Bipolar Ionization – An Indoor Air Quality Investigation
Ellis was recently contracted to perform an investigation on the efficacy of a newly installed bipolar ionization system in a large commercial client’s administrative office facility. These systems have been around for several decades but have experienced a bit of a renaissance in the age of COVID-19. The reason? These systems are purportedly able to neutralize particulate matter (PM) even smaller than 0.1 microns (µm) – so-called ultra-fine particles (UFPs). This is a microscopic size where you guessed it, bacteria, viruses, and specifically SARS-CoV-2 (COVID-19) live.
The client had the system installed and received a subsequent installer-generated performance report that utilized a standard dust meter to chart the efficacy of the system. Standard dust meters chart dust concentrations in the PM 2.5 µm to PM 10 µm range. Immediately, Ellis saw deficiencies in the installer’s report. How could charting a reduction in PM 2.5 draw any conclusions about the system’s ability to reduce UFPs or airborne viruses? It seemed all the more troubling as reducing airborne viral concentrations and getting people back to the office was the impetus driving the client to seek out and complete the costly installation in the first place.
Ellis stepped in and proposed a more thorough indoor air quality (IAQ) investigation for the client; one that measured carbon monoxide, carbon dioxide, temperature, relative humidity, PM 2.5 & PM 10, airborne mold, UFPs, and ozone.
The system was tested on two separate mobilizations exactly one week apart – one while the system was “OFF” and a subsequent mobilization while the system was “ON.” The elapsed time in testing was hypothesized to give the system adequate time to reach optimal performance in treating the various air masses present in the complex interior of the building. In addition to the direct system performance comparisons, outdoor concentrations on the separate mobilizations were also measured.
Significant data manipulation was required to get a better understanding of what was happening during the sampling and how it may relate to the performance of the system. Specifically, varied outdoor concentrations on the separate sampling dates made it difficult to draw conclusions on the system’s ability to reduce PM 2.5, PM 10, UFPs, and airborne mold concentrations. Outdoor levels of these constituents measured significantly higher on the date that the bipolar ionization system was in operation... indoor concentrations, unsurprisingly, were also higher. Ultimately, Ellis had to rely on ratios to attempt to compare the system’s efficacy. In this way, system performance was able to be measured as a function of the relative reduction in outdoor contaminant levels rather than total measured indoor levels on varied sampling dates.
The comparison between constituent ratios revealed that indoor, fine dust concentrations were slightly, proportionally lower while the ionizer system was in operation. Better still, there was no significant increase in ozone levels, a potentially harmful byproduct produced by some ionizer systems. In English? The system seemed to work... at least marginally, but perhaps not in proportion to its price tag
Ryan Davidson, Senior Project Manager
Ellis Environmental Management, Inc.