For the ten years following 1965, Tokyo's air was polluted mainly by the smoke from factories. This air pollution was remarkably improved by carrying out countermeasures against fixed emission sources, such as strict control of air pollutant sources, including boilers, and use of higher quality fuel.
Subsequently, the Environmental Quality Standards regarding nitrogen dioxide and suspended particulate matter were not sufficiently met and this unfortunately continued mainly because of steadily increasing automobile traffic and the fumes emitted by diesel-powered vehicles. In October 2003, ahead of the Japanese Government, Tokyo Metropolitan Government (TMG) started to restrict diesel-powered vehicles in collaboration with the eight local governments in the Kanto district. Since then, concentrations of suspended particulate matter have been significantly improved and related Environmental Quality Standards have almost been met. Thus, the atmospheric environment in Tokyo has been steadily improving over recent years.
However, measures to cope with photochemical oxidants and air-pollution controls in effect in the coastal areas of Tokyo Bay are just some of the outstanding issues at play.
In order to realize the cleanest air among the world's largest cities, we will fortify actions to deal with such issues and otherwise strive to respond to these new challenges,such as measures to cope with fine particulate matter (PM 2.5).