One of the concepts of the ventilation rate control in buildings with dense and unpredictable occupancies is based on the CO2 measurements. There are many limitations regarding the validity of CO2 measurement inputs as suitable to the ventilation rate control. Verifying research has been conducted in an air-conditioned auditorium, in the real conditions at altered ventilation air thermal parameters and variable occupancy. The CO2 and the number concentrations of the fine and coarse aerosol particles(> 0.3 μm) and bioaerosol particles (bacteria and staphylococci) as well as the indoor air thermal parameters were measured in the individual sectors of the occupied area. The sensory assessments and instrumental determinations of the acceptability of indoor air quality (ACC) were also performed. The ventilation control strategy based, apart from the CO2 measurements, on the continuous monitoring of the perceived air quality (PAQ) in the auditorium sectors has been suggested. The PAQ monitoring could be accomplished by aerosol concentration measurements and the ACC instrumental determinations. This strategy should ensure a desired PAQ in sectors which benefit the occupants' comfort, health and productivity as well as energy savings not only in the case of its implementation in the considered auditorium.

Simultaneous measurements of the indoor and outdoor particle mass (PM) and particle number (PN) concentrations as well as the air temperature, relative humidity (RH), and CO2 concentrations have been conducted in 6 occupied (L) and unoccupied (V) classrooms in 3 secondary schools in Lublin, Poland, in the heating (H) and summer (S) seasons. The schools were located in residential areas where the majority of private houses are heated by means of coal-burning stoves. The ratios of the average particle concentrations in occupied and unoccupied classrooms (L/V) were higher during the heating season measurements. The ratios of the average particle concentrations during the measurements in the heating and summer seasons (H/S) were higher in occupied classrooms. In both seasons the average PM and PN concentrations amounted to 239 μg/m3 and 7.4×103/cm3 in the occupied classrooms, and to 76 μg/m3 and 5.4×103/cm3 in the unoccupied classrooms, respectively. The particle exposures experienced by students were higher in the monitored classrooms than outdoors and were on average about 50% higher in the heating than in the summer season. A positive correlation between mass concentrations of coarse particles and indoor air temperature, RH and CO2 concentrations in both seasons was observed. The concentrations of fine particles were negatively correlated with the indoor air parameters in the heating season, and positively correlated in the summer season.