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A Partnership for Sustainable Air Quality Improvement in Bangkok
Current Status of Air Quality in Bangkok
Program Summary
Program Activities
Activity Updates
Contact Us

A Partnership for Sustainable Air Quality Improvement in Bangkok

In Thailand and throughout Asia, diesel vehicles – such as pick-up trucks, buses, and delivery trucks - are the backbone of transport systems. Unfortunately, diesel vehicles are responsible for exhaust emissions that have considerable environmental and health impacts. The scale of these emissions increases with poor vehicle maintenance, improper vehicle repair, use of older vehicle technology, low fuel quality, fuel adulteration, lack of monitoring and enforcement of standards, and poor institutional capacity.
There are over 10,000 diesel-powered buses in Bangkok. Buses account for more than 50% of all passenger trips.

Several technical and policy options exist to address these problems, ranging from improved transport management and driver behavior to new technologies based on cleaner diesel or alternative fuels. However, there is very limited real-world information and data on the possible emissions reductions of a combination of policies and technologies in the context of developing countries, and this lack of information hampers the selection and implementation of effective measures and programs. Partly as a result, few cities in developing countries have taken a comprehensive approach to control diesel emissions.

The “Developing Integrated Emission Strategies for Existing Land Transport” (DIESEL) Program aims at developing a comprehensive understanding of in-use diesel vehicles, testing various emission control options, and improving decision-making for better urban air quality in Asian cities. Bangkok, Thailand, has been chosen the pilot city for implementing the DIESEL Program. In Thailand, the DIESEL Program is implemented by the Pollution Control Department and the Department of Land Transport, with assistance from the World Bank and the U.S.-Asia Environmental Partnership, a regional program of the United States Agency for International Development. Public-private partnerships with strategic industries and research institutions provide additional support.

Current Status of Air Quality in Bangkok

Thai Air Quality Monitoring Network

The Pollution Control Department (PCD) began monitoring air quality in Thailand in 1983. PCD’s 71-site monitoring network collects information on a variety of pollutants, such as CO, NO2, SO2, and ground-level ozone.

The Pollution Control Department has 71 air quality monitoring sites across Thailand.

Click here for more information on Thailand’s air quality monitoring network. PDF (0.21MB)

Institutional Arrangements for Air Quality Management

Several agencies share the responsibility for air quality management in Thailand.

Click here for a summary of the responsibilities of the agencies involved. PDF (0.16 MB)

Vehicle Emission Regulations and Data

Emission regulations for diesel vehicles are divided into emission standards for Light Duty Diesel Vehicles and standards for Heavy Duty Diesel Vehicles. New diesel vehicle regulations are in line with European standards and emissions test procedures.

Light and Heavy Duty Diesel Vehicle Emission Standards
Type LevelReference Standards Standard No.Enforced
Light Duty Diesel Engine 494/12/EC
- for Direct Injection
TIS1435-1997Jan1, 1999
- Ref. Weight not more than 1,250 kg.
- Ref. Weight more than 1,250 kg.
- Direct injection Engine
TIS1875-1999 Oct 1, 1999
Oct 1, 2000
Sep 30, 2001
Heavy Duty Diesel Engine2995/542(A)EEC (EURO 1) TIS1290-1995May 12, 1998
395/542(A)EEC(EURO 2)TIS1295-1998May 23, 2003

New diesel vehicle regulations are based on European standards and emission test procedures.

Click here for more information on vehicle emissions regulations and data. PDF (90 KB)

PM Concentration and Health Impacts

Particulate matter (PM) emissions from diesel vehicles pose a major health threat in Bangkok and other Asian cities. Fine particulates categorized as PM10 (less than 10 microns) and PM2.5 (less than 2.5 microns) penetrate deep into the lungs and cause respiratory illness. The health costs of PM emissions are forecast to be around 20 billion Baht in 2004. Since the late Nineties, PM emissions have declined in Bangkok through improved mobile and other source control measures.

Click here for more information on PM concentration and health impacts. PDF (0.23 MB)

Program Summary

The DIESEL Program aims to facilitate a better understanding of factors affecting vehicular emissions, to develop knowledge-based reference tools, and to propose cost-effective control and strategic policy options in order to help policymakers implement effective measures for in-use diesel vehicle pollution reduction (click on link for an explanation of why DIESEL is focusing on in-use vehicles). The Program places emphasis on applying the findings to actual attempts to promote sustainable development instead of leaving them simply as a database or policy recommendations. Thus, providing policymakers with capacity building opportunities is an important aspect of DIESEL activities.


