Air Quality Control

1970s
The Tokyo Metropolitan Government (TMG) regulated air pollutants such as soot and smoke from factories through ordinances and other regulations.

1990s
In parallel with an increase in traffic, air pollution escalated, which was attributable to black smoke (particulate matter) caused by automotive emissions. TMG regulated exhaust gas from diesel vehicles in 2003.　

Present
The air quality in Tokyo has improved significantly. However, the concentration of photochemical oxidants and PM2.5 exceeds the environmental standards at many monitoring stations.

Comparison of achievements made when the national environmental standards were established and those as present
*1 Number of ambient air monitoring stations meeting the standard / The number of ambient monitoring stations with effective results
*2 FY1974 data
*3 FY2011 data

Recent Efforts
As concentration of photochemical oxidants and PM2.5 has to be lowered, TMG is working on measures to reduce emissions of the causative agents, such as volatile organic compounds (VOCs) and nitrogen oxide (NOx). Studies on generation mechanism and reduction of PM2.5 allow us to analyze seasonal primary causes, identify the influence of large-scale transport, and examine effective reduction methods.

* Promoting EV, pHVs （PDF：121KB）
- Subsidies, Tax exemptions

* Photochemical Smog Information(in Japanese) （外部サイト）

* Criteria for issuing a Photochemical Smog Warning(how to read the information) （PDF：125KB）