This dataset consists of a vector layer (based on 1 by 1degree grid), of modelled ozone flux (POD1IAM, mmol m-2), The values per grid cell are Phytotoxic Ozone Dose above a threshold of y (y=1 nmol m−2 sec−1 in this case) for use in large-scale Integrated Assessment Modelling (IAM). The accumulated flux value per 90-day grassland growing season (mid-April to mid-July) is provided per grid cell, for the year 2018, across the UK and USA. Full details about this dataset can be found at https://doi.org/10.5285/afadb068-7e35-4271-bf07-0227d0a7a10f