Biological pollutants - '

Another category of major household pollutants is the naturally occurring insect and microbial life that chooses to share our homes with us principally house dust mites and moulds. Mites are a major culprit in causing allergies. They feed on skin cells and breed in mattresses, pillows, carpets and upholstery. There are an estimated 100,000 of them in every square yard of carpet.

Moulds, however, are potentially more dangerous. Relatives of mushrooms, some moulds can be as toxic as the most hazardous man made chemicals.To minimise your exposure to dustmites or mould:

Keep the bedroom uncluttered and easy to clean.

Regularly vacuum mattresses, box springs and pillows, or better still encase them in air tight, zipped up plastic covers.

Before vacuuming, dust furniture, windowsills and crevices with a slightly damp cloth.

Wash all bedding regularly in hot water (at least 130 degrees F) to kill dust mites.

Choose Dacron or Orlon pillows and replace every two years.

Remove as much carpeting as possible; replace with wood or vinyl flooring. In order to prevent mould, do not use carpets in bathrooms.

Keep the house humidity levels low (between 30 and 50 per cent) with either a dehumidifier or air conditioning.

Use a vacuum cleaner with a HEPA (high efficiency particulate air) or the newer ULPA (ultra low penetration air) filter. Vacuuming won't suck up the dust mites themselves they are great at clinging to fibres but it will remove their droppings and decomposing body parts.

Ventilate the bathroom daily to ensure that walls and curtains get dry.

Clean baths, showers and curtains monthly with a 1:10 bleach to water solution to kill mould.

Clean all air filtering appliances regularly.