Height profile of some air quality markers in the urban atmosphere surrounding a 100 m tower building

Air quality inside buildings, whether naturally or mechanically ventilated, is strongly dependent on that of ambient external air in the surrounding atmosphere. This paper describes results obtained in the assessment of urban air quality influence in the neighbouring of a tall, multistorey building with mechanical ventilation on its indoor air quality. Within the study, which lasted for more than 30 d of continuous monitoring, the concentrations of carbon monoxide (CO), of total and grossly speciated classes of airborne organic vapours and of PM10 airborne particulate were measured both outdoors, at ground and at various heights between street level and the top of the tower building (approximately 100 m) and inside the building. The daily variation of airborne pollutants in the urban atmosphere in the neighbouring of the tower building was traced as the contribution of both time-dependent pollutant production from urban outdoor sources (mainly vehicular traffic) and of the variation of meteoclimatic conditions influencing pollutant diffusion from street level upwards. In particular, a steady concentration decrease with increasing height of the concentration of automotive-related pollutants, such as of PM10 airborne particulate, of a mixture of volatile aromatic compounds (TAAC) and of CO could be measured in the immediate neghbouring of the tower building (values of 40 μg m-3 of PM10 airborne particulate decreasing to 32 μg m-3 at 80 m; of 5 mg of benzene equivalents m-3 at ground level with a 30% decrease at 100 m height; of 3 mg m-3 of CO decreasing to 2.2 mg m-3 at 100 m). The acquired information was employed to advice the building management on the improvement of indoor air quality attainable by moving the air feed grid of the HVAC system to a higher level from ground. An example is reported, which shows the improvement of the indoor air quality in a three-storey peripheral building of the same complex subject to scheduled refurbishing, obtained by moving the HVAC air feed point, originally at +4 m in an internal courtyard, to the building roof, at about +11 m.