Satellite-based estimates of ambient air pollution and global variations in childhood asthma prevalence.

Background: The effect of ambient air pollution on global variations and trends in asthma prevalence is unclear.

Objectives: Our goal was to investigate community-level associations between asthma prevalence data from the International Study of Asthma and Allergies in Childhood (ISAAC) and satellite-based estimates of particulate matter with aerodynamic diameter < 2.5 µm (PM₂.