Measurements of particles <10μm (PM10) and particle-bound polycyclic aromatic hydrocarbons (pPAH) were performed in different passenger train coaches between Zürich and Berne, the most busy intercity connection in Switzerland. All trains are electrified and the indoor air quality is regulated by a mechanical ventilation system. In the smoker sections, pPAH levels were on average about 250ngm−3, PM10 levels about 950μgm−3. In the non-smoker section, pPAH levels were about 45ngm−3 and PM10 levels about 210μgm−3. Our observations suggest that smoking is the most important source of pPAH and PM10. The spatial variation within the coaches indicates that pPAHs spread out from the smoker compartments into the non-smoker compartments. For PM10, resuspended material may also be a source of airborne PM10 but the contribution within this non-stop connection with most of the passengers being seated all the time was probably small. The influence of outdoor PM10 and pPAH on indoor levels was negligible. Both pollutants, pPAH and PM10 were largely elevated in the smoker as well as in the non-smoker compartments. Despite this fact, a questionnaire on the quality of travelling showed that most of the passengers felt well and only a small proportion felt uneasy.