INVESTIGATION OF OUTDOOR AIR QUALITY ABOVE TOKYO FOR NATURAL VENTILATION OF TALL BUILDINGS

Air Quality at the height of skyscraper has not almost been cleared yet. Upper part of dwellings of tallbuildings at down town might intake inadequate outdoor air. The object of this research is to make clearof characteristics of outdoor air above down town of Tokyo and provide habitants information about badtiming for natural ventilation.Air qualities data acquisitioned at the height of 25m, 125m and 225m at Tokyo Tower provided byBureau of Environment, Tokyo Metropolitan Government have been analyzed in these several years.As the result, tendencies were indicated in 2005 that were essentially the same as in the past severalyears. That is, the concentration of nitrogen dioxide (NO2) was highest at 25m, exceeding theenvironmental standards by 4-10%. It furthermore increased when there was wind from the south.The need for caution is greatest at 10:00-23:00 in November. In the case of photochemical oxidants(OX), the concentration was highest at 225m and, unlike NO2, the ratio of values exceeding thestandards increase along with the increase in height. The values were most readily exceeded whenthere was wind from the south and caution is required during the hours of 11:00-20:00 in April-August.The Keihin Industrial Area and a high-speed expressway network are located in the SE direction fromthe Tokyo Tower and they possibly exert an effect.