Dust exposure in Munich public transportation: a comprehensive 4-year survey in buses and trams

Objectives: Published data obtained from outdoor stationary sampling statio ns cannot be applied directly to the exposure situation in vehicles. The ai m of this study, therefore, was to assess the dust exposure relevant to pas sengers and drivers in public buses and trams. Method: In the years 1993 to 1996, PM10 samples were taken during 201 journeys of typically 4 h duratio n on 14 routes (nine bus routes, five tramways) which were representative f or the overall Munich transportation system with respect to area characteri stics and traffic density. The concentrations of the samples were compared with those collected at the same time at sampling. stations of the Bavarian State Office for Environmental Protection (OEP. Dust exposure was continuo usly and synchronously recorded by means of a tyndallometric device. Traffi c and passenger density, weather conditions, special events, etc. were note d by our personnel, travelling on every journey. Results: The average PM10 dust concentration for all rides was 155 mu g/m(3) (single journey max. 686 mu g/m(3), min. 13 mu g/m(3)). Interior concentrations were 1.7 to 4.0 tim es above those collected at the static outdoor stations. We found only mino r associations between dust concentrations and traffic density or time of d ay. During several journeys continuous recording disclosed anomalies, depen dence on weather conditions and cyclic track characteristics. Conclusions: Interior PM10 particulate concentrations were comparable to those found els ewhere in truck drivers' cabs and are in the region of German regulative li mits established for the general population's long term outdoor exposure. I ndoor concentrations were well above the values found at stationary outdoor stations. Additional continuous recording of dust concentrations proved to be helpful in unveiling anomalies and dependencies on external effectors.