The following is a totally subjective and unscientific report of some
tests I've done with allergen avoidance with the hope of improving
my symptoms.  The measures and results I describe below may or may not be
of use to anyone else, and are offered for interest only.

A few months ago I posted that I'd started a trial with an inflatable
mattress and some other allergen avoidance measures to see if this
would have an effect on my asthma symptoms.  I'm highly allergic to
house-dust mite (I got the maximum RAST test score for dustmite allergy),
hence the measures I've taken.

So far I've seen a definite improvment in my symptoms, especially night-time
wheezing.  My maximum daytime peak flow measurement hasn't increased,
but the number of times I wake up during the night needing albuterol
has dropped substantially, from perhaps 2-5 to only around 1 now, in fact
it's now quite common for me to sleep throughout the whole night without
being woken by bronchospasm, which hardly ever happened before I made
these changes.  My daytime breathing is also somewhat easier, but the
main improvment is apparant at night.  I've been able to halve my
daily inhaled steroid dose (fluticasone - flixotide) (done under the
supervision of my GP) with no worsening of symptoms.  There has been
no other change to my medication.  I've also noticed that my nasal
congestion has reduced greatly, again particularly noticable at night.

I'm really very pleased with these results so far, which has been sustained
for about the last 3 months.  It remains to be seen whether this
improvement will be maintained throughout the spring/summer pollen season
and increased air pollution in the summer (higher ozone levels than in
winter).  However, my asthma symptoms this winter are definitely much better
than they were last winter.  I've noticed that I seem to be catching fewer
colds this winter as well, although that may just be a coincidence.

The main measures I've taken in the bedroom are as follows:-

1. I threw out the normal mattress and replaced it with an inflatable
PVC mattress, with the aim of eliminating the largest dust-mite reservoir
in the room.  (Note - to anyone thinking of doing this, blow the mattress
up and let it stand in the garage for a few days before you sleep on it,
they tend to offgas a lot the first few days they are used).

I'd previously tried anti dust-mite covers on the old mattress but didn't
get the same improvement in my symptoms as I have with replacing the
mattress with the airbed.  I haven't tried foam or latex mattresses
or a waterbed.

2. The bed base that the airbed rests on is a divan box type with draws,
ie it's basically a wooden box so it doesn't contain fabric or springs
or stuffing.

3. I removed the padded fabric-covered headboard from the bed and
stored it in the garage.

4. I threw out all the old bedding and replaced with all new pillows and
duvets (comforters).  I've covered the pillows and duvets with dustmite proof
anti-allergen covers.  

5. I discard the pillows and duvets every 3 months and replace with new.  
This may seem a little extreme, however as a double bed duvet costs 10 pounds
(about 18 dollars) and two pillows cost 5 pounds (9 dollars) in ASDA
(the UK subsidiary of Wal-Mart), it's actually cheaper to buy new than the cost
of laundering the bedding at a commercial laundery.  When you chuck them out,
you automatically discard any mites and/or fungi and/or bacteria that they
contain.  (However, I'm thinking that maybe I've been a bit too extreme here,
and could probably have kept them for 6 months).

The pillows and duvets I use are the cheapest available type, which have bonded
polypropylene covers rather than the more expensive types that have cotton
covers.  I've found them just as comfortable to sleep in as the cotton
covered ones.

6. Replaced bedroom curtains with a plain roller-blind that can be wiped
clean with a damp cloth.

7. I have no soft furnishings or toys in the bedroom, no books or magazines,
no ornaments or lampshades or other dust traps.  OK, it's a bit spartan,
but there's nowhere for the mites to hide (except the carpet).

8. I had some old coats and other clothes in the wardrobe; I threw the
lot out.

9. I bought two vacuum cleaners:-
- Dyson HEPA filter "allergy" vacuum cleaner for the carpet;
- Miele HEPA filter "allervac" for general cleaning.

The bedroom has a short pile carpet, I was going to discard this
but thought I'd give the vacuum cleaners a try first.  The first time
I used the Dyson I was amazed at the amount of muck it pulled out of
the carpet.  I'm not very impressed with dyson build quality though - flimsy
plastic construction, I don't know how long it will last.  I wouldn't
particularly recommend these cleaners over other types, I bought them because
I happened to see them on special offer in local stores.  I got the miele
first but was disappointed that the suction decreased greatly when the
bag isn't even half full, so I decided to try the dyson as well.

I vacuum the bedroom carpet every 2-3 days with the dyson and use the
miele to vacuum all the nooks and crannies that are less convenient to get
at with the dyson.  I vacuum the whole house with these two cleaners
every few days, and at least once a week.  I damp dust the window-sill
and other flat surfaces at the same time.

-- gumbo