Daily Air Quality Index (DAQI) is used to communicate information about real-time and forecast levels of outdoor air pollution in the short term. It also provides health advice in the form of recommended actions you may wish to take, according to the level of air pollution. The system was recommended by the Committee on Medical Effects of Air Pollutants and is intended to help people plan ahead and take action to reduce the health effects of air pollution, where relevant.
The index is numbered 1-10 and divided into four bands to provide detail about air pollution levels in a simple way. The bandings are colour coded for ease of interpretation.
- low pollution (levels 1, 2 and 3)
- moderate pollution (levels 4, 5 and 6)
- high pollution (levels 7, 8 and 9)
- very high pollution (level 10)
Each band of the DAQI (low, moderate, high and very high pollution) comes with health advice for:
- the general public
- adults and children with heart or lung conditions, and older people, as these groups may be more susceptible to the health effects of air pollution
The index is based on concentrations (measured in micrograms per cubic meter (µg/m3) of 5 pollutants:
- nitrogen dioxide (NO2)
- particles less than 2.5 µm (PM2.5)
- particles less than 10 µm (PM10)
- sulphur Dioxide (SO2)
- ozone (O3).
Each pollutant has its own set of concentration boundaries that determine the DAQI level.
The DAQI score for a specific location is based on the highest measured or predicted level out of these pollutants.
Boundaries Between Index Points for Each Pollutant
Use the tabs below to view the bandings for each pollutant.
Ozone
Based on the running 8-hourly mean.
| Index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Band | Low | Low | Low | Moderate | Moderate | Moderate | High | High | High | Very High |
| µg/m-3 | 0-33 | 34-66 | 67-100 | 101-120 | 121-140 | 141-160 | 161-187 | 188-213 | 214-240 | 241 or more |
Nitrogen Dioxide
Based on the hourly mean concentration.
| Index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Band | Low | Low | Low | Moderate | Moderate | Moderate | High | High | High | Very High |
| 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
Based on the 15-minute mean concentration.
| Index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Band | Low | Low | Low | Moderate | Moderate | Moderate | High | High | High | Very High |
| µg/m3 | 0-88 | 89-177 | 178-266 | 267-354 | 355-443 | 444-532 | 533-710 | 722-887 | 888- 1064 |
1065 or more |
PM2.5 Particles
Based on the daily mean concentration for historical data, latest 24 hour running mean for the current day.
| Index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Band | Low | Low | Low | Moderate | Moderate | Moderate | High | High | High | Very High |
| 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
Based on the daily mean concentration for historical data, latest 24 hour running mean for the current day.
| Index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Band | Low | Low | Low | Moderate | Moderate | Moderate | High | High | High | Very High |
| µg/m3 | 0-16 | 17-33 | 34-50 | 51-58 | 59-66 | 67-75 | 76-83 | 84-91 | 91-100 | 101 or more |
Health advice for the DAQI
Health advice for low levels of air pollution
For most people, short term exposure to low levels of air pollution is not a significant issue. Continue your usual outdoor activities.
Some people might experience symptoms due to air pollution, even when levels are low.
Adults and children with lung or heart conditions are at greater risk of experiencing symptoms.
Symptoms include:
- coughing
- chest tightness and pain
- difficulty breathing
- worsening of asthma symptoms
- worsening of heat-related symptoms, such as heart palpitations
- worsening of chronic obstructive pulmonary disease (COPD) symptoms
Symptoms could start within hours or several days after exposure to air pollution.
Follow your doctor or nurse's usual advice about physically demanding activities and managing your condition.
Follow your agreed management plan if you have one – for example, an asthma action plan. Ask your doctor or nurse for a plan if you do not have one.
Also consider the impact of other triggers on your symptoms – for example, high pollen outside or poor air quality indoors.
Health advice for moderate levels of air pollution
For most people, short term exposure to moderate levels of air pollution is not a significant issue. Continue your usual outdoor activities. However, if you are experiencing symptoms, try to reduce your exposure to air pollution.
Speak to your doctor or nurse if:
- you have new symptoms
- your symptoms get worse
- your symptoms do not get better after a week
Also consider the impact of other triggers on your symptoms – for example, high pollen outside or poor air quality indoors.
Advice for adults and children with lung or heart conditions
Try to adapt physically demanding activities outdoors, especially if your symptoms get worse.
Follow your agreed management plan if you have one – for example, an asthma action plan. Ask your doctor or nurse for a plan if you do not have one.
Health advice for high and very high levels of air pollution
Try to reduce your exposure to air pollution, especially if you’re experiencing symptoms.
Speak to your doctor or nurse if:
- you have new symptoms
- your symptoms get worse
- your symptoms do not get better after a week
Also consider the impact of other triggers on your symptoms – for example, high pollen outside or poor air quality indoors.
Advice for adults and children with lung or heart conditions, and older people
You should adapt physically demanding activities outdoors, especially if your symptoms get worse.
Follow your agreed management plan if you have one – for example, an asthma action plan. Ask your doctor or nurse for a plan if you do not have one.
How you can reduce your exposure to air pollution
Long term exposure to air pollution (over years) can lead to many different different health conditions and can reduce life expectancy.
You should try to reduce your exposure to air pollution where you can, even when levels are low.
Consider the following actions:
- take routes where there is less traffic, especially at busy times of day when you can
- commute, walk or exercise in parks or other green spaces, if you are not affected by pollen
- if you exercise indoors, make sure the room is well ventilated
Get more advice on actions you can take to reduce your exposure to air pollution.
Read further information on how outdoor pollution can impact health on NHS Inform and the PHS webpages.