Assessing the Real Benefits of Filtration

In this recorded technical seminar, Jeffery Siegel, Ph.D., discusses two methods of assessing filter testing in any environment, rather than a laboratory. Both use low-cost instrumentation and provide a direct assessment of air cleaning performance. Results from portable and central air cleaning systems in a variety of different environments such as classrooms, offices, and homes show the real value of filters is specific to an environment and can be used to illustrate the direct benefit of filtration.

View Dr. Siegel’s slides here: https://amped.egnyte.com/dl/60rxksuelJ

For detailed show notes, read below and use the timestamps to navigate the episode:

[0:48] A speaker introduces Dr. Jeffery Siegel. He is internationally recognized for his work and research on indoor air quality.

[2:15] Dr. Siegel presents a passage from Leviticus about what to do if there is a moisture problem in your home to show that human beings have cared about indoor air quality for as long as they have had buildings.

[4:08] Air filtration has had a much shorter history. Standard 52.2 at ASHRAE is only 25 years old. However, we know now that we should be investing in air filtration for return on investment in avoided healthcare costs.

[6:10] We know that filtration directly impacts health, as Dr. Siegel was part of a study that showed clear evidence that using filtration is effective in reducing PM concentrations.

[7:14] A study of 123 elementary schools in the Fall of 2020 in Georgia showed that schools that invested in filtration had a clear reduction in COVID-19 cases.

[10:14] Dr. Siegel argues that even though we recognize the benefit of air quality, we have not seen much action to promote filtration.

[12:00] The University of Toronto overestimated the amount of air changes they were getting in their classrooms from their filtration.

[14:24] Filters do not necessarily perform the way that we think that they should, which can lead to doubt surrounding filtration.

[17:28] In some studies, filtration makes a huge difference. In others, the difference is very small. The context matters to filter performance.

[18:27] Dr. Seigel explains that we need a way to more accurately assess how filters perform.

[20:14] Using a machine learning approach, researchers can take raw data and find all of the places where the concentration decreases.

[24:04] Dr. Seigel calls his other approach “Flip-Flop Testing.” It is a simpler way to test a cleaning strategy’s impact on air quality.

[26:00] The periods between the air cleaner and the placebo should be two hours and thirty minutes.

[28:41] The same air cleaner will perform differently in different environments.

[29:34] Dr. Seigel speaks about his ideal testing period to get an accurate median and capture some variation within a reasonable amount of time.

[30:25] Does the monitor matter? Some low-cost monitors do not perform as well at higher concentrations.

[34:50] Dr. Seigel expresses his interest in measuring byproducts.

[36:28] Dr. Seigel discusses blinded testing in which researchers will not know what filter was installed, to avoid bias.

[38:06] Dr. Seigel asks the audience to consider whether customers will understand that the same filter will perform differently in different environments.

[39:33] Dr. Seigel is conducting ongoing research on the effect of air quality on cognitive function. He found in his research that essential oil diffuser emissions affect people’s cognitive function.

[41:55] Recent literature suggests that VOCs might be very important to cognitive function independent of any effects of particles.

[42:28] Can we use filters better? Amy Li considered four control strategies for filtration.

[49:09] Dr. Siegel says it is a great time for filtration research, but experts must provide evidence that filtration works.

[49:40] In a Q&A section, one attendee asks about Dr. Seigel’s testing related to COVID-19.

[51:52] Another attendee asks about the effectiveness of ionic generators.