ASTHMA AND THE ENVIRONMENT
Air pollution
There are lots of things in the air we breathe that can make asthma symptoms
worse in some people with asthma. Air contains triggers which occur naturally
such as pollen, house-dust mite droppings and animal fur. It also contains
pollutants which are made by humans such as cigarette smoke and vehicle
exhaust. It is these 'unnatural' air pollutants which will be covered here.
Air pollution from burning fuel
Some airborne pollutants are created by the burning of fuels such as petrol,
coal and diesel, which all release gases and particulates into the atmosphere.
These gases can be toxic, posing a threat to the environment and to our health.
Air pollution is increasingly being linked to a variety of health problems.
Although the heavy industrial smogs of the 1950s have been cleaned up, the
increasing level of traffic on the roads and the likely rise in exhaust fumes
may begin to pose a threat to our health.
Air pollution from smoke and sulphur dioxide has fallen since the 1950s, and
now rarely exceeds the safe levels set by the EC and the World Health
Organisation. But other types of air pollution, such as nitrogen dioxide and
particles, are rising in some cities in the world.
Particle emissions from cars and lorries have increased by 75 per cent since
1980. Although all new petrol cars now have a catalytic converter to reduce
their fumes, there will still be a long delay before the older cars wear out
and the catalysts significantly reduce exhaust emissions. In the light of this,
exhaust fume emissions are forecast to fall until 2010. However, because the
Department of Transport predict between a 65-106 per cent increase in traffic
by the year 2025, emissions may then start to rise again. This rise may not
necessarily mean an increase in the amount of pollutants in the air. Some
areas, for instance, have steady rather than rising levels of nitrogen dioxide
and ozone despite the overall increase in traffic.
Air pollution can trigger asthma
The airways of a person with asthma are especially sensitive. When the air
quality is very poor and pollutants are concentrated, the air pollution mix in
the atmosphere can act directly on the lungs of people with asthma.
Asthma is increasing, particularly in western countries. Experts are
convinced that air pollution can trigger attacks in those people who already
have asthma, particularly those whose asthma is more severe. A study based in
Birmingham showed a significant association between those living near main
roads and hospital admissions of children under five with asthma attacks.
At present there is no evidence that proves air pollution actually causes
asthma to appear in someone who does not already have it. Some scientists
believe, however, that air pollutants may make the lungs more vulnerable to
viruses and allergic triggers such as pollen.
The main airborne pollutants affecting people with asthma
Sulphur dioxide (SO2) is produced when coal is burned. Since the
Clean Air Act of 1956, sulphur dioxide levels have decreased. Power stations
are by far the biggest contributors, although industrial and domestic use also
creates sulphur dioxide. This pollutant is particularly likely to cause
wheezing if inhaled during exercise. It is possible that in the long term SO2
exposure will be more likely to affect patients with asthma.
Particulates are small pieces of dust or dirt which are blown by the
wind, or produced as a result of burning fuels such as diesel and coal. In
towns and cities most particulates come from diesel vehicles. Some scientists
have expressed their concern that particulates may cause an increase in
symptoms in people with asthma.
Nitrogen dioxide (NO2) is in vehicle enussions (exhaust) from both
diesel and non-diesel engines. There is disagreement about whether NO2 is
important in asthma. It may irritate the airways, perhaps making them more
sensitive to allergens such as the house-dust rriite. It may also increase the
chance of your body picking up a viral infection, which can trigger asthma
symptoms. NO2 exposure is greatest, however, indoors, in homes with gas cookers
and gas fires. Children with asthma living in such homes have more symptoms.
Ground level ozone is part of a pattern of air pollution known as
'photochemical smog'; it is a particular problem during the sununer months.
Bright sunlight creates a chemical reaction in the air which produces ozone at
ground level. This should not be confused with the ozone high up in the
stratosphere which protects us from the sun's harmful ultra-violet light.
Ground level ozone can pose a real health risk to some people with asthma,
particularly children. It inflames the airways, reduces the ability of the
lungs to work properly and may worsen allergic reactions.
Acid air is caused by a reaction of gases, like nitrogen oxide and
sulphur dioxide, with water vapour. Very little is known about the levels of
acid air in Britain, but in the USA higher levels of acid air are associated
with symptoms of cough and phlegm.
Recording air pollution levels
Air pollution is monitored (recorded) throughout Britain, although we have
relatively few extensive monitoring sites compared with some other countries.
Some sites measure only one or two pollutants but other new sites measure
several different gases; further sites are being approved and will increase our
knowledge of levels. The older sites we have cannot record short peaks of
pollution which may be equally as important as the longer periods, but if the
government expands the number of new, automated sites as planned, then
researchers will have improved information.
In Britain there are few ozone and nitrogen dioxide monitoring stations and
none for acid air. As a result, there has been very little research on how they
affect our health.
To find out how bad the problem is, monitoring needs to be geographically
widened, including more nitrogen dioxide, ozone and perhaps acid air
measurements.
