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Daily Air Quality Index

How to use the Daily Air Quality Index

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 provided on the Additional information on the short-term 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 forcast for North Wales and South Wales.
Step 3: Use the health messages corresponding to the highest forecast level of pollution as a guide.

Air pollution bands and indices µg/m³

Pollutants Band Low Moderate High Very High
Index 1 2 3 4 5 6 7 8 9 10
Ozone - running 8 hourly mean µg/m³ 0-33 34-66 67-100 101-120 121-140 141-160 161-187 188-213 214-240 241 or more
Nitrogen Dioxide - hourly mean µg/m³ 0-67 68-134 135-200 201-267 268-334 335-400 401-467 468-534 535-600 601 or more
Sulphur Dioxide - 15-minute mean µg/m³ 0-88 89-177 178-266 267-354 355-443 444-532 533-710 711-887 888-1064 1065 or more
PM2.5 Particles - 24 hour running mean µg/m³ 0-11 12-23 24-35 36-41 42-47 48-53 54-58 59-64 65-70 71 or more
PM10 Particles - 24 hour running mean µg/m³ 0-16 17-33 34-50 51-58 59-66 67-75 76-83 84-91 92-100 101 or more

A health descriptor is associated with each band based upon current understanding and research studies (Department of Health). Current descriptors are presented below.

Air pollution bandings and health descriptor impacts on sensitive receptors
Air Pollution Banding Value Accompanying health messages for at-risk groups and the general population
At-risk individuals* General Population
Low 1-3 Enjoy your usual outdoor activities. Enjoy your usual outdoor activities.
Moderate 4-6 Adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors. Enjoy your usual outdoor activities.
High 7-9 Adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High 10 Adults and children with lung problems, adults with heart problems, and older people, should avoid strenuous physical activity. People with asthma may find they need to use their reliever inhaler more often. Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

*Adults and children with heart or lung problems are at greater risk of symptoms. Follow your doctor´s usual advice about exercising and managing your condition. It is possible that very sensitive individuals may experience health effects even on Low air pollution days. Anyone experiencing symptoms should follow the guidance provided on the Additional Information on the Short-term Effects of Air Pollution page.