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 ventil ated, is strongly dependent on that of ambient external air in the sur rounding atmosphere. This paper describes results obtained in the asse ssment of urban air quality influence in the neighbouring of a tall, m ultistorey building with mechanical ventilation on its indoor air qual ity. Within the study, which lasted for more than 30 of continuous mon itoring, the concentrations of carbon monoxide (CO), of total and gros sly speciated classes of airborne organic vapours and of PM10 airborne particulate were measured both outdoors, at ground and at various hei ghts between street level and the top of the tower building (approxima tely 100 m) and inside the building. The daily variation of airborne p ollutants in the urban atmosphere in the neighbouring of the tower bui lding was traced as the contribution of both time-dependent pollutant production from urban outdoor sources (mainly vehicular traffic) and o f the variation of meteoclimatic conditions influencing pollutant diff usion from street level upwards. In particular, a steady concentration decrease with increasing height of the concentration of automotive-re lated pollutants, such as of PM10 airborne particulate, of a mixture o f volatile aromatic compounds (TAAC) and of CO could be measured in th e immediate neghbouring of the tower building (values of 40 mu gm(-3) of PM10 airborne particulate decreasing to 32 mu gm(-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 mgm(-3) of CO decreasing to 2.2 mgm(-3) at 100 m). The acquired information was employed to advice the building manageme nt on the improvement of indoor air quality attainable by moving the a ir feed grid of the HVAC system to a higher level from ground. An exam ple 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, or iginally at + 4m in an internal courtyard, to the building roof, at ab out + 11m. (C) 1998 Elsevier Science Ltd. All rights reserved.