The forecasts are made using NAME, the Met Office's medium-to-long-range
atmospheric dispersion model. It was originally developed as a nuclear
accident model following the Chernobyl incident in 1986, but has since
evolved into an all-purpose dispersion model capable of predicting
the transport, transformation and deposition of a wide class of airborne
materials. NAME is used operationally by the Met Office as an emergency
response model as well as for routine air quality forecasting. Further
applications of NAME include pollution episode analysis and attribution,
scientific research work and commercial applications.
| Interpreting the forecast |
The pollution index or banding
The level of pollution is described either as an index (ranging from
1 to 10) or as a banding (low, moderate, high or very high). These
levels are based on the health effects of each pollutant.
|
Index
|
Banding |
Health effect |
| 1-3 |
LOW |
Effects are unlikely to be noticed even
by individuals who know they are sensitive to air pollutants.
|
| 4-6 |
MODERATE |
Mild effects, unlikely to require action,
may be noticed amongst sensitive individuals.
|
| 7-9 |
HIGH |
Significant effects may be noticed by
sensitive individuals and action to avoid or reduce these
effects may be needed (e.g. reducing exposure by spending
less time in polluted areas outdoors). Asthmatics will
find that their 'reliever' inhaler is likely to reverse
the effects on the lung.
|
| 10 |
VERY HIGH |
The effects on sensitive individuals described
for 'High' levels of pollution may worsen.
|
|
The forecast is produced for a number of different pollutants; typical
health effects and sources are shown in the following tables.
| Pollutant |
Health effects
at very high levels |
|
Nitrogen dioxide
Ozone
Sulphur dioxide
|
These gases irritate the airways of the
lungs, increasing the symptoms of those suffering from
lung diseases.
|
|
Particulates
|
Fine particles can be carried deep into
the lungs where they can cause
inflammation and a worsening of heart and lung diseases.
|
|
| Pollutant |
Sources |
|
Nitrogen dioxide
|
Combustion of fossil fuels, road vehicles
power generation and industrial processes.
|
|
Sulphur dioxide
|
Mostly from burning of fossil fuels.
|
|
Ozone
|
Product of chemical reaction between other
pollutants (Nitrogen oxide and hydrocarbons in the presence
of sunlight).
|
|
Particulates
|
Combustion processes, especially diesel
exhausts, and natural sources such as dust.
|
|
Some of these local air quality forecasts also include a forecast
of the UV Index, a measure of the strength of the sun's ultraviolet
(UV) radiation. A UK-wide forecast,
and real-time UV levels, are available, as well as information
to help interpret the risks to particular skin types.
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We currently provide the following organisations with an air quality
forecast service.
For further information about working with the Met Office on weather
solutions please contact our 24-hour Customer
Centre.
