Remember to change bags and clean fabric filters regularly. If changing bags or cleaning filters upsets you, enlist someone to do it for you.

The Medivac is available from The Healthy House or direct from Medivac. The Nilfisk is available from Allerayde or direct from Nilfisk. All these suppliers offer a trial period. Other suppliers of allergy vacuum cleaners are BVC, AEG, Miele, Rainbow and Vorwerk. Addresses and telephone numbers below.

The Rainbow machine is worthy of particular mention since users report that they find it more effective than the Medivac or Nilfisk. Dusts and dirt are removed by passing through water and there are therefore no bags to change, or filters to clean.

If you absolutely cannot afford to buy such a cleaner, another option is to try exhaust filters, available from Allerayde. These are made of fabric which you tape over the exhaust of any conventional cylinder cleaner, and most hard cased upright cleaners. The fabric is thick synthetic wadding, but has not been reported to cause any reactions. These filters are not as effective as the filtration cleaners. Tests have shown that they are slightly less efficient at trapping particles, and they let out through slightly larger particles. But they still trap over 99 per cent of particles over 0.5 micron in size, which covers most important allergens.

The filters cost $30 for three filters, and last about 24 hours of vacuum use. For most people, this would mean replacing them every 12 weeks or so. This is a cheaper solution than buying a filtration cleaner over the long term, unless you use a vacuum cleaner very heavily. Drawbacks are, however, that you are exposed to dusts on changing niters and that it can be fiddly to fix the filters on properly. Again, enlist someone’s help to do it for you if you need to avoid dusts.

Using exhaust filters may be a help if you go away for some time – on holiday or on a prolonged visit.
They may also help to use for a trial period while you decide whether thorough vacuuming will be of benefit to you long term.

Hoover sell High Filtration dust bags for their Turbopower and Turbomaster upright cleaners, which are claimed to reduce the amount of dust passing. A Which? survey found that ‘these gave only a small improvement over their other bags and that they still let through an unsatisfactory quantity of dust’.

Contact a local allergy support group, or a local group of a national charity, to see if they have members willing to lend you an allergy vacuum cleaner to try for a while.