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).
In addition, we will pursue actions to dispel the concerns of the residents of Tokyo, such as by reinforcing and thoroughly implementing measures to prevent the dispersal of asbestos during the demolition of buildings.
The representative pollutants that contaminate the air and present a danger to public health include nitrogen dioxide, suspended particulate matter, photochemical oxidants, sulfur dioxide, and carbon monoxide. The Environmental Quality Standards regarding these pollutants have been established as administrative goals. (See page 71.) TMG has made efforts to meet the Environmental Quality Standards regarding these substances in order to improve air pollution, protec residents’ health, and ensure their safety. TMG also established monitoring stations in various places in Tokyo and the conditions of air pollution are monitored over a 24-hour period. (See page 72.)
According to data obtained in fiscal year 2006, the concentrations of nitrogen dioxide measured at all 43 general air pollution monitoring stations met the Environmental Quality Standards. In contrast, attainment was confirmed at 21 out of 34 roadside air pollution monitoring stations in the same year.
The achievement of the Environmental Quality Standards regarding suspended particulate matter has been confirmed at all 47 general air pollution monitoring stations and all 34 roadside air pollution monitoring stations for the first time since monitoring began.
On the other hand, according to annual average data, the concentration of nitrogen dioxide has remained flat, while that of suspended particulate matter has shown a downward trend over recent years. This decreasing tendency has been clearly observed since 2003.
The Environmental Quality Standards regarding carbon monoxide and sulfur dioxide has been fulfilled at all monitoring stations; however, the standards regarding photochemical oxidants have not yet been met at any of the stations.
Conditions of Achievement of Environmental Quality Standards regarding Air Pollutants in Fiscal 2006
| Names of Substance | Achievement of Environmental Quality Standards |
|---|---|
| Nitrogen dioxide (NO2) | Achievement of the Environmental Quality Standards regarding NO2 has been confirmed at all 43 general air pollution monitoring stations (general stations), while their achievement has been confirmed at 21 of 34 roadside air pollution monitoring stations (roadside stations). |
| Suspended particulate matter (SPM) | Achievement of the Environmental Quality Standards regarding to SPM has been confirmed at 45 out of 46 general stations and all 34 roadside stations. |
| Photochemical oxidants (Ox) | Achievement of the Environmental Quality Standards regarding Ox has not been all 40 general stations. |
| Sulfur dioxide (SO2) | Achievement of the Environmental Quality Standards regarding SO2 has been confirmed at all the monitoring stations. |
| Carbon monoxide (CO) | Achievement of the Environmental Quality Standards regarding CO has been confirmed at all the monitoring stations. |
| Benzene | Achievement of the Environmental Quality Standards regarding benzene has been confirmed at all the monitoring stations. |
| Trichloroethylene | Achievement of the Environmental Quality Standards regarding trichloroethylene has been confirmed at all the monitoring stations. |
| Tetrachloroethylene | Achievement of the Environmental Quality Standards regarding tetrachloroethylene has been confirmed at all the monitoring stations. |
| Dichloromethane | Achievement of the Environmental Quality Standards regarding dichloromethane has been confirmed at all the monitoring stations. |
◆ Air Pollution Monitoring System - for Atmospheric Monitoring in Tokyo -
Overview of air pollutants
Tokyo Metropolitan Government set instruments for monitoring the conditions of air pollution at 82 sites in Tokyo so that 24-hour continuous measurements could be conducted. The data (measurements obtained every hour) are reported as fast estimations on the air pollution information map at the Web site of the Bureau of Environment, Tokyo Metropolitan Government.
[Monitoring Spots]
General air pollution monitoring stations (47 spots)
These are set to collect information about air pollution in
general areas, including residential zones.
Roadside air pollution monitoring stations (35 spots)
These are set to collect information about air pollution in
areas along the main roads and around intersections.
[Monitoring Items]
IItems defined by the Environmental Quality Standards
(5 substances):
Nitrogen dioxide, suspended particulate matter, photochemical
oxidants, sulfate dioxide, carbon monoxide.
Other items (7 items):
Nitrogen monoxide, methane, nonmethane hydrocarbons,
wind direction, wind speed, temperature, humidity.
in the text and access
