This report summarizes the latest scientific knowledge on the links between exposure to air pollution and adverse health effects in children. It is intended to inform and motivate individual and collective action by health care professionals to prevent damage to children’s health from exposure to air pollution. Air pollution is a major environmental health threat. Exposure to fine particles in both the ambient environment and in the household causes about seven million premature deaths each year. Ambient air pollution alone imposes enormous costs on the global economy, amounting to more than US$ 5 trillion in total welfare losses in 2013. This public health crisis is receiving more attention, but one critical aspect is often overlooked: how air pollution affects children in uniquely damaging ways. Recent data released by the World Health Organization (WHO) show that air pollution has a vast and terrible impact on child health and survival. Globally, 93% of all children live in environments with air pollution levels above the WHO guidelines (see the full report, Air pollution and child health: prescribing clean air. More than one in every four deaths of children under 5 years of age is directly or indirectly related to environmental risks. Both ambient air pollution and household air pollution contribute to respiratory tract infections that resulted in 543 000 deaths in children under the age of 5 years in 2016.