Ionizer technology comes under a range of names: "ionizing air purifiers", "bi-polar ionization", "air ionizers", "ion generators" and "ionic air purifiers". Additionally, there are air purifiers called “electrostatic air purifiers" which work similarly to ionizers. Collectively, they are termed "ionizers".
Ionizers make multiple claims about how well they will clean the air in your room, kill viruses and bacteria, prevent allergy symptoms, provide “freshness,” or eliminate odors.
In the past, these claims have been considered doubtful, not least because the ions have very limited range outside of the device, and have been subject to many different analyses / studies which have failed to justify those claims.
Now, thanks to detailed testing by Boeing, at least one aspect of their performance is now clear, ionizers are ineffective against viruses, bacteria and mold.
Boeing tested 'Needle Point Bi-Polar Ionization', as that version of the technology is licenced for aircraft, and the supplier had made strong claims of between 69% and 99% eradication of a range of airborne viruses and bacteria after 60 minutes, and also 'Corona Discharge Air Ionization'.
Air Ionization Disinfection - Huntsville Laboratory Testing
The airvorne norovirus surrogate MS2 Bacteriophage showed no observable reduction over a 60 minute interval. There were no observable surface reductions in Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, and Enterobacter cloacae over a 60 minute exposure duration.
Air Ionization Disinfection – University of Arizona Laboratory Testing
"Usually a 90% reduction is desired to be confident that a product is having any significant anti-microbial effect. Under the test conditions of this study none of the viruses achieved this level of reduction."
Air Ionization Disinfection – New 787-10 Ground Testing
Escherichia coli and MS2 Bacteriophage reductions in 30-60 minutes of treatment were much lower than the desired 3 log10 (99.9%) cabin disinfection, indeed they were generally < 0.1 log10 with higher values attributed to either experimental error or high levels of ozone.
Boeing conclude that its limited testing was unable to replicate supplier results in terms of antimicrobial effectiveness and that the systems were unable to properly deliver and maintain sufficiently high ion levels in the airplane. Similarly, laboratory-based tests did not show proper rates of disinfection, even with high ion concentrations.
Dr Wyatt blogs on his lifetime's experience of Indoor Air Quality Issues.