What do the air quality bands mean?
In the UK, most air pollution information services use the index and banding system approved
by the Committee on Medical Effects of Air Pollutants (COMEAP). This index is designed to
advise about short
term health effects only. Because of this, it is possible for a pollutant at a site to have a low
short term index every day and yet fail an
air quality standard
which is based on long term health effects.
The index has four bands indicating the degree of air pollution and the health risk. These are calcualted for each pollutant and then the
highest band is used to indicate overal air pollution. Sometimes air pollution can be worse in the suburbs than in locations close to
roads. This is mainly due to differences in ozone concentrations. Although traffic pollution contributes to ozone formation, fresh vehicle
exhaust reacts to consume ozone locally.
To use the index follow the following three steps:
- Step 1. Determine whether you (or your children) are likely to be at-risk from air pollution. Information on groups who may be affected is on
the ‘Additional information on the effects of air pollution’ page. Your doctor may also be able to give you advice.
- Step 2. If you may be at-risk, and are planning strenuous activity outdoors, check the air pollution forecast.
- Step 3. Use the health messages corresponding to the highest forecast level of pollution as a guide.