1 °C and 50 % ± 5 % relative humidity. A metal (or fluoropolymer-coated) mixing fan is present in the chamber. Air is not recirculated through heating and cooling systems during the portable air cleaner operation. Standardized challenge chemicals and particles are introduced to the chamber as initial pulse injections. Challenge chemicals include ozone, formaldehyde, limonene, xylene, tetrachloroethylene, and decamethylcyclopentasiloxane (D5). Challenge particles consist of potassium chloride with a number concentration mode of between 35 nm and 75 nm diameter.
1.5 Four tests are done for each air cleaner with the chamber reset to initial temperature and relative humidity set points after each test. For the first and second tests, challenge chemicals are spiked into the chamber and concentrations are monitored over time, first with the air cleaner off (control test) and then with the air cleaner on (device test). For the third and fourth tests, challenge particles are spiked into the chamber and concentrations are monitored over time, first with the air cleaner off and then with the air cleaner on. The air cleaner’s ability to remove the challenge chemical and particles, along with byproducts from the air cleaner operation is assessed by a mass balance analysis of the test chamber concentrations with and without the air cleaner operating.
1.6 Clean air delivery rates (CADR) are calculated for the challenge chemical and particles. Ozone, formaldehyde, NOx, ions and ultrafine particle generation are also determined.
1.7 Challenge chemical concentrations are measured via either time-averaged analysis or real-time instrumentation. Challenge particle concentrations are measured using a particle sizer with the capability to count particles with a diameter of 12 nm or lower.
1.8 This method does not determine all potential byproducts produced by air cleaning devices.
1.9 The method does not address any health effects levels of any of the additive agents, challenge chemicals or particles, or reaction byproducts.
1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
Chemistry; Air Cleaners; portable; induct
With the rise of awareness of the importance of indoor air quality because of the global COVID-19 pandemic and recent forest fires, there is a growing use of a range of air cleaning technologies. The 2022 National Academies of Sciences, Engineering, and Medicine report on “Why Indoor Chemistry Matters” (https://nap.nationalacademies.org/catalog/26228/why-indoor-chemistry-matters, 2022) listed a range of indoor air research needs. One major recommendation of the report is that air cleaning “testing approaches need to be developed that consider both efficacy and byproduct formation in a representative range of real-world environments.” Specifically, the report notes that “standardized consensus test methods could enable potential certification programs for air-cleaning products and services. Such test methods could help regulators determine whether action on these products and services is warranted.”
However, currently there is minimal research and no standards that address indoor air chemistry and byproduct production associated with various air cleaning technologies. Consumers, regulatory agencies, and manufactures of air cleaning products have all called for more research and standards to level the playing field for air cleaning products.
Air cleaning standards that call for single pass evaluation of air cleaners cannot adequately address indoor air chemistry that occurs in the room as a result of air cleaner operation. Testing done in non-chamber environments cannot be adequately repeated across labs. As such, this standard tests portable air cleaners in a room sized test chamber and tracks resulting indoor chemistry over four hours. This standard is different from existing air cleaning standards in five important ways:
1. Challenge chemicals are tested at realistic indoor levels to better represent indoor chemistry in a real environment.
2. Ozone is injected at realistic indoor levels to ensure representative indoor reactions occur.
3. All challenge chemicals are injected together in a large chamber and tracked over four hours allowing time for chemistry to occur and be quantified.
4. Both chemical removal and byproduct formation are quantified.
5. Ultrafine particle formation and removal are quantified.
While experiments were performed at the National Institute of Standards and Technology (NIST) to support the protocol development and provide precision and bias data, this work is the result of a collaborative international effort of over 20 academic, governmental and industry experts working within ASTM WK81750 over a 2.5-year time frame.
The title and scope are in draft form and are under development within this