Air ioniser

Source: Wikipedia, the free encyclopedia.
This article is about the air purifier. For the controversial psychiatric treatment, see Negative air ionization therapy.

Salmonella enteritidis
. The left sample is untreated; the right, treated.

An air ioniser (or negative ion generator or Chizhevsky's chandelier) is a device that uses

Cations
are positive ions missing one or more electrons, resulting in a net positive charge. Some commercial air purifiers are designed to generate negative ions. Another type of air ioniser is the electrostatic discharge (ESD) ioniser (balanced ion generator) used to neutralise static charge.

History

In 1918 Alexander Chizhevsky created the first air ioniser for ion therapy.[1] It was originally used for animal health in agriculture.[2] This discovery ignited Cecil Alfred "Coppy" Laws' interest in the phenomenon of air ionisation. Laws has been credited with being the inventor of the domestic air ioniser.[1]

Ionic air purifiers

Air ioniser and purifier with its dust collection plates removed

Air ionisers are used in

nosocomial infections in British hospitals prompted the National Health Service (NHS) to research the effectiveness of anions for air purification, finding that repeated airborne acinetobacter infections in a ward were eliminated after the installation of a negative air ioniser — a promising result, although more evidence is necessary to determine if these results can be repeated.[4] Positive and negative ions produced by air conditioning systems have also been found by a manufacturer to inactivate viruses including influenza.[4][medical citation needed
]

A 2018 review found that negative air ions are highly effective in removing particulate matter from air.[5]

The

SARS epidemic fuelled the desire for personal ionisers in East Asia, including Japan (where many products have been specialised to contain negative ion generators, including toothbrushes, refrigerators, air conditioners, air cleaners, and washing machines
). There are no specific standards for these devices.

There are two types of ionic air purifiers, the fanless and fan base ionizers. The fan base ionizer uses its fan to circulate air around the room rapidly, but it is noisier and consumes more energy, while the fanless types distribute air slowly, taking a longer time to purify air, but are noiseless and more energy efficient.

Ions versus ozone

Ionisers are distinct from

UV light.[7]

At concentrations that do not exceed public health standards, ozone has been found to have little potential to remove

bacteria, and may destroy or kill these sometimes infectious organisms. However, the required concentrations are sufficiently toxic to humans and animals that the U.S. FDA declares that ozone has no place in medical treatment[9] and has taken action against businesses that offer ozone generators or ozone therapy to consumers.[10] Ozone is a highly toxic and extremely reactive gas.[11] A higher daily average than 0.1 ppm (100 ppb, 0.2 mg/m3) is not recommended and can damage the lungs and olfactory bulb cells directly.[12]

Health effects

A 2013 comprehensive review of 80 years of research into air ions and respiratory function outcomes found that there was no clear support for any beneficial role in respiratory function, nor evidence for significant detrimental effect. In conclusion, "exposure to negative or positive air ions does not appear to play an appreciable role in respiratory function."[13]

There is weak evidence that negative air ionization is associated with lower depression scores, particularly at the highest exposure level. No consistent influence of positive or negative air ionization on anxiety, mood, relaxation, sleep, and personal comfort measures was observed.[14]

Adverse health effects of ozone byproduct

Studies have been carried out on negative ion generators. One study shows that the ozone generated can exceed guidelines in small, non ventilated areas.[15] Another study showed that ozone can react with other constituents, namely cleaning agents to increase pollutants such as formaldehyde; this study's objective was testing for health risks associated with indoor use of cleaning products and air fresheners as opposed to adverse health effects of air ionisers.[16]

Consumer Reports court case

The Sharper Image, a manufacturer of air ionisers (among other products), sued Consumer's Union (the publishers of Consumer Reports) for product defamation. Consumer Reports gave the Ionic Breeze and other popular units a "fail" because they have a low clean air delivery rate
(CADR). CADR measures the amount of filtered air circulated during a short period of time, and was originally designed to rate media-based air cleaners. The Sharper Image claimed that this test was a poor way to rate the Ionic Breeze, since it does not take into account other features, such as 24-hour-a-day continuous cleaning, ease of maintenance, and silent operation.

The United States District Court for the Northern District of California dismissed the case, reasoning that the Sharper Image had failed to demonstrate that it could prove any of the statements made by Consumer Reports were false. The court's final ruling in May 2005 ordered the Sharper Image to pay US$525,000 for Consumer Union's legal expenses.[17]

Electrostatic neutraliser in electronics

Air ionisers are often used in places where work is done involving

non-conductors
. As those elements are very sensitive to electricity, they cannot be grounded because the discharge will destroy them as well. Usually, the work is done over a special dissipative table mat, which allows a very slow discharge, and under the air gush of an ioniser. The ionization falls off very sharply with distance (even in ducting), so air ionization is rarely used for this purpose, and only for items immediately adjacent to the actual ionizer.

Standards

The California Air Resources Board has a page listing air cleaners (many with ionizers) meeting their indoor ozone limit of 0.050 parts per million.[18]

See also

References

  1. ^ a b Pat Williams. "Obituary of Coppy Laws", Thr Independent, London, England, 4 June 2002
  2. ^ Churilov, Leonid (2017). "Master and Woland: In 120th Birthday Anniversary of Aleksandr Leonidovich Chizhevsky". Russian Biomedical Research. 2 (3): 23.
  3. doi:10.4209/aaqr.2010.06.0048
    .
  4. ^
    The New Scientist
    . No. Daily news. Retrieved 24 August 2016.
  5. PMID 30274196
    .
  6. S2CID 53334911
    .
  7. ISSN 1944-8007
    .
  8. ^ Woolston, Chris (21 April 2008). "Ionic purifiers' dirty secret". Los Angeles Times. No. The Healthy Skeptic. Retrieved 24 August 2016.
  9. ^ "CFR – Code of Federal Regulations Title 21". www.accessdata.fda.gov. Retrieved 2017-04-26.
  10. PMID 10628316
    .
  11. ^ "Ozone: Good Up High, Bad Nearby". Environmental Protection Agency (EPA) Website. Retrieved 2006-08-30.
  12. ^ "Occupational Health Guideline for Ozone" (PDF). Centers for Disease Control and Prevention.
  13. PMID 24016271
    .
  14. PMID 23320516
    .
  15. ^ "Quantification of Ozone Levels in Indoor Environments Generated by Ionization and Ozonolysis Air Purifiers" (PDF). Air & Waste Manage. Assoc. 56:601–610. May 2006.
  16. ^ "Indoor Air Chemistry: Cleaning Agents, Ozone and Toxic Air Contaminants" (PDF). April 2006.
  17. ^ "Sharper Image pays $525,000 to end lawsuit against CU". Consumer Reports. 2006-08-06. Archived from the original on 2007-10-17.
  18. ^ "List of CARB-Certified Air Cleaning Devices". Retrieved 2022-02-11.

Further reading

External links

Wikimedia Commons has media related to ionisers.
Look up ioniser in Wiktionary, the free dictionary.
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