Introduction Air quality is improving in many Asian cities over the past decade, but it remains a major health and development challenge across Asia and the Pacific. An analysis by Clean Air Asia found that, between 2014 and 2024, 47% of the 694 Asian cities with sufficient long-term data showed clear and consistent improvements in air quality, with falling levels of fine particulate matter (PM2.5). Despite the progress, urban air pollution across the region remains high, with pollution levels in many cities continuing to exceed the World Health Organization’s (WHO) health-based air quality guidelines. The experience of cities that are improving air quality provides useful insights into what is driving these gains and what other cities can learn from them. What is Driving Progress? Clean air is essential to human health, well-being, and economic development. Yet Asia and the Pacific is home to many of the world’s most polluted countries and cities. Around 4 billion people breathe unhealthy air. In 2023, air pollution contributed to more than 2 million deaths in both the People’s Republic of China and India. Experience across the region shows that effective measures can make a difference. Since the first regional Better Air Quality (BAQ) conference in Hong Kong, China in 2002, knowledge of air pollution and how to address it has advanced considerably. Better monitoringNational governments have taken important steps to improve air quality management. Of 48 countries assessed, 27 have dedicated air quality legislation and 15 address air pollution through broader environmental laws. National air pollutant standards exist in most countries, yet many require improvement to align with WHO guidelines. Enhanced air quality monitoring efforts now offer governments and the public a more accurate picture of pollution. Cities such as Beijing and Jakarta are strengthening their monitoring systems to identify pollution hotspots. Together with emissions inventories and information on key pollution sources, these data are helping cities decide where and how to act based on local conditions, allowing measures to be targeted at the sources that matter most. Targeted actionTransport is a major contributor to urban air pollution in the region. Cities are investing in mass transit, including metro and bus rapid transit systems, and increasingly electrifying public transport. Hangzhou and Chengdu are also promoting cleaner vehicles, walking, and cycling, while Bangkok is combining transport measures with regional cooperation. More than 70% of imported passenger vehicles in Kathmandu were electric in 2025 because of favorable tax policies targeted at reducing transport-related pollution. Work on low emission zones in Indonesia, the Philippines, Thailand, and Viet Nam is helping cities identify ways to reduce transport-related air pollution. These approaches show the importance of matching transport interventions to local pollution sources and conditions. Agricultural burning also plays a crucial role. Smoke from burning crop residue can travel considerable distances from its source. In Punjab, Pakistan, ADB and other development partners are supporting farmers to adopt agricultural technologies that reduce the need to burn crop residues. These examples show why solutions need to reflect the main sources of pollution in each location. Coordinating across sectorsActions taken within specific cities alone are not always enough. Air pollution transcends geographical boundaries, and pollution from nearby areas can weaken local initiatives to reduce emissions. Effective air quality management can therefore require action beyond individual city boundaries. The Greater Beijing–Tianjin–Hebei region shows how coordinated action can work at scale. Programs of government and international financial institutions, including ADB, combined actions in electric transportation, cleaner heating and cooling, better agricultural waste management, stronger air quality monitoring with policy reform, green finance, and regional cooperation. Fine particulate matter levels in the region decreased by about 44% between 2015 and 2023. The experience shows how sustained improvements can depend on coordinated action across sectors and administrative boundaries, rather than isolated measures. Regional cooperationRegional initiatives are also helping countries share data, coordinate policies and tackle pollution together. These include the ASEAN Haze Agreement, the Asia-Pacific Regional Action Programme on Air Pollution, and other regional partnerships. ADB is also supporting cooperation on transboundary air pollution in the Mekong Subregion and the Indo-Gangetic Plain and Himalayan Foothills. To address Southeast Asia’s recurring haze pollution, the ASEAN Investment Framework for