Correlation of indoor-outdoor air quality in urban areas

Indoor and outdoor air quality was investigated at 28 public locations with mostly mechanical ventilation systems. The locations were selected from various geographic categories representing different environments for indoor/outdoor air pollutant characterisation. The selected indoor locations included restaurants, recreation places, sport centres, schools, commercial kitchens, hotels, swimming pools and movie theatres. The concentrations of PM, CO, NO2 and selected priority metals were measured at each location. Pollutant concentrations exceeded indoor air quality standards at locations with indoor sources (smoking, gas stoves, cleaning products, etc.). As such, highest I/O ratios were correlated with the existence of indoor sources for the pollutant of concern. The effects of outdoor conditions were reflected in terms of distance to the main road and the correlation between indoor and outdoor levels was evident when the sampled locations were sorted on the basis of their source characteristics.