The case that the research team has studied operated is an area of high-risk community in Nan Province, Thailand, close to the coal-fired power plant in Hongsa, Xayaburi Province, Lao People’s Democratic Republic. Although the power plant is located in Laos, it mainly provides electrical power to Thailand about 1,500 megawatts or 78% of the total generation capacity. The term of the power purchase agreement is 25 years. The investment in the power plant is about 80% from Thai public companies and 20% from the Lao state enterprise, with financing from 9 banks in Thailand. The use of coal as a fuel for electricity generation causes many kinds of pollution, especially air pollution such as small particulate matter 2.5 (PM 2.5), nitrogen oxides, sulfur dioxide, heavy metals, mercury, etc., that can induce cross-border impacts. Even though the power plant has installed technologies to capture pollution, namely 1) Flue gas desulphurization (FGD), 2) Electrostatic Precipitator (EPS), 3) Selective Catalytic Reduction (SCR), and CEM which is a continuous emission monitoring system at the tip of the stack to measure NOx Sox TSP O2 temp. etc. Sadly, the mercury capture equipment is not installed while the lignite coal used by the power plant contains mercury. In addition, the preparation of an environmental impact assessment report does not cover risky areas in Thailand. As the power plant is located in The Lao People's Democratic Republic (Lao PDR or LPDR), there is no obligation to carry out continuous surveillance on the Thai side. Although pollution may cross borders naturally, there are no regulations or legal agreements that cross nation-state boundaries. This is the reason for the development of surveillance systems for risky areas in Nan Province. The system is set up by public participation, local initiative and co-ownership to achieve sustainability, and draws expertise from various sciences to reinforce the search for facts and reality. Community-led Health Impact Surveillance System Development Project, Nan Province, Thailand, Case of Transboundary Pollution from Hongsa Coal-fired Power Plant, Laos, is a cross-disciplinary research. Under the support of Health System Research Institute (HSRI), there are 5 research projects working together, consisting the team from the Faculty of Science, Chiang Mai University; the Faculty of Engineering, Naresuan University; the Faculty of Liberal Arts, King Mongkut’s University of Technology Thonburi; Thai Public Broadcasting Service (Thai PBS); and the Thai National Health Foundation (NHF). The basic principle of designing this surveillance system is based on participatory action research, the precaution principle, that is, considering the risk without having to wait for health problems or patients to emerge. The surveillance framework focuses on changes in determinants of health, especially social determinants of health. This framework includes changes in environmental quality affecting the agricultural sector, which will result in income, labor mobility and immigration, as well as contamination in ecosystems and food chains that are at risk of disease and illness, especially for children and women of reproductive age. This is different from disease-oriented surveillance. Concepts involved in the design of this system include risk society; co-production of knowledge; citizen scientist; and environmental justice.There are four objectives of this research: 1) Develop a system for community-led health impact surveillance from coal-fired power plants; 2) develop collaboration mechanism for various actors; 3) to develop a model and process for producing knowledge together between experts and communities on coal power plant pollution awareness; and 4) to be a case study of environmental impact assessment cross border health in the process of monitoring the impact. The results of operations can be summarized as follows: 1. The process of developing a community-led health impact surveillance system can be sequenced as follow: building trust between the research team and the community, creating a cross-disciplinary team of experts, creating citizen scientists, and creating a system for recording, processing and storing a digital data and creating a data exchange platform which brings cooperation between groups in surveillance and mobilize policy measures to solve the problem. 2. The community-led health impact surveillance system consists of: 1) Surveillance teams, divided into cross-disciplinary research teams and community teams trained to be citizen scientists. These two groups work together in a form known as Co-creation of knowledge. 2) Surveillance tools. There are tools that require advanced skills of experts in various fields, and tools for citizen scientists to measure the quality of both chemical and biological environments. including indicators to observe changes as well as a tool used to collect various evidence called MOJO. 3) Recording and storage system have cooperated with Thai Public Broadcasting Service (Thai PBS) To develop a C-site platform for storing surveillance data and continually accumulate data until it becomes a large database. When there is a certain amount of data, it can be processed, interpreted and reported in a dashboard style and will be open to various sectors to access information and use it for their own work, including developing an environmental pollution warning system and an emergency response system from environmental pollution threats. 4) Cooperation Platform, which is a digital platform, is under C-site platform and open discussion area between different groups to reduce bias and balance the power of using data to govern or make decisions about big technology risks. 3. The methods of surveillance can be divided into 9 steps, which can be applied to other areas with similar risks of environmental pollution, namely: 1) Source analysis and pollution determination. 2) Define surveillance dimensions and risk chains 3) Aerial modeling in order to see the risky areas from the accumulation of pollution. 4) Build a cross-disciplinary research team to understand the risk situation in the area and vulnerable groups. 5) Create appropriate tools for the community. 6) Build a team of citizen scientists to monitor. 7) Collect data by citizen scientists. 8) Record data on the C-site for both cross-disciplinary researchers and citizen scientists. 9) Open up surveillance cooperation areas. 4. From the air modeling, it was found that pollution accumulated in 8 villages of Huai Kon Subdistrict and Khun Nan Subdistrict, Chaloem Phra kiat District. The research team therefore sets this area as a target for building a community-led health impact surveillance system by installing sensors to measure air quality, collecting samples of soil, sediment and water in creek, rainwater, fish, and villagers’ hair for analysis in the laboratory. We also organize a learning process and practice skills as citizen scientist for villagers, including teachers and students in the targeted areas. 5. Analysis results of acid gas condition is related to agricultural crop damage such as withered rice grains, disease outbreaks in plants. Mercury contamination was found in sediments, fish, and in human hair, but not exceeding the standard. 6. Therefore, the recommendations are as follows: 1) the emission control at the source, by installing a mercury capture, improved dust collector technology efficiency, nitrogen oxides and sulfur oxides capture. This should be implemented through the National Human Rights Commission of Thailand, and the ASEAN Intergovernmental Commission on Human Rights (AICHR). 2) And in the long term, there should be a mechanism to regulate transboundary pollution in ASEAN, including the use of financial institutions’ mechanisms for auditing in accordance with business and human rights principles. 3) To have a process to prove if the impact is from Hongsa Power Plant pollution or not, and then to have fair compensation, including paying for operations to rehabilitate contaminated areas. 7. Amend the Environmental Act in the section that related to environmental surveillance and adding content on joint governance of transboundary pollution. This research was used as a case study. In short, the surveillance system in this project is a cross-disciplinary and cross-operation between experts and the public, which can adjust the balance of power in environmental justice. That is to say, traditionally there was a line between recognized experts in possession of tools and knowledge-generating production processes, and lay people who are subject to risks and consequences under unknown situation, as information and knowledge production are blocked. But the experimental initiative in this project is to create a new power from the ability to produce knowledge by themselves from the people who are at risk and affected, in collaboration with various experts. The result is, in addition to scientific knowledge, movements and social networks also emerged. And there is a set of facts that can be used as evidence in further claims. Therefore, the production process which creates shared knowledge platform is an important part in rebalance of power this case, and in other cases where there are further risks to the environment and health.