Ultraviolet Radiation on an Urban Street with High-Rise Buildings in Asia

Excessive exposure to UVR is known to cause skin cancer, cataracts, and damage to the DNA1,2. In recent years, many skyscrapers have been built in urban areas, and these buildings use energy conscious glasses such as low-e glass and heat reflecting glass to block heat from the outside. Furthermore, unlike common glass, some high-performance glasses reflect not only infrared radiation but also UVR. Therefore, urban streets flanked with office buildings might induce a condition of high UVR exposure. In this paper, the UVR environment of urban streets with office buildings in Tokyo and Singapore was observed. The amount of UVR exposure at a street block was investigated by determining the radiant quantities of the radiation reflected from four directions using UVR and visible radiation sensors. In the results, UVR correlates roughly with sky view factor. However, the coefficient of variation among UV radiation values for the four directions was lower than that for visible radiation because UVR has a high scattering property3 Therefore, it is important to reduce the doses of UVR on urban streets by implementing strategies such as shielding with plant canopies, shade structures attached to building facades, and grass.