The real issue for people with asthma is what happens to the information
that is gathered by air quality monitoring. It could be very important in
helping answer the key outstanding questions, such as does pollution cause
asthma to develop in the first place?
Using the Department of Environment Pollution Helpline can point to when
people with asthma should increase their inhaled preventive treatment. However,
broad advice to stay indoors if the air quality is poor is not helpful or
necessarily correct, although the most severe will feel this is right for them.
Transport and other relevant policies need to be planned to take account of
public health issues.
Tobacco smoke
On average, we spend 90 per cent of our time indoors and the indoor
environment is very important indeed for most of us.
Tobacco smoke is the main pollutant that affects our health indoors. The
increasing discouragement of smoking in public places is good news for people
with asthma, many of whom are affected by breathing in other people's smoke.
Active smoking
Studies have shown that up to 20 per cent of people with asthma smoke.
People with asthma are particularly sensitive to the air they breathe, and
inhaling cigarette smoke worsens asthma symptoms by irritating the lungs and
causing airways to narrow. The airways of people with asthma are often narrow
on one day and normal the next, but with smokers the tightness often becomes
chronic and does not easily reverse (change back to normal).
A study of teenagers with asthma who smoked cigarettes showed they had
poorer asthma control and worse lung function by the time they reached their
twenties, and that their asthma had a tendency to persist. If you have asthma
and you smoke, you are increasing the risk of an attack and may be permanently
damaging your airways.
Smoking increases the risk of many health problems, but it can be tough
trying to give up. Some people try more than once before they manage to stop.
For advice, help and support on giving up smoking call Quitline on 020-7487
3000.
Passive smoking
Only 15 per cent of the smoke produced by a cigarette is inhaled by the
smoker. The rest streams out or is puffed out. A
National Asthma Campaign survey has
shown that cigarette smoke has been identified as capable of causing asthma
attacks in 83 per cent of people with asthma.
Smoking while pregnant poses many dangers to the baby, including an
increased risk they will have asthma. Passive smoking may also increase the
risk of the baby developing asthma.
What we can do about 'unnatural' air pollutants
Knowledge about the effects of air pollution does not protect our health on
its own. The information needs to be acted upon to ensure that our right to
breathe clean air is protected. There are steps we can take to help our asthma.
In the short term
Keep informed
Local newspapers and radio stations sometimes carry an air quality forecast
which will give you the most up to date information. You can also ring the
Department of the Environment's Pollution Helpline on 0800 556677 (calls are
free). This is an air quality information line (with a recorded message) which
gives a general comment for the day, a forecast of pollution levels, and
detailed figures for the previous day's ozone, nitrogen dioxide and sulphur
dioxode levels. Information is also available on Teletext (page 106) and Ceefax
(page 404).
Stay in control of your asthma
Monitor your symptoms by noticing how often you need reliever medicines and
perhaps recording your peak flow readings. Follow your self-management plan, if
you have one. Discuss any problems with your doctor or nurse.
Seek advice from your doctor
When pollution levels are high, and depending on how well you are, your
doctor may recommend that you increase your preventer and reliever treatment
(for up to three days after the air quality has improved).
Protect yourself
- Think twice before exercising outside on hot summer days when ozone levels
are likely to be highest, particularly in the afternoon.
- If you do exercise you may find wearing a mask with an activated carbon
filter helps, although there is no good evidence that masks are effective
against current levels of sulphur dioxide and particulates in Britain. Masks do
not protect against nitrogen dioxide.
- On cold days breathing through a scarf will help warm the air and may
reduce the chances of a pollutant acting with the cold air to make you wheeze.
- A lot of countries have a much greater problem
with air quality than Britain. Many cities throughout the world are more
polluted than those in Britain, particularly away from the coast. Ask about
pollution levels when you book a holiday and see our booklet 'Asthma and
holidays'.
Stay clear of cigarettes
Try to avoid cigarette smoke as much as possible.
Keep your workplace free of smoke
The right to breathe clean air is increasingly protected in the workplace.
If you are concerned please speak to your Health and Safety representative or
your trade union representative. Action on Smoking and Health (ASH) produce a
leaflet called Smoking at Work which contains advice for employees (further
information available on 020-7935 3519).
Longer term steps
- Write to your MP Tell him or her what 'unnatural' pollutants are doing to
you, giving any evidence you have. Ask for a reply that tells you what he or
she plans to do to help attack air pollution, both indoors and outdoors.
- Write to your local paper and try to get the story of 'unnatural' air
pollution and your asthma featured in local media. Write to national papers
too.
- Get your local National Asthma
Campaign branch to hold meetings on the issue, either alone or in
partnership with a local environmental group.
- Write to the National Asthma
Campaignwith information about any campaigning you have done on smoking or
air pollution issues. If you need campaigning advice please contact a local
environmental group like Friends of the Earth or Greenpeace.
- The charity publicises the links between asthma and air pollution but does
not recommend a particular app-roach to reducing it or campaign on planning
issues.
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