Indoor air quality (IAQ) can be characterised by physical parameters (e.g., temperature, relative humidity, air exchange rate), chemical air pollutants (e.g., carbon dioxide, nitrogen dioxide, particulate matter, ozone, benzene, etc.) and biological agents (e.g., pollen, fungi). During the monitoring campaign 64 primary school buildings were investigated in Central Europe (Czech Republic, Hungary, Italy, Poland and Slovenia) where the concentration of the most important air pollutants as well as the physical parameters were monitored. Due to the complexity of this issue, a simple Indoor Health Index has been developed (i) to disseminate the results of the project among the public and stakeholders and (ii) to provide health relevant information about the IAQ.
The calculation of the Indoor Health Index is based different threshold values determined by the health effects of the air pollutants/physical parameters (recommendations of the WHO and/or EC and/or scientific papers).
We applied a five scale categorization of the most important and frequent chemical air pollutants using for the cut off points.
Table 1. The calculation of Indoor Health Index.
| Category | benzene (µg/m3) | formaldehyde (µg/m3) | PM2.5 (µg/m3) |
|---|---|---|---|
| Healthy | <1.7 | <10 | <10 |
| Moderate | 1.7-4.99 | 10-19.9 | 10-24.9 |
| Unhealthy | 5-7.5 | 20-50 | 25-49.9 |
| Very unhealthy | 7.51-10 | 51-100 | 50-75 |
| Dangerous | >10 | >100 | >75 |
When applying the index in practice we characterize the actual air quality according to the worst category, indicating the pollutant.
The database in which the Indoor Health Index has been calculated is available upon request.
To characterize the thermal comfort, different cut-off points for two physical parameters, temperature and relative humidity, as well as for the concentration of carbon dioxide have been set (Table 2).
Table 2: Categories based on the measured temperature, relative humidity and carbon dioxide concentration values
| Category | RH (%) | T (°C) | CO2 (ppm) |
|---|---|---|---|
| healthy | 43 < RH < 67 | 18.5 < T < 25.5 | <1200 |
| moderate | 37 < RH < 43 67 < RH < 73 | 17.5 < T < 18.5 | 1200-1800 |
| unhealthy | RH < 37 RH > 73 | T < 17.5 T > 25.5 | >1800 |
