There are some pretty nasty things lurking in carpets. When it comes to a cleaner house, floorboards were long thought to leave carpets for dead. Those with allergies were told to avoid the plush pile at all costs.

Allergy sufferer Alison Fan thought carpet may be the culprit causing her allergies.

"Well we thought that we'd go for a cleaner look ... and I thought it might help the allergies, and did it? Not a bit," allergy sufferer Alison Fan said.

Ms Fan thought floorboards would see the end of her sneezing and wheezing.

Six months on, not only are her allergies no better, she can't keep up with the dust.

"All you need is a draught and you see the dust ... it drives you crazy," she said.

"The worst thing of all, of course, is if you've got an animal. I mean look at this fluff. It just comes off and gathers together."

Now Ms Fan believes floorboards do not deserve the clean-living reputation they have had.

Environmental scientist Dr Peter Dingle has long championed the cause of cleaner allergy-free homes.

But the idea floorboards are cleaner is an urban myth, he says.

Dr Dingle says scientific tests are in fact finding carpets are healthier than floorboards.

"The Asthma Foundation, doctors and other medicos (have) stopped telling people to remove their carpets," he said.

To prove which surface improved the levels of dust, tests were done on 10 homes with wall-to-wall carpet and 10 homes with hard floor surfaces using a three-stage monitor and vacuum pump.

Dr Dingle says the results showed dust everywhere, on the floor and in the air.

But there was no more or less in either the carpeted home or the floorboard home.

"So essentially there wasn't any difference between the amount of microscopic dust in the air on both of those environments," he said.

He said in some cases, homes with carpet had less dust and bugs in the air.

"Carpets are a very effective trap and that's what they're very good at, actually removing the toxins. Because of the fibres they lock it down in the deeper parts," he said.

Now that is not to say that some allergy sufferers won't benefit from removing carpets.

Dr Dingle says if carpets are filthy, removing them may help.

But if your floorboards are not cleaned regularly, you could have the same problem.

Researcher Ben McCarthy tested three methods - steam cleaning, dry cleaning and extraction.

He found the degree of cleanliness varies markedly between each one.

"Quite often many of the varying methods professional carpet cleaners use, like so-called dry cleaning and agitating, doesn't actually remove much particular matter and associated toxins and allergies out of the carpet at all," he said.

Mr McCarthy collected samples for analysis using a filter and dust trap attached to the vacuum.

Of all three methods, hot water extraction was found to remove the most dirt.

"Well your general service dry clean was shown to make a 19 per cent improvement in reducing the dirt that's in your carpet," he said.

Hot water extraction gave a 74 per cent improvement.

A good extraction clean should take several hours as it removes more dirt using fewer chemicals.