SUMMARY

Three different air purifying devices are compared in terms of their influence on indoor air quality. Two systems use ozonisation and ionisation. One system uses ionisation and special filter devices (manufacturer's specifications). In the case of ozone production the perceived intensity and the PD value will increase to inacceptable values. The chemical analyses shows that the increase aldehyde concentration is probably caused by surface reactions between material and ozone. Purifying devices running with ionisation only have slightly no effect on the perceived air quality. Only one test case, when emissions of human beings are an additionally pollution source in the test room, a small increase in air quality can be recognised