Air Quality & Health
Poor air quality has been linked to respiratory health effects. The major air pollution episodes of
the 1950's and 60's are now thankfully a thing of the past in the UK. This does not mean though that air
pollution is not of concern. Rising levels of road traffic, increasing industrial activity and even new
homes all represent sources of air pollution.
The focus for outdoor air quality in the UK is on the prevention and minimisation of health effects
on persons vulnerable to air pollution. To this end the National Air Quality Strategy provides standards
for eight pollutants and a date by when they should be met. Compliance with these standards should indicate
that there are no measurable health effects attributable to air pollution.
Sussex-air runs the airAlert service in Sussex, to provide air pollution alerts to respiratory vulnerable people.
This service forecasts and provides an early warning to vulnerable people, so that they can mange their health.
To find out more visit www.airalert.info.
Health Advice
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Particulate Matter
A lot of focus in the field of air pollution and health is currently centred on fine particulate matter.
Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of the
condition of people with heart and lung diseases. In addition, they may carry surface-absorbed carcinogenic
compounds into the lungs.
Scanning Electron Microscope: Image of a particulate matter sample (soot).
Of particular concern is PM10 (dust less than 10 µm in diameter). There are difficulties in controlling this pollutant,
as it is derived from naturally occurring sources (such as wind blown soil and plant matter) as well as vehicle and
industrial pollutants.
Particles are measured in a number of different size fractions according to their mean aerodynamic diameter.
Most monitoring is currently focussed on PM10, but the finer fractions such as PM2.5 and PM1 are becoming of
increasing interest in terms of health effects.
Ozone
Ozone is what is referred to as a "secondary" pollutant. That is, there are no direct emissions of ozone into
the atmosphere. The ozone is formed as a result of the action of sunlight on other pollutants present in the atmosphere
(such as nitrogen oxides and volatile organic compounds). This means that local control of ozone pollution is difficult,
and hence it is not one of the pollutants dealt with under the local air quality management regime.
Ozone is a particular problem during summer months (May to August), and concentrations tend to be higher in the
south-east than elsewhere in the UK, due to our proximity to continental sources of the chemicals which form ozone.
Exposure to high concentrations of ozone may cause irritation of the eyes and nose, but typical peak levels are
more usually associated with airway irritation and related effects.
Nitrogen Dioxide
There are a number of oxides of nitrogen present in the atmosphere, but it is nitrogen dioxide which
gives rise to health concerns. Nitrogen dioxide is a respiratory irritant, and is also thought to be a
sensitiser, which may worsen other conditions such as hayfever. Nitrogen dioxide can irritate the lungs
and also lower resistance to respiratory infections such as influenza. Continued or frequent exposure to
concentrations that are typically much higher than those normally found in the ambient air may cause
increased incidence of acute respiratory illness in children.
Nitrogen dioxide is the pollutant for which there is the most local monitoring. This is because cheap and
relatively simple monitoring equipment is available to monitor nitrogen dioxide.
Most districts have at least four sites, which participate in a national survey of
nitrogen dioxide which has been running for a number of years. More sophisticated monitoring
equipment is also in use, giving hourly readings of nitrogen dioxide concentration.
Results from within Sussex show that at certain kerbside (within 1 metre of the road) locations the annual
average (40 µg/m3) objective is currently being breached, as well as at a small number of intermediate sites
(1-30 m of the road). Data from the DEFRA run Lullington Heath site (near Eastbourne) and in Brighton and Hove
suggest that the hourly maximum standard (150 ppb) is not currently exceeded in Sussex.
Others
Benzene is a known human carcinogen (cancer causing substance), and also contributes to the formation of
ozone (summer smog). The major source of benzene is motor vehicle emissions, which nationally account for 67%
of emissions with other major sources being the extraction and distribution of fossil fuels and certain
industrial processes. Benzene is monitored at a number of sites in Sussex, both at the roadside and in
background locations, using passive diffusion tube monitors. These data indicate that the Government air
quality objective is currently being met at all sites.
Lead has been identified as causing acute and chronic damage to the nervous system, effects on the kidneys,
joints and reproductive system. At extremely high concentrations lead is toxic. There is currently no local
monitoring of lead. Historically, lead was more widely monitored, but concentrations declined dramatically
in the late 1980's, early 1990's due to the introduction of unleaded petrol. Leaded petrol has now been
completely replaced.
Carbon Monoxide affects the body by restricting the uptake of oxygen by carboxyhaemoglobin. At ambient
levels, carbon monoxide may affect concentration, with higher levels leading to more serious nervous system
effects. The major source of carbon monoxide is motor vehicle emissions, which nationally account for 97%
of emissions. Carbon monoxide data from Brighton and Hove show that the Government air quality objective
is currently being met.
Sulphur Dioxide is an acute respiratory irritant. It may also be converted through chemical reactions
in the atmosphere to secondary sulphate particulate matter. Sulphur dioxide is monitored at Lullington
Heath (a rural location), where standards have never been exceeded.
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