Summary: This evidence into action brief summarises the state of research on the topic of urban air pollution in low- and middle-income countries and its impacts on children, and proposes ideas for action. Air pollution is a major global health challenge to which children are particularly vulnerable. In this briefing, the authors summarise the literature on this topic, focusing on low- and middle-income countries (LMICs). There are indoor and outdoor sources of air pollution and these pollutants can remain in the local area or be transported vast distances. Therefore, to reduce air pollution emissions and exposure to pollution, action is needed at local, national and international levels. In many cases, these actions can contribute to achieving multiple other sustainable development goals, including climate change mitigation. An integrated approach to action is needed, involving collaboration with community members, planners and policymakers.

• Invest in regulatory air pollution monitoring stations and provide training on data management and how to interpret the data. This will highlight the extent of pollution in places where monitoring is lacking.

• Support the development of air quality management systems (including air-quality regulations and standards on emissions) to monitor and reduce air pollution, particularly in urban areas.

• Develop citizen science monitoring programmes to fill the gaps in monitoring. Scientists and community members should work together to answer scientific questions, collect data and co-design awareness-raising campaigns at community level.

• Work with governments to integrate air pollution into climate change targets. Many sources of greenhouse gases are also sources of air pollutants. LMICS can increase their mitigation ambitions, meet international targets and achieve local development benefits through improved air quality.