Introduction Health impact assessment is increasingly recognized as a critical tool for assessing and managing how development activities, plans, and policies may affect public health, including in the context of climate change. It provides a structured approach for decision-makers to understand both the positive and negative impacts on health. The tool has a long history of successful implementation by countries and international agencies, including the World Health Organization (WHO), which defines it as “a combination of procedures, methods, and tools that systematically judges the potential effects of a policy, plan, program, or project on the health of a population and the distribution of those effects within the population” in the Gothenburg consensus paper. Health impact assessments are flexible and can be applied at different scales—local or national—and across a wide range of contexts. They promote cross-sectoral collaboration, bringing in sectors beyond health to help ensure that decisions do not inadvertently worsen health or inequality, and to help identify opportunities to enhance health co-benefits. In Asia and the Pacific, organizations such as the Asian Development Bank (ADB) are strengthening the use of health impact assessment to better integrate health considerations into climate and environmental planning. This approach is guided by ADB’s Environmental and Social Framework, which integrates health impact assessment as part of the standard process to safeguard communities and the environment. The framework underscores how climate change affects health conditions and quality of life—highlighting the importance of considering these factors in project design and implementation. The role of health impact assessment in addressing climate and health challenges was also highlighted at the Inaugural Western Pacific Action Forum on Climate-Resilient and Sustainable Health Systems, where regional partners shared experiences in applying health impact assessment to strengthen health systems and community resilience. What Tools are Available to Assess Health Risks Linked to Climate Change? Several complementary tools can help governments assess and manage the links between health and climate risks. Health risk assessment is a classic environmental health approach used to define the magnitude of risk by considering the likelihood of an event, the resulting exposures, and the severity of potential outcomes. It evaluates hazards associated with extreme weather events such as heat waves, floods, or storms by examining exposure and vulnerability. Vulnerability and adaptation assessment offers a framework to identify climate-related health risks, assess vulnerabilities in communities, and recommend policies to strengthen health systems. It helps national and local governments and public health officials understand risks, prioritize adaptation actions, build workforce and infrastructure resilience, develop surveillance systems, and collaborate with other sectors. It also provides critical inputs into the development of Health National Adaptation Plans that serve as a foundation for long-term climate–health planning and capacity building. WHO has also developed guidance specific for health vulnerabilities stemming from the impacts of climate change. It provides advice on developing climate-resilient and environmentally sustainable healthcare facilities. This tool focuses on strengthening workforce preparedness, sustainable use of energy and water, safe waste management, and robust infrastructure. It is complemented by a checklist to assess health facilities vulnerabilities that can be repeated to monitor vulnerabilities and resilience over time. Other examples include guidance on specific climate-related hazards and contexts such as workplace heat stress and climate-resilient water safety plans. What Role Does Health Impact Assessment Play Among these Tools? Health impact assessment provides a comprehensive way to evaluate both the potential harms and benefits of projects, policies, or plans, including those influenced by climate change. ADB’s Environmental and Social Framework brings health impact assessment–either as a standalone or integrated assessment process—into the mix of standard considerations for safeguarding people and their places. This allows for an assessment of the overall health burden attributable to a project such as emergency health support, labor influx, and the spread of communicable diseases. It emphasizes the importance of stakeholder engagement with communities and public health authorities to inform any health impact assessment. How Do these Different Assessment Tools Complement One Another? All these tools share fundamental characteristics: they assess potential health impacts, recognize unequal distribution of impacts (vulnerability and equity), and provide evidence for climate adaptation, particularly for vulnerable populations. They operate at multiple levels—policy and system scale, facility operations, and community implementation—and serve as practical instruments to turn high-level assessments into measurable action. Combining different tools helps capture a fuller picture of climate–health interactions because health is shaped by environmental, economic, and social factors. These tools rely on interdisciplinary collaboration and