What is the Air Quality Index for Health?

The Environmental Protection Agency's Air Quality Index for Health (AQIH) is a number from one to 10 that tells you what the air quality currently is in the station nearest you and whether or not this might affect  the health of you or your child. A reading of 10 means the air quality is very poor and a reading of one to three inclusive means that the air quality is good. The AQIH map updates every two to five minutes with the most up-to-date calculated Air Quality Index for Health (AQIH) for each station.


Using the AQIH can help you better protect the health of you or your child, particularly if either of you are very sensitive to air pollution.


This section gives you information on :

·       how you use the AQIH,

·       the short-term health effects of air pollution,

·       health advice messages to follow when using the AQIH, and

·       how we work out (calculate) the AQIH.


How do I use the Air Quality Index for Health (AQIH)?

Step 1: Read ‘What are the short-term effects of air pollution?’  to see if you or your child is likely to be at risk from air pollution. Your doctor may also be able to advise you.

Step 2: Figure out which Air monitoring station is nearest to you using the map, or which one best represents air quality where you are. Check the AQIH at that station if you think you are at risk, and are planning strenuous outdoor activity.

Step 3: Read the health advice messages for the current AQIH for your region.

Disclaimer: In some circumstances, due to site-specific conditions, the AQIH may give a an incorrect reading. The EPA is not liable for any consequences from decisions made based on this index. If a pollutant in the AQIH displays no colour (grey), there may be an instrument or communication issue associated with that instrument.

Step 1: What are the short-term effects of air pollution?

Air pollution has a range of effects on health. However, air pollution in Ireland does not, in general, rise to levels at which people need to make major changes to their habits to avoid exposure; nobody need fear going outdoors.


Below, we list the main short-term effects of air pollution on health for different groups of people at different bands of the AQIH. The bands are:

  • Good Air Quality, 
  • Fair Air Quality,
  •  Poor Air Quality, 
  • Very Poor Air Quality 

Adults and children with heart or lung conditions including asthma 

If you or your children suffer from a heart or lung condition, you are more likely to become ill and need treatment but only a small number of you are likely to be affected. It is not possible to predict in advance who will be affected. If you are very sensitive to air pollution, you may experience health effects even on days with good air quality (reading of 1-3 on the AQIH).

If you are asthmatic you may notice that you need to increase your use of inhaled reliever medication on days when air pollution is fair, poor or very poor.

Children need not be kept from school or prevented from taking part in games. If your child has asthma, they may need to use their reliever medication on days when levels of air pollution are higher than average.


Older People

Older people are more likely to suffer from heart and lung conditions than younger people. So if you are older it makes sense to be aware of current air quality in the station nearest to you and to follow the appropriate health advice messages.


General population

At very poor levels of air quality (reading 10 on the AQIH), some of us, even if we are healthy, may get

  • a sore or dry throat,
  • sore eyes or,
  • in some cases, a tickly cough.

Step 2: What is the Air Quality in your region?

If you think you may be at risk, and are planning strenuous activity outdoors such as sports, check the AQIH for the station nearest you on the map.

You can also check a station in a  similar sized town. Any location may have local conditions which give rise to specific air quality issues; however, in many circumstances the conditions in one town may be representative of those in another of similar size and/or geographical location.

Blue dots represent non automatic stations that do not present real-time information.

Step 3: What are the AQIH health advice messages?

The AQIH health advice messages are messages to help you and your family better manage your health. The table below gives health messages for individuals who are sensitive to air pollution (at risk) and for the general population.

AQIH with health advice. Colours changed to make it easier to read ‌‎‌

 * If you or child has heart or lung problems you are at greater risk of symptoms from air pollution. You need to follow your doctor's usual advice about exercising and managing your condition. If you are very sensitive, you may have health effects even on days when the air quality is good. Anyone experiencing symptoms should follow the guidance provided in the section on 'What can I do when there are increased levels of air pollution?'.


What can I do when there are increased levels of air pollution?

If you have noticed that you are usually affected by increased levels of air pollution, you can go out when levels of air pollution increase but you might reduce the amount of exercise you do outdoors.


Older people and those with heart and lung conditions might avoid physical exertion on days with poor or very poor air quality (7-10 ratings).


Adults and children with asthma should make sure that you are taking your medication correctly. If you are unsure, ask your health care practitioner (your local doctor or pharmacist). You may notice that you have to use your inhaled reliever medication more.


Adults with heart and circulatory conditions should not change your treatment schedules on the basis of advice provided by the AQIH. You should seek advice from your health care practitioner (your local doctor or pharmacist) if you need to.


Some athletes, even if you are not asthmatic, may find you are not performing as well as you expect when levels of a certain air pollutant (ground-level ozone) cause poor or very poor air quality (readings 7-10 on the AQIH).

You may notice that when you breathe deeply you feel some discomfort in your chest. This does not mean you are in any danger but it may be better if you do less exercise on these days. Please get medical advice if you have any concerns.

In Ireland, levels of ground-level ozone rarely reach poor or very poor (readings 7-10 on the AQIH).

How we work out (calculate) the AQIH

The Air Quality Index for Health (AQIH) has 10 points ranging from 1 to 10. These points are divided into four coloured bands – good (readings of 1-3), fair (readings of 4-6), poor (7-9) and very poor (10). The higher the number the worse the quality of the air.  For example, a AQIH reading of 10 means that the air quality is very poor and a reading of 1, 2 or 3 means that the air quality is good (see table below).

The AQIH is based on measurements of five air pollutants all of which can harm health. The five pollutants are: 

    • Ozone gas
    • Nitrogen dioxide gas
    • Sulphur dioxide gas
    • PM2.5 particles and
    • PM10 particles 

We use automatic air quality monitors to measure how much pollutant there is (we work this out per each cubic metre – m3) per hour.

The pollutants measured at each station vary. All five pollutants are not measured at each site. Most monitoring stations measure particulate matter as these present the greatest health risk. Nitrogen dioxide is monitored mainly in urban areas with significant exposure to vehicle emissions.

For each monitoring station, we work out the index number for each pollutant separately. The overall  AQIH is the highest available pollutant index. For example, if the ozone index figure is greater than sulphur dioxide, we give the higher ozone index as the overall AQIH. The table below shows the ranges of concentration (amounts) for each pollutant. Examples of how to calculate the AQIH are given below the table.  

  Air Quality Index for Health Bands

 Example 1

Pollutant Measurement in 


Ozone 80 3
Nitrogen Dioxide 35 1
Sulphur Dioxide 10 1
PM 2.5 Particles 45 5
PM 10 Particles 71 6


The AQIH is 6 - Fair


Example 2

Pollutant Measurement in 


Sulphur Dioxide 10 1
PM 2.5 Particles 25 3
PM 10 Particles 50 3

The AQIH is 3 - Good


AQIH Region Layer

As well as viewing the AQIH for the station closest to your home you can select to view the AQIH for your region on the map. If you are close to the border of another AQIH region you can check the AQIH for that region also. The tab to turn on the region layer is on the top right hand side of the map.

The status of the AQIH regions is linked to the @epaairquality twitter account. If air quality goes to a fair or worse status at any station in a region, the regional AQIH will reflect the status of that station. To view the AQIH in your local area you should then view the AQIH at the station closest to your home. The current AQIH regions are: