There are three basic types of air clearing and filtering device:

• air purifiers

• ionisers

• air filters and cleaners

There are also built-in, and radiator systems, discussed below.

Air Purifiers

Air purifiers are on sale in many High Street shops. They are small electrical devices, relatively cheap (about £15 at 1992) and work by drawing the room air in, and passing it through a thin fabric filter and over a perfumed insert. They are sometimes called fragrancers or vapourisers. Their main function is to mask smells and they are not very effective at removing either particles or vapours. They are generally of little benefit to people with allergy or sensitivity, and the fragrances can upset the chemically sensitive.

Ionisers

Ionisers work by producing negative ions. Dust and other particles have a positive electrical charge and are often suspended in the air. The negative ions from an ioniser neutralise the positive charge and the particles from the air are attracted to the walls and floor. The air is thus cleared by particles being attracted to other surfaces, not by them being filtered or removed. Ionisers do not remove chemical fumes or vapours.

Studies carried out on the effectiveness of ionisers in reducing the level of airborne allergens have failed to produce any evidence that they actually help allergic respiratory problems. The National Asthma Campaign does not endorse them. However, people who use them often do feel that they bring benefit. In March 1992, a Which? survey of 130 people who wrote to the magazine about ionisers reported that slightly more of them ‘thought that their ioniser helped them, compared with those who thought it had not’. Which? tests also found that ionisers can clear cigarette smoke much more quickly than allowing the smoke to disperse or settle naturally.

One major drawback of ionisers is that the dirt clings to walls behind furniture and around the edges of furniture and objects. The dirt is often greasy and difficult to clean, creating permanent dark marks for which the only solution is to redecorate – a serious disadvantage if you are chemically sensitive.

The simplest ionisers are relatively cheap (from £25 at 1992 prices), light and portable. They are usually of hard plastic cases which do not upset the chemically sensitive once aired. Ionisers are also often built into other filtering devices (see below).

The Which? survey (March 1992) found that a number of makes of ioniser did not actually produce ions on test. The Pifco 1072 (£25) performed best on their tests.

Ionisers are readily available from electrical shops and wholefood shops. They are also available by mail order from the Air Improvement Centre, Allerayde, The Healthy House, The London Ioniser Centre and Medivac.

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