Asthma is a very common
long-term condition; at least one child
in 10 and about one adult in 20 have asthma.
It can be so mild that it's hardly noticeable,
or it can come on suddenly and be so severe
that the affected person may panic. Most
cases are somewhere in between. Asthma affects
the breathing, making it harder to get enough
breath, and causing wheezing, coughing and
a strong feeling that the air can't get
in or out of the lungs. This feeling is
caused when the airways narrow.
Asthma is partly an
allergic problem, and there is a connection
between asthma, hay fever and the skin condition
eczema. This is because all three conditions
are related to a single one of the genes
inherited from your parents. Because of
this genetic connection, these three conditions
run in families, sometimes causing asthma,
sometimes hay fever and sometimes eczema.
Some people may have more than one of these.
Asthma doesn't cause
trouble all the time. Attacks may sometimes
occur quite often, but in many cases the
person with asthma is free from the trouble
for quite long periods.
More than most disorders,
asthma is a 'self-help' condition in which
the affected person can do much to prevent
attacks. And when attacks do happen they
can usually be stopped fairly quickly.
However, it is not
a trivial disease – at least 2000
people die from it each year in the UK,
and most of those deaths are avoidable if
people know how to recognise the danger
signs.
Causes
The smaller air tubes in the lungs are much
narrower than most people realise, and these
tubes don't have to get much narrower for
it to be very hard for the air to get through.
The tubes, called bronchioles, have circular
muscles in their walls. In asthma the muscles
are may tighten (as part of an allergic
response or for no obvious reason) so that
some or most of the tubes are narrowed.
The passage of air in and out of the tiny
air sacs where oxygen passes into the blood
is partly or almost completely blocked.
On top of this, asthma
also features swelling of the lining of
the air tubes. The linings also have tiny
glands that push out mucus, and with asthma
there is an increase in mucus production
that also tends to block the air passage.
An asthma attack can
be started by breathing in, or contact with,
quite a number of different things. These
include:
- Pollens or fungal
spores
- Viral and bacterial
chest infections
- Animal allergen
or house dust mite
- Food additives,
such as tartrazine
- Seasonal changes
- Strong smells or
perfumes
- Smoke pollution,
or vehicle exhaust fumes
- Worry and stress
- Some medicines,
especially beta-blockers and aspirin
- Alcohol
- Nuts
- Shellfish
- Some fruits
- Heavy exercise,
especially when it's cold.
The forms of asthma can be divided into
two groups – those with a known cause
and those without. The first group mainly
affects people with a general condition
called atopy. This is a genetic condition
that makes people allergic to various substances
(allergens). It also increases the likelihood
of eczema and hay fever and there is often
a family history of these conditions.
The second group are
more likely to have developed asthma as
a result of exposure to industrial or atmospheric
pollution, or drugs such as NSAIDs (non-steroidal
anti-inflammatory drugs) and beta blockers.
Well over 200 industrial substances are
known to bring on asthma.
People with atopy
are also more likely to develop asthma in
response to industrial and other pollutants
than are people who do not have atopy, and
to do so more quickly.
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Asthma
