PEOPLE who are prone to allergy should be cautious when they move house and always check if the previous occupants owned a cat, according to Dr Paul Cullinan, lecturer in respiratory medicine. It takes up to 18 months for airborne allergens to disappear from a house which has been inhabited by cats, he says in the General Practitioner.

Unlike house dust mite allergen, which is relatively heavy and sinks to the floor, cat allergen - made up of skin and hair - float around in very fine particles, causing people to wheeze as soon as they enter a room.

A nurse who specialises in allergy has recommended storing fur toys in the freezer to reduce the numbers of dust mites, whose faeces trigger asthma in some children. Cuddly toys can harbour many dust mites, but they do not always wash well, says Mary Brydon, a nurse practitioner. A few days inside a polythene bag in the freezer will dramatically reduce the number of mites.