8292094 Occupational exposure to diesel engine exhaust emissions among bicycle couriers operating in the city of Milan, Italy

<h3>Introduction</h3> Due to prolonged and direct contact with vehicle traffic, exposure to diesel engine exhaust emissions poses an occupational risk for workers in the logistics sector. Bicycle couriers, a growing and increasingly recognized workforce in urban environments, are particularly at risk due to the high ventilation rate and physical effort required by their job. <h3>Objective</h3> To assess the exposure of bicycle couriers to diesel exhaust emissions during last-mile delivery operations in the city of Milan. <h3>Material and Methods</h3> Four AE51 micro-aethalometers (Aethlabs) with high temporal resolution (1 s) were used to measure equivalent black carbon (eBC), a tracer of diesel engine emissions. Devices were mounted on four cargo bikes, with sampling tubes fixed to the handlebars. Exposure was monitored over all four seasons, from autumn 2023 to summer 2024, during weekday working hours (9:00–18:00). Instruments were compared regularly during the campaign with a stationary AE33 aethalometer (Magee Scientific) located in traffic-free background sites. <h3>Results and Conclusions</h3> This abstract presents preliminary results for the winter season only, considered a worst-case scenario due to typically higher pollution levels. Average BC exposure during work shifts was 4.1 µg/m³, double the background level (2.1 µg/m³) and comparable to the traffic-site reference (4.0 µg/m³). The highest daily average was 6.1 µg/m³. Morning shifts (5.0 µg/m³, max 9.8 µg/m³) showed higher exposure than afternoon shifts (3.2 µg/m³, max 8.2 µg/m³), with peak values from 9:00 to 10:00. Intra-day variability was high (average CV% 33%, max 42%), suggesting a role of routes and timing. While eBC levels remained below the occupational limit defined for elemental carbon (a closely related marker), the findings still highlight a relevant professional risk. Further analysis will model exposure, focusing on spatial and temporal determinants such as urban layout, routes, road types, and meteorological factors.