If the source is known, carbon monoxide can be used as an indicator of several pollutants in particulate and gaseous form from this source.
As the fuel burns, carbon monoxide enters the room air, binds to blood hemoglobin and reduces the oxygen - carrying capacity of the blood, an effect especially harmful to individuals with heart and lung diseases. Our study showed that the average particulate level is 40 mg.m-3 in home without smokers. Smokers raised particulate levels in some cases over ten times and it is level not allowed by air quality standards. Concentrations of indoor air CO pollutants fall after combustion sources are turned off, of course, but it may take several hours before normal levels are reached in conventional, poorly sealed homes. In well - sealed, energy efficient homes it could take much longer. If several lengthy meals are cooked during a day, exposure to these pollutants can be quite high. Typical situation when carbon monoxide level drops after the stove is turned off is in figure 3. As it can be seen, the concentration level in the kitchen is similar to the other rooms in the same flat. Concentration levels are trapped in various spaces of the flat also for the reason that the flat area is small.

Figure 3. Drop in carbon monoxide level in homes after the stove is turned off



Sulfur Dioxide
At present time, sulfur dioxide is not the significant indoor chemical pollutant but still has it's important position from outdoor air quality point of view. Outdoor sulfur dioxide pollution level is low and annual average concentrations in individual locations fluctuates within the range of 8 - 27 µg.m-3. Sulphur dioxide pollution is of seasonal course, reaching the maximum concentrations in winter. Regarding the prevailing wind directions, the industrial center of East Slovakia - Kosice, which results are presented, is favourably situated to the major sulphur dioxide emission sources. Sulfur dioxide concentrations were considerably lower as compared with those in the previous year. Under the air circulation, occurring in less than 5 % of cases within a year, the average sulphur dioxide concentration of about 50 µg.m-3 was achieved. In the whole, sulfur dioxide air pollution level ranged far below the ambient air quality standards. Our interest has been concentrated also to indoor concentrations of SO2 and its outdoor dependencies which are shown in the figure 4. The indoor level concentrations of sulphur dioxide change within the range of 5 - 17 g.m-3. Indoor sulfur oxides are comparatively rapidly decreased by so called “wall effect“, they are absorbed by lime plaster and their concentration goes down fast even if the room is ventilated by infiltration only. The concentration of sulfur dioxide is difficult to measure by one hour after closing the windows.