The SINPHONIE project (Schools Indoor Pollution and Health: Observatory Network in Europe), which is referred to in the report, recommend that a lot of measures needs be taken in order to get a good environment for education. Good indoor air quality is the basis of lower rates of absenteeism among children and teachers, stronger academic performance, better teacher retention and job satisfaction, cost savings in many areas including building maintenance and less sick leave.
Very few countries have legally stated what levels of CO₂ should be obeyed but more and more countries have taken actions in the right direction, many of which whom have done so as a result of the questioner made by the WHO.
Out of the 31 countries questioned 37% had some laws or recommendations of allowed levels of ventilation or CO₂. Only 7% wanted these levels to be constantly monitored. The maximum allowed ppm (parts per million) levels ranged from 1000 to 5000 ppm. These numbers can be compared to temperature recommendations (and laws) which 76% of the countries had in place.
Within the field of the report 20 schools from different countries where monitored for a period and the outcome of this screening was that in some schools the students were exposed for CO₂ levels over 1000 ppm for 90-95% of the time spent in the class room whereas other schools this number was 30-45% of the time. Levels above 2500 ppm was found in some schools to be exceeded during 50-55% of a school day. Actions lower these numbers, such as force ventilation during breaks or mechanical fans in the ventilation system, was not being used - mainly because of poor heating, i.e. forcing fresh air into the building would lower the indoor air temperature too much.
In the context of this report it is easy to understand that the indoor air quality, not only at schools but also domestic homes, largely dependent on ventilation and heating. Today the countries that do have recommendations mainly use the indirect measure of ventilation rate whereas the use of real temperature, humidity, carbon dioxide and particle matter would be a better direct indication of air quality.