Monitoring ozone abundance throughout the entire atmospheric column is of critical importance for planetary health. At the surface, ozone is one of the so-called “criteria” air pollutants regulated by environmental agencies in most countries. Furthermore, tropospheric ozone is a short-lived climate forcer and the third most powerful greenhouse gas after methane and carbon dioxide. In contrast, stratospheric ozone is vital because it shields Earth from harmful ultraviolet radiation.

At Universidad San Francisco de Quito (USFQ) in Ecuador, we have coordinated efforts to monitor ozone in situ across the entire atmospheric column from our Atmospheric Monitoring Stations in Quito (EMA UIO, Spanish acronym) and the Galápagos Islands (EMA SCY, San Cristóbal Island). In this work, we present insights gained from over a decade of observations along the Andes–Galápagos transect. First, we discuss tropospheric ozone in Quito and how measurements combined with estimation methods are used to understand ozone production mechanisms and chemical regimes. In addition, we present surface ozone measurements in the Galápagos Islands, where a clean background atmosphere is reflected in diurnal ozone profiles that contrast with the urban signature in Quito. We then examine ozone sounding data from both locations and compare the morphology of their vertical profiles. Previous studies show that stratospheric ozone levels are consistent between the two sites, whereas tropospheric ozone differs. Specifically, the tropospheric ozone column over Quito is lower than in the Galapagos, partly due to high altitude, although relatively low surface ozone levels also contribute. Finally, we discuss the challenges of maintaining long-term observations and outline future work.