Thermal Comfort indexes express the satisfaction or not, of the individual from the environment and the prevailing conditions. They represent a very good estimate of the prevailing conditions and are specially useful to sensitive groups of people like elderly, children, persons with respiratory problems e.g. asthma, athletes, people working outdoors and in general to groups of people whose work is directly influenced by the meteorological conditions. The directly depend upon
- the temperature, humidity, wind speed and relative cloud coverage (these are downloaded automatically in real time from the existing private meteorological stations operating all over Greece and have their data in the internet),
- the radiant temperature (is calculated from the solar radiation, which in turn is calculated for the specific place and time), and
- the clothing and the person's metabolism in relation to his/her activities (are entered by the user).

Two indexes are calculated in www.airquality.gr for the whole of Greece:
The Discomfort Index, DI
Personal Mean Vote, PMV