In this study we analysed two time series of surface ozone recorded in Tenerife: one in a marine environment (Aguere, in the marine boundary layer at 580 m.a.s.l.) and other in the free troposphere (Izaña, above the trade wind inversion layer at 2367 m.a.s.l.). We performed a systematic 4-year analysis of ozone, backtrajectories and synoptic charts. The transport pathways of ozone for different O3 percentile (Pth) ranges were determined. At both sites, low ozone levels (<50 Pth, but mainly those <25 Pth) are mainly associated with transport from low altitudes over the Central North Atlantic and North Africa. Increasing ozone levels from 50 to 100 Pth are associated with a reinforcement of: (a) a northern transport pathway (off Portuguese coast) from the North Atlantic mid-latitudes and Western Europe to Aguere, and (b) a characteristic N–NW transport pathway to Izaña. At both sites, these increasing ozone levels are associated with transport pathways showing subsidence typically from 3 to 5 km.a.s.l. At Aguere, high ozone events (>90 Pth) occur from March to June, and are mainly associated with a subsiding transport pathway from the western side of lows developing over Western/Central Europe and the North Atlantic mid-latitudes. At Izaña, high ozone events (>90 Pth) occur from April to August, and are associated with subsidence at the western edge of lows over the North Atlantic (very frequently at the W or SW of the Iberian Peninsula). The results of this study highlight the importance of the downward transport of ozone. High ozone events under meteorological scenarios classically associated with stratospheric intrusions have been recorded every year at the two sites. However, with our results we cannot ultimately determine if these high ozone events are caused by downward transport from the upper troposphere/lower stratosphere, or by lifting of continental ozone pollution and subsequent subsidence. The occurrence of high ozone events (>90 Pth) at Izaña and not in Aguere during summer (when the trade wind inversion located between these sites reaches its strongest stage) is an evidence of the importance of the ozone downward supply from mid-upper troposphere in this region.