Haze-Free Sustainable Land Management aims to mobilize $1.5 billion by 2030. The framework promotes sustainable land management and measures to reduce open burning. At the national level, Cambodia approved an investment framework in October 2026, identifying 15 projects requiring an estimated $690 million through 2035. The Lao PDR is also developing its own framework. Analysis suggests that measures in Southeast Asia such as reducing emissions from transport and industry, promoting cleaner cooking and preventing forest fires could reduce average exposure to fine particulate pollution by 50% to over 70% across many ASEAN countries by 2030. Uneven progressHowever, progress remains uneven. Cities and countries have different pollution sources, monitoring capacities, resources, and access to finance. They also differ in their capacity to implement and enforce policies, meaning that measures that work in one place cannot simply be replicated elsewhere. Many countries in the region have already established clean air policies. Turning these policies into sustained action requires stronger coordination, enforcement, and investment. Successful approaches need to be adapted to local conditions rather than simply copied from elsewhere. These issues were discussed during the BAQ Conference 2026, which brought together over 1,000 participants from 50 countries. Yet clean air receives only about 1% of international development finance. More public and private investment can help turn clean air priorities into projects that can be implemented at scale. Such investments can bring wider benefits, including better health, higher productivity, and more resilient economies. What Cities Can Do Experience across Asia and the Pacific points to four priorities to help sustain and extend air quality progress: Strengthen monitoring and data capabilities to identify pollution sources and track progress. Target the main local sources of pollution and turn policies into action. Increase public and private investment to scale up the measures that works. Enhance collaboration on pollution that extends beyond city or national borders. Together, these priorities can help cities sustain and extend air quality gains while adapting action to local conditions. Resources ADB Knowledge Events. 2026. Better Air Quality (BAQ) Conference 2026: Together for Clear Skies: Driving Action, Accelerating Investment. Clean Air Asia. 2023. Air Quality in Asia: Status and Trends 2023 Edition. Clean Air Fund. 2025. The State of Global Air Quality Funding 2025. London: Clean Air Fund. Health Effects Institute. 2025. State of Global Air 2025: A Report on Air Pollution and Its Role in the World’s Leading Causes of Death. United Nations Environment Programme. 2025. Clean Air and Climate Solutions for ASEAN. World Bank. 2022. The Global Health Cost of PM2.5 Air Pollution: A Case for Action Beyond 2021. International Development in Focus. Ask the Experts Karma Yangzom Principal Environment Specialist, Climate Change, Resilience, and Environment Cluster, Climate Change and Sustainable Development Department, Asian Development Bank Karma Yangzom coordinates ADB’s Environment Action Plan 2024–2030 and manages the Asia Clean Blue Skies Program. She leads initiatives on green infrastructure and has extensive experience managing environmental safeguards for infrastructure projects. Previously, she worked for WWF Bhutan. She holds a master’s degree from Yale University. Maria Katherina Patdu Environment Specialist, Climate Change and Sustainable Development, Asian Development Bank Maria Katherina “Kaye” Patdu helps implement ADB's Environment Action Plan aimed at promoting investments in nature and the environment. She also supports the Asia Clean Blue Skies Program, which aims to improve air quality through innovative projects and investments. Previously at UNEP, she coordinated regional clean air initiatives and national and city air quality action plans. Gary Haq Senior Research Associate, Stockholm Environment Institute Dr. Gary Haq is a human ecologist with over 20 years of experience in environmental policy and research. His work focuses on climate and clean air action, urban air pollution, air quality management, and sustainable and inclusive mobility across Africa, Asia, and Europe. Glynda Bathan-Baterina Deputy Executive Director, Clean Air Asia Glynda Bathan-Baterina is a lawyer with over 20 years of clean air policy and program development experience. She helped draft the Philippine Clean Air Act’s implementing rules, leads major clean fuel and vehicle initiatives in Asia, convenes the flagship Better Air Quality conferences, and serves on the World Economic Forum Global Future Council for Clean Air. Leave your question or comment in the section below: View the discussion thread.