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Retrofit Programs


In December 2000, the Tokyo Metropolitan Government (TMG) adopted a new “Ordinance on Environmental Preservation”, which includes an array of regulatory measures to control air, water, soil, as well as noise pollution. An important part of the Ordinance is the “Countermeasure Against Vehicle Pollution” program, which includes the following components:

  • Diesel emission control regulation (retrofit program)

    Certain categories of in-use diesel vehicles have to be retrofitted with emission control systems to reduce PM emissions. Vehicles failing this requirement are to be banned from travel in the TMG area.

  • Vehicle environmental management plan

    Businesses which own over 30 vehicles must produce an environmental management plan, outlining the steps to reduce pollution, and report on the implementation progress.

  • Use of low emission vehicles

    In businesses that use over 200 vehicles, a certain percentage of the fleet must be “low emission vehicles”. The “low emission vehicle” designations are issued by the Ministry of Land, Infrastructure and Transport (MLIT) and also by the TMG based on the vehicle’s emission level. Low emission vehicle designations are issued in several categories, such as fairly low emission vehicle (25% emission reduction below national standards), highly low emission vehicle (50%), and ultra low emission vehicle (75%).

  • “Idling stop” practice

    Engines must be stopped while parking, unloading cargo, etc.

  • Prohibition of heavy-oil fuels

    Diesel fuels mixed with heavy oil must not be used for vehicles or construction machinery.

  • Vehicle pollution inspectors (G-men)

    Inspectors are assigned to promote the introduction and to enforce the above regulatory programs.

The new Ordinance took effect on April 1, 2001, with several provisions related to vehicle emissions (including the diesel retrofit program) effective October 1, 2003. Vehicle pollution measures similar or identical to those adopted by the TMG have also been implemented by a number of neighboring prefectures (Kanagawa, Saitama, Chiba,...).

Diesel Emission Regulations

Particulate matter emissions from in-use diesel vehicles must be reduced by retrofitting with emission control devices. The retrofit requirements apply to buses, trucks, and special category vehicles based on buses and trucks, such as campers, garbage collection trucks, and refrigerator/freezer vehicles. Passenger cars are not subject to retrofit requirements.

The PM emission reduction requirements depend on the vehicle emission level at the time of its manufacture (i.e., emission certification level). Older vehicles have higher PM reduction requirements. Newer vehicles, which meet more stringent new engine emission standards, have more relaxed PM emission reduction requirements. The retrofit program has a two-tier structure: the Tier 1 requirements become effective in October 2003. Somewhat more stringent Tier 2 PM emission reduction requirements come to power in 2005. These emission reduction requirements—along with their “Category” designations—are listed in the following table.

Table 1
Diesel PM Reduction Requirements and Categories
Vehicle Description Tier 1 (2003.10) Tier 2 (2005)
PM Reduction Category PM Reduction Category
Meets 1989/1990 standards, or
Fails to meet 1989/1990 standards
> 60%1 > 70%3
Meets 1993/1994 standards > 30%2 > 40%4
Meets 1997/1998/1999 standards N/A > 30%5
OEM-fitted with PM aftertreatment Meet PM standards Meet PM standards

All vehicles receive 7 years of grace period counting from the date of their first registration. In effect, vehicles must be retrofitted with PM controls either on the Tier 1/2 dates shown in Table 1, or in 7 years after first registration, whichever occurs later. This is illustrated by the following examples.

Example 1: A vehicle originally certified to the 1989 emission standards and first registered in 1993 will be prohibited from use in Tokyo starting in October 2003. The vehicle can be used beyond October 2003 if retrofitted with approved Category 1 PM control device.

Example 2: A vehicle certified to 1998 standards and first registered in February 2001 will be prohibited from use starting February 2008. The vehicle can be operated beyond that date if retrofitted with Category 5 PM control device.

It must be remembered that vehicles also must comply with the national “Automotive NOx and PM Law”, which is independent from the TMG regulations. Under the NOx and PM Law, the use of old vehicles may be restricted with different enforcement dates, depending on the vehicle type and age (emission level).

The TMG regulation applies to all diesel vehicles registered in Tokyo—about 420,000 (FY2000)—and to vehicles registered elsewhere, which travel to Tokyo. The daily traffic flow into Tokyo was estimated at 180,000 diesel vehicles per day (1999 data).

PM Emission Reduction Systems

All PM control devices have to be approved by the “PM Reduction Device Designation Committee”, established by the TMG. Control device manufacturers have to produce data on PM emission reduction, which have to fulfill the requirements shown in Table 1 for applicable model year engines, as tested on applicable Japanese emission test cycles. Manufacturers are also required to submit data on (1) reliability and durability of the emission control systems, (2) their safety, and (3) NOx/HC/CO emission performance (no “considerable increase” allowed). If criteria are met, the manufacturer receives approval under a given retrofit category/categories, Table 1.

Emission testing should be performed using diesel fuel of 50 ppm sulfur content, the type of fuel which is expected to be available (ahead of national regulatory requirements) in the areas of the retrofit program.

At the beginning of the program in October 2003, all devices approved in categories 1 and 3 were diesel particulate filters (passive or active), while devices in categories 2, 4 and 5 were diesel oxidation catalysts.


Once retrofitted, vehicles are affixed with stickers bearing the approval number of a given PM control device. A sample sticker is shown below.

Figure 1. Tokyo Diesel Retrofit Vehicle Sticker
Sample—no approval number; original diameter 125 mm

Owners of non-complying vehicles may receive injunction on operating the vehicle until retrofitted. If the injunction is not obeyed, the vehicle owner’s name is made public, and a fine of up to 500,000 yen is imposed.

At this time it is not clear if compliance programs will be implemented, which would determine emission durability of the PM control devices by emission testing.