Daily Pollution Level Bands The Daily Air Pollution levels at the top of our homepage uses 4 'bands' to describe levels of pollution. The bands are as follows: - LOW, MODERATE, HIGH AND VERY HIGH Healthy people do not normally notice any effects from air pollution, except occasionally when air pollution is 'very high'. The table below shows the four bands and their impact on the health of people who are sensitive to air pollution. The changes from band to band do not represent sudden steps. The effects of air pollutants on health increase gradually as air pollution levels rise. Pollution Band Health Impact LOW Effects are unlikely to be noticed, even by people who know they are sensitive to air pollutants MODERATE Mild effects are unlikely to require action, but may be noticed by sensitive people HIGH Sensitive people may notice significant effects, and may have to take action to reduce or avoid them (for example, by reducing time spent outdoors). Asthmatics will find that their 'reliever' inhaler is likely to reverse the effects of pollution on their lungs VERY HIGH The effects on sensitive people, described for 'high' levels of pollution, may worsen Sensitive individuals are those people who suffer from heart and lung diseases, including asthma, particularly if they are elderly. It is important to look at the bands in the light of personal experience. Individual people - especially those who are sensitive to pollution - will learn from experience how air pollution affects them. Effects may still be noticed for some days after pollution levels have fallen to low or moderate levels.   People with heart conditions or severe lung diseases (e.g. chronic bronchitis or emphysema) may 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.  This Information Service only provides information about the short-term health effects of certain air pollutants. Air pollution is likely to have an effect on health over the longer term, but at the moment we do not fully understand these effects.