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Don't Pull Up Your Carpets

Recent publicity suggesting that asthma sufferers take up their carpets is based on a widespread misconception, according to Dr Peter Ingham, who leads researchers looking into these issues at the Wool Research Organisation of New Zealand.

"The idea that removing carpets will help asthma sufferers has been with us for a number of years, Ingham says. "The problem is that these ideas are based on counts of allergens contained in dust sucked up out of the carpet by extremely high-powered vacuum cleaners. In comparison, hard flooring surfaces yield less dust, and hence less allergens, and so it is tempting to conclude that removing the carpet will solve the problem.

"However, without that suction most of the allergen-bearing dust will remain trapped in the carpet pile, whereas on a smooth surface the slightest disturbance will puff the very fine allergens up into the air and distribute them throughout the house. The allergens can remain suspended in the air for up to 24 hours and so are readily inhaled during normal daily activity.

"Thus although it is well documented that dust mites are a common source of allergens that produce adverse effects on the respiratory system, carpets are not the main culprit. In fact, carpets provide something of a hostile environment for dust mites since they are too dry, too cold and too exposed to light," he says.

Extensive international research has revealed that bedding forms the main habitat and breeding ground for dust mites, being protected and less regularly cleaned but, more importantly, creating warm, moist conditions necessary for dust mites to survive. The conditions must be moist so the dust mites can feed, Ingham says.

Ingham cites the conclusions of Dr John Maunder, Director of the Medical Entomology Centre of the University of Cambridge:

There is no reason why asthmatics should not enjoy a fully carpeted bedroom as long as the air is dry, the ventilation good and the cleaning regular.