cross-sectoral coordination, drawing on climate science, environmental health, epidemiology, socio-economic data, and community perspectives. How Do Countries Decide Which Tool to Use? Each tool has a specific purpose, depending on what decision-makers (e.g., health managers, donors) need to understand or achieve. The table below provides examples of when each tool is relevant. Tool When to Use Focus Results Health impact assessment Assess the potential health effects (positive and negative) of a project, policy, plan, or program Policy or project specific Recommendations to improve design, mitigate harm, and enhance health benefits Vulnerability and adaptation assessment Understand who is vulnerable to climate-related health risks, and what adaptation options exist Health system and health facilities Baseline vulnerability profile; prioritized adaptation options; basis for Health National Adaptation Plans Health risk assessment Assess hazards, exposures, and vulnerabilities, and quantify the likelihood and severity of specific health risks Hazard specific Quantified risk levels; thresholds for action; prioritization of risks needing management Can these Tools be Combined for Greater Impact? Countries can often use several tools together to get a more complete picture of climate–health interactions. For example, Lao PDR’s Health National Adaptation Plan integrated findings from both vulnerability and adaptation assessments and health risk assessments. These showed that health impacts were excluded from the mitigation plans of other sectors (e.g., energy, waste management, and transport) and recommended an assessment of co-benefits. A subsequent health impact assessment of solid-waste management mitigation policies identified significant health benefits and recommended ways to maximize health outcomes while reducing greenhouse gas emissions. By linking findings across tools, countries can better align health outcomes with climate mitigation and adaptation strategies and integrate health into economic planning and costing. What is Next for Health Impact Assessment in the Region? As climate-related health impacts expand, the next steps for health impact assessment in the region involve strengthening the evidence base, developing additional guidance, and building further technical capacity to support resilient health systems. Health impact assessment is expected to continue as part of the mix of tools routinely applied to assess the health impacts of climate change. While the selection of tools may differ depending on context, skills and preferences of the assessment team, the integration of fundamental principles such as risk, vulnerability, and equity will guide their use. Together, these principles can help ensure that different tools continue working toward the shared objective of creating more climate-resilient systems and communities. Andrew Bucu, Brian Riley, Emma Marsden, and Eduardo Banzon contributed to this article. Resources Asian Development Bank. 2024. Environmental and Social Framework. ADB. 2018. Health Impact Assessment: A Good Practice Sourcebook. Lao Ministry of Health, GEF, UNDP, WHO. Health National Adaptation Plan for Building Climate Resilient Health Systems in Lao People’s Democratic Republic 2025–2030. World Health Organization. 2021. Climate Change and Health Vulnerability and Adaptation Assessment. WHO. 2021. Strategic Toolkit for Assessing Risks: A Comprehensive Toolkit for All-Hazards Health Emergency Risk Assessment. WHO. 2020. WHO Guidance for Climate-Resilient and Environmentally Sustainable Health Care Facilities. WHO Regional Office for Europe and the European Centre for Health Policy. 1999. Health Impact Assessment: Main Concepts and Suggested Approach. Gothenburg Consensus Paper. Ask the Experts Carlos Corvalan Health Expert Carlos Corvalan joined the World Health Organization (WHO) in 1993 as coordinator for environmental and occupational health. From 2008 to 2015, he served as senior advisor on risk assessment and global environmental change at the Pan American Health Organization/ WHO. He later became an adjunct professor at the Faculty of Health, University of Canberra, and deputy director for environmental health at the New South Wales Ministry of Health. Ben Coghlan Consultant, Asian Development Bank Dr. Ben Coghlan is a health security expert. He is a public health physician and medical epidemiologist focused on strengthening health systems to address major public health challenges in Asia and the Pacific. His work has covered COVID-19, climate and environmental change, aging and non-communicable diseases, digital transformation of healthcare, and universal health coverage. He is formerly a senior health specialist with ADB’s Health Team. Helen Brown Health Impact Assessment Expert Helen Brown served as director of the WHO Collaborating Centre for Health Impact Assessment from 2014 to 2021. Her research focuses on the complex interactions between health and climate change, with particular focus on adaptation and vulnerable groups. She has worked closely with the WHO to strengthen capacity in health impact assessment and has developed and delivered training on health impact assessment, climate change, and public health across Asia and the Pacific. Leave your question or comment in the section below: View the discussion thread.