Food consumption contribution to nitrogen pollution of cities in Northern and Southern Europe

City-related nitrogen (N) loads pose a threat to the environment and alter its natural cycle. In this regard, citizen food consumption choices can have an essential impact on reducing N pollution. In this study, we present the first attempt to analyze the food N pollution of food consumed at city level. To this end, the nitrogen footprint (NF) concept is used, distinguishing between N released associated with consumption and N released associated with production. The food NF per capita and total food NF were obtained for six cities in Southern Europe (Athens, Lisbon, Marseille, Madrid, Rome, and Zagreb) and four cities in Northern Europe (Copenhagen, Helsinki, Oslo and Stockholm). Highly populated cities present a higher total food NF. However, the food NF per capita showed that Helsinki is the city with the highest N losses with 15.8 kg N released/cap/year. For both food NF, N losses from production accounted for an average of 94%. By adopting the recommendations of the healthy diet proposed by the World's Health Organization the average food NF is reduced by 31%. The findings of this study are relevant for reducing food consumer-induced N loads to the environment and promote sustainable development in cities.