Air ioniser

Lore & Background

Around 1927, Alexander Chizhevsky developed his first 'chandelier' for ion therapy, originally used for animal health in agriculture. This discovery ignited Cecil Alfred 'Coppy' Laws' interest in air ionisation, and Laws has been credited with inventing the domestic air ioniser.

Air ionisers are used in air purifiers to remove particles from air. Airborne particles become charged as they attract charged ions from the ioniser by electrostatic attraction, then are attracted to nearby earthed conductors. The frequency of nosocomial infections in British hospitals prompted the National Health Service to research anions for air purification, finding that repeated airborne Acinetobacter infections in a ward were eliminated after installing a negative air ioniser, though more evidence is needed.

There are two types of ionic air purifiers: fanless and fan-based. Fan-based ionisers circulate air rapidly but are noisier and consume more energy, while fanless types distribute air slowly, are noiseless, and more energy efficient. Ionisers are distinct from ozone generators, though both operate similarly; even the best ionisers produce a small amount of unwanted ozone.

Reader's Guide

Air ionisers have significance in both air purification and static electricity control. They are used in microelectronics cleanrooms to eliminate static charge build-up on non-conductors, as sensitive components cannot be grounded. In air purification, a 2018 review found negative air ions highly effective in removing particulate matter from air. However, a 2013 comprehensive review of 80 years of research found no clear support for beneficial effects on respiratory function, nor evidence of significant detriment. Weak evidence suggests negative air ionization may be associated with lower depression scores at high exposure levels, but no consistent influence on anxiety, mood, or sleep was observed. The devices can produce ozone as a byproduct; studies show ozone can exceed guidelines in small, non-ventilated areas and may react with cleaning agents to increase pollutants. Consumer Reports gave some ionisers a 'fail' due to low clean air delivery rate, leading to a lawsuit by The Sharper Image that was dismissed, with the court ordering the manufacturer to pay legal expenses. The California Air Resources Board lists air cleaners meeting an indoor ozone limit of 0.050 parts per million.

Did You Know?

• Alexander Chizhevsky developed his first 'chandelier' around 1927 for ion therapy, originally used for animal health in agriculture.
• Cecil Alfred 'Coppy' Laws has been credited with inventing the domestic air ioniser.
• A 2018 review found negative air ions are highly effective in removing particulate matter from air.
• The Sharper Image sued Consumer Reports over a negative review of air ionisers, but the case was settled in 2005 with no money changing hands.