Data on atmospheric pollutant emissions from tourism activities was identified as a critical knowledge gap. Building an emissions inventory is a standard procedure that most countries perform for regulatory or research purposes. At a European level, these inventories are developed using the standard Nomenclature for Reporting (NFR sectors). However, none of the NFR are exclusively for tourism or explicitly include it. This paper presents a methodology to estimate the emissions from main touristic activities, focusing on Portugal as a case study. The emissions were distributed using tourism data as a proxy, namely the contribution of tourism to characteristic industries, as well as the nights spent in tourism establishments by non-residents. The proxy data was used to distribute emissions throughout the municipalities, using the national reported emissions data as a starting point. An analysis of the spatial distribution of tourism emissions was performed, highlighting that tourism has a significant impact on atmospheric emissions over specific areas (up to 40.1%), and contributing to areas where air pollution is already an environmental stress factor (urban centres of Porto and Lisbon). While this methodological framework was developed specifically for Portugal, it may be adapted to assess atmospheric pollutant emissions from tourism activities in other regions. Beyond the methodology proposed and the analysis of the results, other alternative methods to estimate emissions from the tourism sector are discussed and suggested.