The Program was formulated according to five principal objectives:

  1. Enhance the capacity of local stakeholders in Bangkok and other cities to understand the factors affecting local and global emissions of their in-use diesel vehicle fleet.
  2. Analyze the potential to reduce local emissions, focusing on Particulate Matter (PM), and improve fuel or energy efficiency of selected technical alternatives of interest to major cities.
  3. Assess the effectiveness of a select number of viable and affordable policies and technical measures to reduce diesel vehicle emissions that maintain or improve overall accessibility of the poor to the transport system.
  4. Prepare tools to assist decision makers in developing urban diesel emission action plans that reflect the political, social, and economic implementation realities of developing countries.
  5. Disseminate research findings through the Clean Air Initiative networks in Africa, Asia and Latin America.


There are three components of the DIESEL Program in Bangkok, as shown in the figure below. Components 1, 2 and 3 are part of the DIESEL Pilot in Bangkok, while dissemination activities will be part of the overall DIESEL Program, directly coordinated by the Clean Air Initiative for Asian Cities (CAI-Asia) and its partners. Click on link to see the specific program activities under each of these components.

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DIESEL is jointly implemented by the Pollution Control Department and the Department of Land Transport with support from a wide-range of stakeholders. The Clean Air Initiative for Asian Cities coordinates the inputs of international partners, which include the World Bank, the United States-Asia Environmental Partnership, the United States Environmental Protection Agency, and the Clean Air Task Force. Alliances with multinationals such as Volvo and Lubrizol and Thai private sector companies are also an important part of DIESEL’s implementation strategy.

Pollution Control Department

The Pollution Control Department (PCD) coordinates the City Program Management Team (CPMT), which is responsible for the implementation of the pilot program in Bangkok. The Automotive Emissions Laboratory of the PCD is also involved in implementing the DIESEL Program. Thai language presentationPDF (0.16 MB) on the Automotive Emissions Laboratory is available here. PCD has a successful record of accomplishment implementing programs that have improved air quality throughout Thailand. For information on the success of other PCD air quality initiatives,

Department of Land Transport

The Department of Land Transport (DLT) exercises responsibility for on-road enforcement of vehicle safety and emissions standards. In association with the DIESEL Program, DLT will manage the collection of computerized vehicle registration records of existing in-use diesel vehicles in Bangkok.

Clean Air Initiative for Asian Cities

The Clean Air Initiative for Asian Cities (CAI-Asia) promotes and demonstrates innovative ways to improve the air quality of Asian cities through partnerships and sharing experiences. The Secretariat of CAI-Asia is jointly shared by the World Bank and Asian Development Bank, and its members come from national government agencies, Asian cities, NGOs and academia, private sector companies, and international development agencies and foundations.

United States - Asia Environmental Partnership

The United States - Asia Environmental Partnership (US-AEP) is an initiative of the U.S. Agency for International Development that promotes environmentally sustainable growth and improved quality of life in six Asian countries - India, Indonesia, the Philippines, Sri Lanka, Thailand, and Vietnam. US-AEP is playing a key role in conducting the DIESEL Stratified Survey to quantify factors that affect emissions from diesel vehicles.

Program Activities

This section describes each of the components, provides updates about each project activity, and presents key information and data that has been collected in each component thus far. To see a more detailed timeline of the project, please click on the following link.

Component1: Gathering City-Specific Data

The first component of the DIESEL Program focuses on gathering existing information and relevant data for the eventual assessment of policies and measures to reduce diesel emissions in Bangkok. The Program has undertaken, or is in the process of undertaking, a number different actions, including:

1. Researched a number of topics related to diesel vehicle emissions in Bangkok, including:

OR Click here for the complete report. PDF (1.32 MB)

2. Collected information on the current status of air quality in Bangkok:

3. To supplement the existing data, completed a stratified survey PDF (1.46 MB) of the owners of diesel-engine vehicles targeted at select characteristics, i.e. type, age, mileage, maintenance practice, and use (click on the link for the final report).

