Air Quality Health Index

Air Quality Health Index and Bands

Gibraltar has adopted the index and banding system, shown in the table below, since 2005. The system uses a ten-point index (1-10) divided into four bands to provide more detail about air pollution levels in a simple way, similar to the sun index or pollen index:

  • Index 1-3 (Low)
  • Index 4-6 (Moderate)
  • Index 7-9 (High)
  • Index 10 (Very High)

The overall air pollution index for a monitoring location is calculated from the highest concentration of the pollutants measured at that location. The index, bandings and associated concentration ranges for each pollutant are shown in the table:

Band Index Ozone Nitrogen dioxide Sulphur dioxide Carbon Monoxide PM10 Particulate matter
8 hourly or hourly mean Hourly mean 15 minute mean 8 hourly mean 24 hour mean
µg m3 µg m3 µg m3 mg m3 µg m3 
Low 1 0 - 33 0 - 95 0 - 88 0 - 3.8 0 - 21
2 34 - 65 96 - 190 89 - 176 3.9 - 7.6 22 - 42
3 66 - 99 199 - 286 177 - 265 7.7 - 11.5 43 - 64
Moderate 4 100 - 125 287 - 381 266 - 354 11.6 - 13.4 65 - 74
5 126 - 153 382 - 477 355 - 442 13.5 - 15.4 75 - 86
6 154 - 179 478 - 572 443 - 531 15.5 - 17.3 87 - 96
High 7 180 - 239 573 - 635 532 - 708 17.4 - 19.2 97 - 107
8 240 - 299 636 - 700 709 - 886 19.3 - 21.2 108 - 118
9 300 - 359 701 - 763 887 - 1063 21.3 - 23.1 119 - 129
Very High 10 360 or more 764 or more 1064 or more 23.2 or higher 130 or more

Health Advice

Generally if you are young and in a good state of health, moderate air pollution levels are unlikely to have any serious short term effects. However, elevated levels and/or long term exposure to air pollution can lead to more serious symptoms and conditions affecting human health. This mainly affects the respiratory and inflammatory systems, but can also lead to more serious conditions such as heart disease and cancer. People with lung or heart conditions may be more susceptible to the effects of air pollution. Effects on sensitive people can be reduced by spending less time outdoors. 'Reliever' inhalers should lessen effects on asthma sufferers.

The table below shows the types of health effects experienced by the most common pollutants at elevated levels:

Pollutant Health effects at very high levels
Nitrogen Dioxide, Sulphur Dioxide, Ozone These gases irritate the airways of the lungs, increasing the symptoms of those suffering from lung diseases
Particles Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of heart and lung diseases
Carbon Monoxide This gas prevents the uptake of oxygen by the blood. This can lead to a significant reduction in the supply of oxygen to the heart, particularly in people suffering from heart disease

Recommended actions for at risk individuals according to the air quality health index

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 below.