An experimental study of the indoor air quality in areas of different use

The purpose of the present work was to study experimentally the indoor air quality status
regarding PM10, PM2.5, TVOCs, CO2, NOx, SO2 and O3 in selected differently used areas. A
flat on the third floor of a multi-storey building, located at a suburban area north-east of the
centre of Athens and close to a heavily trafficked road and two offices of the Environmental
Physics Department building at the University campus, in a suburban area were selected for
the purpose of the measurements. The experimental campaigns covered several days in
each area in order to include different indoor conditions and outdoor concentration levels.
Total VOCs and CO2 were measured on a continuous basis at selected locations only in the
indoor environment with two sets of portable samplers. Indoor and outdoor NOx, SO2 and O3
were measured with analysers. PM10 and PM2.5 24 hour averaged measurements were taken
with the aid of two sets of indoor particle samplers.
Experimental results obtained from Offices 1 and 2 indicate that the indoor air quality in both
offices is satisfactory with respect to NOx, SO2 and O3. PM10 concentrations are well above
the specified limits on days of smoking or closure of windows in both offices. The indoor air
quality in Office 1 seems satisfactory with respect to CO2 and total VOCs concentrations
measured, even on days when smoking was taking place and windows were kept closed
while all occupants were present. In Office 2, both CO2 and total VOCs concentrations are
elevated, even on days when the windows were open or smoking was not taking place, but do
not exceed the specified limits, indicating poor air renewal.
Experimental data obtained from the residence indicate firstly that NOx, SO2 and O3
concentrations in the indoor environment depend directly on the outdoor levels as they
presented the same diurnal variation, while the indoor values were lower than the outdoor
ones. Surprisingly enough, the total VOCs concentrations in the living room presented high
values when windows were kept open indicating strong presence of outdoor sources.
Furthermore, activities such as cooking, cleaning, smoking and use of indoor air fresheners
further increased the total VOCs levels. Regarding CO2 concentrations, they were almost
constant indicating acceptable but not satisfactory renewal of the indoor air. Finally, PM10
concentration measurements were most of the time below the specified limits, with some
exceptions mainly related to window opening and cooking.