4. Estimate particular matter (PM) emission factors for different diesel vehicle types under conditions more representative of “real-world” conditions with the objective of estimating overall emissions. To this end, the following tasks will be performed:

  • Collect and evaluate existing data on the modal share of different vehicle types, age and mode of operation.
  • Through baseline emission testing, establish a limited number of diesel vehicle emission factors for use in an emissions inventory (click on link to view the testing protocol PDF(16 KB), including driving cycles, that has been established).
  • Develop an emissions inventory for diesel vehicles and feed the results back to a larger program building a city-wide emissions inventory working in partnership with the environment agency.

Component2 : Analysis of Policy and Technical Options

The second component of the program will study the emission reduction potential of a number of policy and technical options. A few policy and technical options will be analyzed in detail for their emission reduction potential and cost-effectiveness. The tests will quantify the costs and scope for emission reduction, and assess the operational challenges under real-world conditions. A number of activities will be implemented under this component, including:

Component3 : Develop Action Plans and Stakeholder Consultation

The pollution reduction options identified under Component 2 can achieve their intended results only if they are accepted and implemented by stakeholders. The selected options will be analyzed and discussed from economic, environmental, technical, stakeholder, social, and sustainability perspectives. Only those options that are widely accepted have a real chance to succeed and an action plan around those options will be implemented. To accomplish this, the following tasks will be undertaken:

  • Engage in policy dialogues among stakeholders to discuss selected options using the analytical and informational tools developed
  • Discuss social, economic, and political difficulties vs. environmental benefits of different options and decide on options to be implemented
  • Develop action plans for options to be implemented

Regional Disseminator

The outcomes of the study, including the knowledge base and analytical tools, will be discussed in expert panels and disseminated through the Clean Air Initiative for Asian Cities (CAI-Asia) to a number of partner cities in developing countries. At the end of the project, an event will be organized to bring together leading experts, key companies, and decision makers to communicate the outcomes of the project. Furthermore, a section of the Clean Air Initiative’s web site will be dedicated to the program, and the Clean Air Initiative’s distance learning courses will be used to disseminate the information worldwide.

Activity Updates

Emission Testing for Developing Bangkok Emission Factors are now performing at PCD automotive emission laboratory (from Oct 18, 2004 until August 2005)

DIESEL’s second planning meeting was held with partners, collaborators, and local agencies in February. The objective of the meeting was to provide an overview of current progress and future activities, to invite comments and suggestions, and to discuss the needs and specific opportunities for current and potential partners.

Summary of Second Planning Meeting (February 17, 2004)

The second planning meeting was held with the partners, collaborators and local agencies in Thailand on February 17, 2004 in Bangkok at PCD. The objective of the meeting was to provide an overview of current progress and future activities, to invite comments and suggestions, and to discuss the needs and specific opportunities for current and potential partners.

The meeting was attended by 84 stakeholders represented a wide range of stakeholders, including private bus companies, bus operator associations, traffic police, vehicle manufacturers and fuel oil companies, local and foreign emissions control technology providers, international agencies, and a large number of government agencies from the steering committee. While there were formal presentations, a lot of the time was devoted to discuss technical issues and provide a neutral perspective on various topics.

The major observations for the meeting and follow up discussions can be summarized as follows:

1. Emissions from diesel in-use vehicles are a major issue and can be controlled by policy and technology options. Implementation of identified options is not easy. The DIESEL program and specifically the Bangkok Pilot represents a unique opportunity for the stakeholders to collaborate and agree on a unified protocols for various tasks to facilitate replication of such programs and use of data for other cities.

2. The DLT database is being revised and the stratified survey being conducted will provide us with the information needed to design the test matrix for this project. The stratified survey will have to be modified and information on vehicle categories 5-9 (Bus and Truck) will be collected separately.

3. The most effective way to reduce the number of gross polluters (buses and trucks with excessive visible smoke and high PM emissions) is by encouraging or mandating good maintenance practices. Experience in Hong Kong and elsewhere is that a loaded test in I & M process is more effective than the free acceleration test currently used in Thailand, based on international experience. For broad based support and acceptability of the program, visible gross polluters needs to be dealt with and police can play an important role their identification. PCD and DLT will need to explore feasibility and modality of introducing loaded emissions test as a part of their I & M system in Bangkok for the diesel commercial vehicles.

