Aims We constantly interact with our surrounding microbiome, including the micro-organisms present in highly populated public places. However, data on everyday exposure to background levels of micro-organisms are limited. To address this, bacteria and fungi were collected and enumerated in settled dust from railway stations. Methods and ResultsConclusionsSamples were collected weekly for 52weeks, from up to three pre-determined surfaces in each of 17 railway stations in England and Scotland. Trained staff at each station took surface wipes, sending them to the laboratory for culture-based analysis for total bacteria and fungi. Maximum yields of bacteria at the stations were 10(7)-10(8) colony forming units (CFU) per cm(2), and 10(4)-10(5) CFU per cm(2) for fungi. There was evidence of seasonal trends, with bacterial numbers rising from spring through to winter, while fungal numbers peaked in autumn. Microbial numbers were similar in samples taken at the same time at a given station. Influences on contamination levels were likely to be a combination of passenger numbers and station layout, with dust generated from construction work also contributing. Significance and Impact of the StudyA baseline of typical human exposure to micro-organisms in public transport hubs was established through the generation of a comprehensive database.