Japan Platform for Redesign: Sustainable Infrastructure (JPRSI)

Technology Information Related to the Transportation Sector

Air Pollution Improvement

Air Pollution Improvement

Air pollution is worsening in developing countries, especially in large cities. Vehicle emission is one of the main causes. For air pollution control, it is important to promote measures such as exhaust gas regulations, and the technologies to realize these measures in an integrated manner.

This page provides examples of measures, laws and regulations to improve air pollution related to the transportation sector, and technologies that contribute to air pollution improvement. (Last update 22 March 2023)

Policies, Measures and Technologies for Air Pollution Improvement

Policy Goals

Protection of health and environment is the goal of the air policies to prevent pollution and improve air quality in Japan. To this end, the air environment standards have been established and pollution control measures have been implemented.

  • Environmental Quality Standards are established as standards recommended to be kept up, so as to protect human health and conserve the living environment. Regarding the environmental conditions on the air pollution, the standards for air pollutants such as SO2, CO, SPM, NO2, Ox, PM2.5 and other hazardous air pollutants are established.
  • The following section provides the measures and technologies related to the transportation sector.

Measures

Measures against Emission Sources (regulatory approach)

Vehicle Regulation (New Vehicles)

Vehicle exhaust gas standards chevron_right

Vehicle Type Regulation (Vehicles in use)

Act on automobile NOx/PM chevron_right

Traffic vehicle noise regulation chevron_right

Fuel Regulation

Fuel content regulation chevron_right

Measures against Emission Sources (others)

Certifications

“e→AS” certifications for air quality-friendly fuel stations chevron_right

Assessment/Evaluation Tools

　

Air pollution monitoring chevron_right

PM2.5 emission Inventory chevron_right

Air pollution forecast models chevron_right

Technologies

“Avoid” Technologies

Transit-oriented development (TOD) chevron_right

“Shift” Technologies

Light Rail Transit (LRT), Bus Rapid Transit (BRT), new urban rail transit systems chevron_right

“Improve” Technologies

Exhaust gas aftertreatment devices

Diesel exhaust gas aftertreatment devices（DPF, catalysts） chevron_right

Next Generation Vehicles

Alternative fuel vehicles (CNG) chevron_right

Fuel substitutes (hybrid vehicles) chevron_right

Monitoring Technologies

Emission monitoring systems and sound level meters chevron_right

Real time online portal for air pollution monitoring data, online portal for traffic vehicle noise annual data chevron_right

Air pollution forecast models chevron_right

Measures to Improve Air Pollution

Measures against emission sources (regulatory approach) : Vehicle Regulation (New vehicles)

Vehicle emission regulations
  • In Japan, the vehicle emission regulations are applied for CO, NMHC, NOx, PM , etc. , which vary with vehicle categories, gross weight and model years.
  • Since the regulations were introduced in 1966, they have been tightened over the years. About diesel heavy duty vehicles, emission levels for NOx and PM today are 7% and 1% compared to those in 1994. And about gasoline/LPG passenger vehicles, the levels for NOx and HC today are 2% and 3% to those in 1973.

Measures against emission sources (regulatory approach)：Vehicle Type Regulation (Vehicles in use)

Act on automobile NOx/PM
  • The NOx/PM act regulates the NOx and PM standards for the vehicles in use particularly in the urban areas with severe air pollution due to heavy traffic.
  • Also, the Act requires the companies owing 30 or more designated vehicles in the concerned areas to develop and report the vehicle use plans.​
Traffic vehicle noise regulation
  • For traffic noise, limits are introduced to request the invocation of measures such as road traffic restrictions.
  • For noise emission from motor vehicles, the permissible limit has been set in consideration of the impact on vehicle traffic noise, domestic driving conditions, and harmonization with international standards, while take into account the progress of vehicle noise reduction technology.

Measures against emission sources (regulatory approach)： Fuel Regulation

Fuel content regulation
  • The limit of components in Gasoline and Diesel fuel is regulated , in order to prevent the deterioration of exhaust gas emissions.
  • For example in gasoline fuel, the component ratio shall be equal or less than 10ppm for sulfur, and 1% in volume for benzene. In diesel fuel, the component ratio shall be equal or less than 10ppm for sulfur.

Measures against Emission Sources (others)：Certifications

Air Environment-Friendly SS(“e→AS”)Certification System
  • Aiming to reduce the emission of the fuel evaporative gas, MOE and the Agency for Natural Resources and Energy (ANRE) will certify gas stations (or service stations: SS) equipped with petroleum-fueling facilities with devices that collect fuel evaporative gas generated in fueling automobiles as an Air Environment-Friendly SS. Through this effort, MOE and ANRE aim to promote popularization of this system. MOE and ANRE certificate SS according to the collection ratio of fuel evaporation gas.
e→AS certifications
e→AS certifications (Japanese Only)

