Ozone was measured with a 2B Technology ozone monitor (model 205). The concentration is reported as a mixing ratio in parts per billion [ppb], at 60 seconds average. Ozone is a trace gas that can be formed directly in the troposphere (the most important formation pathway is the photochemical reaction of volatile organic compounds with NO,,x,,) or entrained from the stratosphere where it is formed directly from the reaction of molecular oxygen with UV light. Ozone is an important oxidant in the atmosphere and participate in several chemical reactions. Measurements were performed on the 4th deck of icebreaker Oden during August and September 2018 along the track of the Arctic Ocean 2018 expedition.