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As DEFRA's leaflet is now being updated to incorporate
the new banding system, the Committee has been asked for its approval
of the health advice contained within this leaflet. Much of the wording
in the leaflet is based on previous leaflets and on statements agreed
by the Committee. Therefore, detailed comments on the entire leaflet
are not required. The Committee's views are however invited on extracts
from leaflet, as listed below;
Heart Disease
Currently, the leaflet contains only the following text,
based on previous discussions with the Committee.
'People with heart conditions or severe lung disease (e.g.
chronic bronchitis or emphysema) might be more sensitive to changes
in air pollution than the descriptions suggest. If you suffer from a
heart condition and you notice a change in your symptoms get
medical advice as you normally would. Do not try to change your treatment
yourself.
In previous discussions, the Committee has been wary of
saying too much about heart disease since so little is known about who
is affected. There are now more papers on heart disease, does this mean
that the Committee would like to change its view? DEFRA have asked whether
any more can be said on heart disease in the leaflet.
Effects of Long Term Exposure
Views on the previous leaflet from focus groups suggested
that the public wanted to know about long term effects. The new leaflet
now contains the following paragraph.
'The Information Service only provides information about
the short-term health effects of certain air pollutants. Air pollution
is also likely to have an effect on health over the longer term. Understanding
of the long-term health effects of exposure to air pollution is currently
rather limited, but the latest scientific advice is that the long-term
health effects may be more significant than the short-term effects.'
The Committee may wish to comment on this (the Secretariat
notes that effects of short term exposure would be a better term than
short term effects). As the leaflet is intended to be short, extensive
additional text would be difficult to incorporate but there is an opportunity
for further information to be included in the Committee's internet statement
on health advice (see below).
Where Should I Live?
The leaflet also contains a section called 'Where Should
I Live'. Although this is considered a difficult, if not unanswerable
question, DEFRA considered it should form part of the leaflet because
it is such a frequently asked question. The Committee may wish to comment
on this.
'Individuals have different levels of sensitivity to different
air pollutants. It is therefore very difficult to produce a simple map
of areas of clean air where susceptible people might wish to live. If
you are worried about air pollution, you may wish to discuss this with
the local authority environmental health officer in your area or in
one where you might like to move to. Air pollution is only one of many
potential triggers for symptoms of asthma, so moving to an area with
lower pollution may not always help to reduce your symptoms..'
The Committee's Internet Statement
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The COMEAP website contains an agreed paper 'The Health
Effects of Air Pollutants: Advice from the Committee on the Medical
Effects of Air Pollutants' (copy attached). Although this statement
has already been agreed by the Committee, the Committee is invited
to review several sections of the statement, as follows;
Heart Disease
Section 3.3
'The number of deaths and hospital admissions that occur each day
varies and both seem to go up when air pollution levels are high,
particularly for those with cardiovascular and lung disorders and
especially amongst the elderly.'
This is the only reference to cardiovascular disease. Would the Committee
like to expand on this, as discussed above?
Effects of Long Term Exposure
Section 4.2
The paragraph below currently appear in the Committee's health advice
paper
'The scientific evidence suggests that exposure to air pollution
has a long-term effect on health, though the effects will vary depending
where one lives (urban or rural) and the type of pollutant to which
one is predominantly exposed. The full extent of this is hard to quantify,
but one suggestion is that across the population as a whole life expectancy
might be reduced, on average, by as much as one year. To put this
in context, the average reduction in life expectancy caused by smoking
is eight years. How the pollutants act is not clearly understood but
the normal decline in lung function that occurs in all of us with
age may be accelerated by exposure to air pollutants; and this would
be particularly noticeable and serious for smokers whose lung function
would already be in decline. This may contribute to the reduction
in life expectancy that is found in highly polluted areas compared
to relatively clean areas, but there are other lifestyle factors,
such as diet and smoking, that can make a much larger contribution.'
The suggested reduction in life expectancy was based on a paper by
Brunenkreef (Brunenkreef, 1997) but the Committee now has its own
estimate made in the report on the long term effects of particles
(paragraph 55). The discussion of an effect on the normal decline
in lung function may also need amending since the HEI reanalysis found
that the relative risk for all cause mortality of those with an FEV1
<85% of predicted (RR 1.35(1.00-1.84)) was not significantly different
from the relative risk of those with an FEV1 >85% of
predicted (RR 1.24(1.03-1.49)) although there was a slight increase.
Also, the finding that it was cardiovascular rather than respiratory
disease mortality that was affected, does not support the idea that
a decline in lung function is likely to ba a major mechanism. A suggested
amended paragraph is given below for the Committee's comments:
'….The full extent of this is hard to quantify, but the Committee
has estimated that life expectancy from birth might be reduced, on
average, by between 2 and 20 months (depending on assumptions) as
a result of life long exposure to current levels of fine particles.
To put this in context, reduction in life expectancy caused by smoking
is around 7 years. Other lifestyle factors such as diet can also make
a large contribution. The mechanism for this effect of long term exposure
to particles is not understood. It appears to mainly affect deaths
from heart disease.'
Brunekreef B. Air pollution and life expectancy: is there
a relation? Occup Environ Med 1997; 54:781-784.
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