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Do "Ion generators" work for TB air disinfection?

By Edward Nardell, MD Moderator | 27 Jul, 2015

Just today, Paul Jensen and I were asked to comment on whether the Samsung Ion Generator works and whether a "donation" of 60 of these devices was a good idea, and if so, where they should be deployed.

Here is the company website:

Here is a sample of what the company says on the above site:
"Samsung Virus Doctor eliminates harmful viruses which cause of serious airborne diseases such as Influenza A, subtype H1N1 and even SARS. Many academic research organisations have proven the superior effectiveness up to 99.9% of S-plasma ion. Now you can feel perfectly safe about invisible tiny enemies in the air."

I would like to see this "evidence" as I doubt that good evidence exists, especially in clinical settings. Ion generators have been around a long time. Negatively charged ions can slowly reduce "dust" in clean room settings, but the rate of decline is far to slow to be relevant to airborne infection control. As you know, WHO recommends 6 - 12 ACH ventilation. We recently published data generated in a real hospital showing that upper room UVGI with low velocity ceiling fans can, properly applied, produce 24 equivalent ACH, or "EqACH". In our experience room air cleaners (filtration or UV) often produce less than 1 Eq ACH due to low flow rates compounded by "short-circuiting" of just filtered air back into the machine. I suspect that even under ideal test room conditions that negatively charged ions can "precipitate" airborne particles at even lower rates, well under 1 Eq ACH, and useless from an airborne infection control perspective.

I start this discussion in response to the outrageous claims that industry is willing to make to sell products, regardless of the harm that can be done in terms of false assurance and diversion from effective interventions.

Testing interventions against TB transmission is extremely difficult. The end point of interest is preventing TB infection and disease, but clinical trials have been very, vary hard to do since natural transmission is variable and hard to measure. Nevertheless, it has been done for such interventions as the use of masks on patients and the efficacy of upper room UVGI. It is not good enough to show that bacteria or viruses do not pass through a room air cleaner filter, for example. The question is, under real world conditions, how many Eq ACH are produced? Maybe with enough time negative ions can kill viruses in a test chamber - no claims are made for TB - but under real world conditions - how many Eq ACH are produced? If Samsung or "academic research organizations" have the data and are willing to describe the details of the studies, then let us see it. If not, this technology should be ignored.



Edward Nardell, MD Moderator Replied at 3:20 PM, 27 Jul 2015

Self correction. I had totally forgotten that Rod Escombe had indeed
tested a negative ion generator as well as UVGI against human to GP
transmission. The devices were very high output ion generators - much
moreso than the small devices advertised by Samsung.

The article: Upper-Room Ultraviolet Light and Negative Air Ionization to
Prevent Tuberculosis Transmission A. Roderick Escombe1,2,3*, David A. J.
Moore1,2,3,4,5, Robert H. Gilman3,4,5, Marcos Navincopa6,7, Eduardo Ticona6
, Bailey Mitchell8 , Catherine Noakes9 , Carlos Martı´nez5 , Patricia
Sheen4 , Rocio Ramirez7 , Willi Quino4 , Armando Gonzalez7 , Jon S.
Friedland1,2, Carlton A. Evans1,2,3,4,5

The paper reported that UVGI was about 70% effective and that his negative
ion generator was about 60% effective - so not bad, and much better than I
suggested. There are some important caveats, however. The high capacity
negative ion generator used directly in the guinea pig chamber, not the
patient rooms, is described here:

Negative Air Ionization: "Electrostatic space charge systems (ESCSs;
prototype largescale negative ionizers [Figure 1C] [22,23]) were selected
due to their high negative ion generation rate following testing and
comparison with 24 commercially available negative ionizers, all of which
performed poorly (unpublished data). Three ESCS ionizer units were
ceiling-mounted inside the third animal enclosure and functioned
continuously. Negative ion concentration was monitored indirectly using a
charge-decay meter (IPA-287; Monroe Electronics). Ozone levels were
monitored (Aeroqual500; Ozone Solutions)."

A photo shows the large device with this caption: "An ESCS ionizer
suspended from the ceiling is shown. Approximately -25,000 V were delivered
to ;200 needle tips, where negative ions are generated in adjacent air due
to corona discharge. The current was limited to ,1 mA to ensure personal
safety. Three ESCS ionizers were sited in the Ionizer animal enclosure."

In the discussion:
"A disadvantage to negative air ionization is the accumulation of
potentially infectious particles onto adjacent surfaces or grounded parts
of the ionizer itself, as suggested by the localized outbreak of
TB-infected animals following ionizer cleaning. The walls of the ionizer
exposure chamber quickly became discoloured, the ‘‘black-wall effect’’ seen
with some commercially available ionizers. These problems may be mitigated
using localized grounded collecting plates. Another potential disadvantage
of ionizers is static charge interference with medical equipment, although
they have been used for several years in an intensive care unit without
reported problems [48]. The static charge effect on instrumentation is
minimal beyond 1 m from the ionizer. The prototype ESCS ionizer used in
this study has been shown to require careful handling and cleaning, and is
therefore not yet appropriate for clinical use, particularly in
low-resource settings. However, improved ESCS ionizers with increased range
and effectiveness, and fewer needles to facilitate easier cleaning have
already been developed and commercialized for agricultural applications,
and these devices warrant further study. Approximate ESCS ionizer costs are
US$600 for an isolation room, US$300 for subsequent rooms, and the
intrinsically simple components facilitate the potential for inexpensive

I look forward to Paul's comments on the technology. My apologies for
suggesting that there have been no appropriate field trials - this is one -
and very informative at that. It suggests that ion generators can work if
properly applied, but the massive system used was not practical due to
size and complexity of the equipment, due to accumulation of still
infectious particles on the surface, the wall blackening effects, and the
fact that UVGI was more effective with fewer problems. To compare this to
the Samsung system would require some knowledge of the relative ion
generation rate from these small devices compared to the 25,000 volt system
tested by Escombe and colleagues.

Again, apologies on my memory lapse on the Escombe study. The fact remains
that UVGI technology is now well-defined in terms of application guidelines
- dosing for rooms, etc. I submit that we have much less information on
how to dose an ion generator to know how effective this small 191 x 120 x
65 mm device compared to massive system Escombe used.


Hal Levin Replied at 5:07 PM, 27 Jul 2015

Negative ion Gen produces ozone.. not desirable from health perspective and
more likely quite harmful. Very bad idea. Removal rate from air but not
space as Ed correctly noted.

Like any technologies (including drugs), side effects and by-product must
be considered.

Hal Levin Replied at 4:03 AM, 25 Sep 2015

Apologies for my very late response to this late July post.
A further limitation or disadvantage of neg ion generators is the
production and emission of ozone which varies more or less
linearly with the voltage. Ozone has harmful effects on the
respiratory tract and these may actually offset some of the gains
of reduced airborne concentrations of airborne infectious agents.
Ozone will also react with many common indoor air chemicals
(including emissions from human skin) to form acidic aerosols,
formaldehyde, higher molecular weight aldehydes, and ultrafine
particles. (Weschler,
in Indoor Environments: Concentration and Chemistry. (http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0668.2000.010004269.x/abstract) Indoor
Air. Volume 10, Issue 4, pages 269–288, December 2000.
So, be careful not to look at only one effect of any technology,
but also look at the by-products and other implications of its

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