Air quality health index (AQHI)

The aim of the development of an air quality index is to inform non-professionals about the ambient air quality and related health effects.
The Air quality health index (AQHI) is particularly suitable for this purpose because is scientifically well-based but easy to calculate and to understand by non-professionals.
The AQHI has two main components, the concentration ranges of air pollutants and the cumulative health effect categories (table 1.). The AQHI is based on one-hour daily maximum values of basic air pollutants, including sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3) and on daily 24 hour mean of particulate matter (PM 10).  
The AQHI should be calculated daily. If the concentration of every pollutant is in the 1st range, the evaluation based on AQHI is “1 – acceptable”. If the concentration of any pollutant is in the 2nd range, the AQHI becomes “2 – with concern”, if the concentration of any pollutant is in the 3rd range, the AQHI becomes “3 – unhealthy” and if the concentration of any pollutant is in the 4th range, the AQHI becomes “4 – dangerous”.

Air Quality
Health Index

Daily air pollution µg/m3
1 hour max
1 hour max
1 hour max
1 hour max
24 hour mean
0-249 0-99 0-9999 >0-119 0-49
with concern
250-399 100-349 10000-19999 120-179 50-74
400-499 350-399 20000-29999 180-239 75-99
>500 >400 >30000 >240 >100
Table 1.: table to calculation of air quality health index


Based on scientific data the health effect can be assigned to concentration ranges of air pollutants (table 2.)

Air Quality
Health Index
Acute health effects

acceptable air quality, acceptable risk

With concern

Measures are not required, moderate health effects
can be observed in sensitive population


Significant health effects in sensitive populations, individual
protection is required to reduce adverse health effects


Significant health effects in the whole population,
measures of the authorities are required

Table 2.: Acute health effects in different AQHI categories

How to consult the virtual observatory
As soon as opens the page the user can see a map of the cooperation area. Then is required to select a date on the upper part of the page in order to visualize the index value for each partner cities. This is graphically represented by a flag of the corresponding colour for each value.
Clicking on each flag you can see also the numerical index value and the related locality.