Assessment/Evaluation Tools

Air pollution monitoring
  • Air pollution is constantly monitored by the local governments at the monitoring stations (continuous monitoring). The objectives of monitoring include to trigger the measures in emergencies with photochemical oxidant or PM2.5 high concentration events.
  • Air pollution monitoring also helps identifying the high concentration areas and their measures, and performance of these measures.
PM2.5 emission inventory
  • Ministry of the Environment, Japan (MOEJ) compiles and updates the PM2.5 emission inventory on a regular basis.
  • PM2.5 emission inventory provides the basis to find the yearly trends of the emissions from the Source sectors, and to evaluate the progress of the emission control measures in the concerned sectors.
  • PM2.5 emission inventory data set is also used in the atmospheric numerical models, which contribute to PM2.5 and other air pollution forecasts. Such models serve as the tools to identify potential measures against the emission sources as well as to evaluate the effectiveness of such measures.
Air pollution forecast models
  • A numerical simulation model is an important tool for estimating the distribution and trends of air pollutants such as PM2.5 and photochemical oxidants.
大気汚染濃度数値モデル
Source: https://www.nies.go.jp/kanko/kankyogi/64/column4.html(Japanese Only)
  • Current status are analyzed in detail based on the Ox monitoring data, the latest findings on the Ox formation mechanisms are collected, and the precursors’ emission inventories and simulation models are updated with better accuracy, for an enhanced understanding of contributions to the Ox formation.
  • Also, the simulation models are used to verify how much contribution the emission controls and voluntary measures on the Ox precursors have made on the concentrations.
  • The future forecast on the air quality, necessary Ox measures and reduction scenarios are examined by using the simulation models.

Technologies to Mitigate Air Pollution

“Avoid” Technologies

Transit oriented development (TOD)
  • TOD builds the cities based on the public transportation with less dependence on private vehicles. Japan has placed the priority on trains, metros, buses, etc. in its urban development, and hence it has been viewed as one of the TOD developed countries in the world.
  • Kashiwanoha Campus Station aims to building the transportation systems based on the TOD concept as an advanced EST model city. The station also aims to strengthen the urban functions by closely connecting with Kashiwa Station, which is further connected to the Tokyo areas by JR East and Tobu lines.

“Shift” Technologies

Light rail transit (LRT), bus rapid transit (BRT), new urban rail transit systems
  • Technologies to improve the public transport services include LRT and BRT. BRT is a bus system with higher-order functions that can ensure fast and on-time delivery and increase transportation capacity by combining articulated buses, bus-only roads, etc.
Light rail transit (LRT), bus rapid transit (BRT), new urban rail transit systems
Source: Toyama City(Japanese Only).
  • Toyama City launched the LRT Project in 2003, to build a “Compact City” centered with the public transportation such as rail and bus connected with the walking districts in the vicinity. The LRV nicknamed “Portram” started operating in April 2006. Its feature is low-step floor.
Light rail transit (LRT), bus rapid transit (BRT), new urban rail transit systems
Source: NIES “Tenbou”(Japanese Only).

“Improve” Technologies：Exhaust Treatment Technology

Diesel exhaust treatment devices（DPF, catalysts）
  • To reduce PM emitted particularly from diesel vehicles, there is a device as Diesel Particulate Filter(DPF), which can reduce PM significantly. The DPF captures PM with its porous filter by passing exhaust gas. When PM accumulates much enough, the DPF raises its temperature to oxidize the PM accumulated.
  • Oxidation catalysts also remove PM from diesel exhaust gas by catalyst functions of platinum etc.
  • Recently, exhaust gas is treated entirely by the combined system of the DPF and the catalyst, and consecutive PM oxidation DPF is now being developed.

“Improve” technologies：Next Generation Vehicles

Alternative fuel vehicles (CNG)
  • CNG vehicles run with CNG stored in the high-pressure gas container. It is necessary to build the CNG fueling stations at the same time.
  • City of Toyama concluded an MOU with Semarang City, Indonesia, to assist to retrofit the diesel buses owned by the Semarang city transport company with the engines which can use CNG.
Alternative fuel vehicles (CNG)
Source: http://gec.jp/jcm/projects/18pro_ina_03/
Hybrid vehicles
  • Hybrid vehicles are powered by one or more electric motors using energy stored in batteries and an internal combustion engine which is driven only when driving efficiently. Also, the battery is charged through regenerative braking and by the internal combustion engine.

Monitoring Technologies

Emission　monitoring systems and sound level meters
  • Reliable monitoring devices are developed and sold, in compliance with the “manual for the constant air quality monitoring manual” of Ministry of the Environment, Japan.
  • Various types of sound level meters are also available. These devices are compatible with the guidelines and manuals of Ministry of the Environment.
Emission　monitoring systems and sound level meters
Source: https://www.horiba.com/int/process-and-environmental/
Emission　monitoring systems and sound level meters
Source: https://rion-sv.com/
Real time online portal for air pollution monitoring data
  • The provisional hourly results of air pollution monitoring stations are published online on a real-time basis in the website of Ministry of the Environment, Japan. The concentration distribution is displayed visually on the map. The website is known as “Soramame-kun.”(Atmospheric Environmental Regional Observation System : AEROS)
  • Some private companies provide their own modelled PM2.5 concentration forecasts etc. for their own business activities.
AEROS
Source: AEROS(Japanese Only)
Japan Weather Association
Source: Japan Weather Association(Japanese Only)
Air pollution forecast models
  • National Institute for Environmental Studies (NIES) has developed an atmospheric model “VENUS” (Visual atmospheric ENvironment Utility System) with support from Ministry of the Environment.
  • VENUS estimates more than ten kinds of air pollutants, and the VENUS website provides the PM2.5 and Ozone estimates, the most concerned of all the air pollutants.
VENUS
Source: https://venus.nies.go.jp/ (Japanese Only)