4. PCD has a good laboratory and staff for emissions factor measurements (one of five or six around the world for heavy duty dynamometer). The current heavy duty vehicles test dynamometer has not been calibrated for actual road load for local condition. This can be obtained by a coast-down test (EPA provided software for this test). PCD may be able to get this from the manufacturers too.

5. A good base line of emissions from a wide variety of vehicle categories but relatively wide confidence level may be acceptable. In particular, the number of tests and the associated confidence level, depends on the magnitude of emissions reduction desired to be delivered by the adoption of particular improvement strategies. Where technologies can only deliver small reductions more tests and more stringent procedures are needed. Given the limited resources for testing, it is important to test technologies and strategies which are likely to be effective or viable in Asia.

6. Length of the driving cycle. The proposed driving cycle for Bangkok is good and representative of actual conditions but is too long. It is desirable to shorten this driving cycle and still be representative of the local conditions. This will reduce lab time per vehicle, reduce risks of tire failures and increase the number of tests.

7. Continuous PM monitoring systems have been demonstrated to generate reliable and comprehensive data for emissions factor measurements, particularly if the cumulative emissions measured by these systems can be calibrated against a traditional filter measurement, taken in parallel over the whole cycle. PM measurements during different phases of the driving cycle have potential to increase the value of gravimetric (filter) PM measurements, but only over fairly extended drive cycle segments.

8. Participants showed interest in having an analytical tool like the IDEAS model. Participants were willing to work with us on developing the framework to analyze the technical and institutional options and scenarios for controlling diesel emissions.

9. We should explore possibility of establishing relationship with universities so that their students can assist with data gathering and modifications of the excel based program for Thailand.

10. The topic of private sector contribution was discussed at length and while many in the audience showed interest and filled out a short survey. In order to secure core project funding from U. S. Agency for International Development (USAID) to match World Bank and other contributions, project would need to provide letters of intent to USAID demonstrating actual contributions from private sector and other partners.

11. Project would send the sample letter of intent that will send to USAID along with the project proposal to each organization by March 1, 2004. Each organization would change the content and add their contribution in the letter and send back to the project.

12. Need to improve our outreach and information dissemination locally and internationally were mentioned by some of the participants.

13. During the meeting, alternative fuel is one of the issues had been discussed. PTT representative addressed that in many major cities such as Mexico, LA, Mumbai, Sydney etc. are promoting using natural gas for mass transportation since it produces much better emission than diesel, particularly PM. For Thailand, which there is indigenous natural gas reserves, therefore natural gas could be the most reasonable potential fuel option because it does not only provide better emission but it also help the country reduce imported fuel reliance. The proper vehicle selection together with the study of NGV emission and utilization may be considered as one option in DIESEL project.

Contact Us

To explore how your organization can partner with DIESEL contact

Project Management Group Coordinating Group

Supat Wangwongwatana
(Steering Committee Chair Person)
Deputy Director General, PCD

Mingquan Wichayarungsaridh
(Project Manager)
Director of Air Quality and Noise Management Bureau, PCD

Jitendra (Jitu) Shah
(World Bank Project Manager)
Senior Environmental Engineer, The World Bank

Manida Unkulvasapaul
(World Bank Project Coordinator)
Senior Environmental Specialist, The World Bank

Siwaporn Rungsiyanon
(PCD Project Coordinator)
Environmental Officer, PCD

Ekbordin Winijkul
(Project Coordinator)

World Bank Advisory Group PCD Advisory Group

Masami Kojima
(Technical Advisor)
Senior Energy and Environment Specialist, The World Bank

Paul Procee
(Technical Advisor)
Urban Environmental Specialist, The World Bank

Sarath K. Guttikunda
(IDEAS Coordinator)
Environmental Specialist, The World Bank

Panya Warapetcharayut
(Advisor) Director of Automotive Air Pollution Division, PCD

Ittipol Paw-armart
(PCD Laboratory Manager)
Environmental Officer, PCD

Vanisa Surapipith
(PCD Modeler)
Environmental Officer, PCD

โทร 0 2298 2349-50 โทรสาร 0 2298 2357
E-mail : diesel _reduction(at)pcd(dot)go(dot)th