In nature Negative Ions are created by means of wind, sunlight, surf, waterfalls and rainstorms. Generally, a negative ion is an electronically charged molecule made up of oxygen. A positive ion in the air is a molecule that has lost its electrons through process of air pollution. In fresh country air we find up to 4000 negative ions per cubic centimetre - the size of a sugar cube. Near strong surf or close to a waterfall up to 10.000 negative ions can be found, however the number of negative ions in major capital cities at rush hour does not even reach 100.
Negative ions have a powerful impact on both our lives, and the environment. It was originally found to expedite recovery in asthma and burn patients, but it was later discovered that it effects our serotonin levels in the bloodstream- stabalising alpha rhythms, and positively impacting our sensory stimuli reactions. This level of alertness can translate into improved learning, well being, and enhanced human performance on tasks that are mentally taxing.
Air that has been ionised substantially reduces the number of airborne bacteria indoors. Dr. Albert P. Krueger, a microbiologist and experimental pathologist at the University of California, found that a small quantity of negative ions could kill bacteria and quickly remove them from the air, so that they were less likely to infect people.
Although negative ion Compact Fluorescent Lamps (CFLs) aren't considered a medical device, they significantly reduce a myriad of indoor air pollutants by emitting negative ions. Negative ions have known benefits, and may provide relief from sinus, migraine headaches allergies and hay fever, reduce the severity of asthma attacks, enhance the immune system, increase alertness, increase work productivity and concentration, increase lung capacity and reduce susceptibility to colds and flu.
Negative ion air purifiers work by electrifying molecules in the air. The negatively charged molecules then bind themselves to other gas particles in the air—be they viruses, dust, or bacteria—which become attracted to surrounding surfaces such as walls and furniture. By increasing the rate of precipitation and reducing the number of such particles floating in the air, the purifier lowers the risk of contamination in an enclosed space.
However, similar to chlorine dioxide gas emitters, its effectiveness drops dramatically outdoors where the air is dynamic. And the process of running air through an electrified plate generates ozone as a side product, so it is not advisable to have it on all the time.
As research shows, the physical action of air ions on particles and particulates have received a varied amount of attention, but the role of ionisers in regards to bacterial deposition and dissemination have been largely ignored. There is evidence from a clinical setting that air ions may play an important role in preventing transmission of certain infections. In trials conducted on an ICU, presence of negative air ionizers was associated with a signification decrease of a specific infection acinetobacter infection or patient colonisation, despite the fact that numbers of environmental isolates of colonisation was more than likely due to physical effects, rather than bacterial phenomena.
"Although the reasons for the results observed by Kerr et al. are unclear, it is hypothesized that the air ions may have negatively charged items of plastic medical equipment in the ward, such as patient ventilator tubes, so that they repelled, rather than attracted, airborne bacteria. Widespread aerial dissemination of bacteria is thought to occur within the clinical environment due to activities such as bed making, and this has been implicated in a number of outbreaks of Acinetobacter infection. In the course of normal operation, many items of plastic equipment naturally acquire an electric charge, and this can promote electrostatic precipitation of bacteria, carrying an opposed charge, from the air. By negatively charging both particles in the air and items of plastic equipment, the ionizers potentially minimize electrostatic deposition on these surfaces. In order to test this hypothesis we designed the experimental study to investigate the behaviour of items of plastic medical equipment in the presence of negative air ions and to assess the likely impact on the precipitation of airborne particles."
In conclusion, yes, negative ions can kill bacteria. This phenomenon is solely based on the relative concentration of ions (either positive or negative) on the outside when compared to the inside of the bacterial cells. Higher ionic concentration on the outside leads to the bacterial cells to lose water to the surrounding environment and hence die of dehydration. This is why salt or sugar curing protects foods from microbial contamination. Similar, water with absolutely no ions can also cause rapid influx of water into the bacteria leads to them bursts and hence bacterial cell death.
- National Library of Medicine, "Negative Air Ions and Their Effects on Human Health and Air Quality Improvement": https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213340/
- BMC Research, : https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-10-92
- Research Gate, BMC Microbiology: https://www.researchgate.net/publication/6388296_Bactericidal_action_of_positive_and_negative_ions_in_air
- WebMD, "Negative Ions Create Positive Vibes": https://www.webmd.com/balance/features/negative-ions-create-positive-vibes#1
- Mayya YS, Sapra BK, Khan A, Sunny F: Aerosol removal by unipolar ionization in indoor environments. Journal of Aerosol Science. 2004, 35: 923-941. 10.1016/j.jaerosci.2004.03.001.
- Beggs CB, Kerr KG, Noakes CJ, Hathway EA, Sleigh PA: The ventilation of multiple-bed hospital wards: review and analysis. Am J Infect Control. 2008, 36 (4): 250-259. 10.1016/j.ajic.2007.07.012.
- Bailey W. Mitchell and Daniel J. King, Avian Diseases, Vol. 38, No. 4 (Oct. - Dec., 1994), pp. 725-732
- Noakes C, Sleigh PA, Beggs CB: Modelling the air cleaning performance of negative air ionisers in ventilated rooms. Proceedings of the 10th international conference on air movement in rooms - Roomvent 2007: 13-15 June 2007; Helsinki. 2007, 1046-1056.