Occupational Exposure to Diesel Exhaust in Bus Drivers in the New York Metropolitan Area

BACKGROUND AND AIM: Exposure to diesel exhaust (DE) has been associated with adverse respiratory health outcomes and bus drivers could be at significant risk. We leveraged exposure data collected from real-time personal monitoring and geospatial location information to identify the factors influencing DE exposure in New York bus drivers. METHODS: DE exposure was estimated via black carbon (BC; a component of DE) measurements recorded using a micro-Aethalometer (microAeth®Model-AE51) every minute over six 24-hour periods in four bus drivers during September-October 2014. Driving routes originated from two Westchester bus depots and traversed lower Westchester. Each driver’s location was continuously recorded every minute using a global positioning system (GPS) device. Information on fuel type, smoking status, worker activities, and meteorological variables were collected. Road density indices were calculated based on an 100-meter buffer. We performed multivariable-adjusted regression models to assess the factors associated with BC levels. RESULTS: BC data were collected for a total of 2682 working minutes and 4328 non-working minutes. Overall median BC level was 578 ng/m3 (IQR: 189-1487 ng/m3) [working hours: 1166 (612-2168) ng/m3; non-working hours: 351 (132-860) ng/m3]. Multivariable-adjusted models predicted that compared to times working in office, workers were on average exposed to an additional 1403.5 ng/m3 and 2150.4 ng/m3 of BC when they were in the depot yard and driving the bus, respectively. Driving a diesel-powered vehicle was associated with 2.7-fold increase in BC levels compared to gasoline-powered. For every 10% increase in the sum of road length index, BC level increased by 19% (95%CI=15-24%). Further, for every 10% increase in average speed, BC level increased by 20% (95%CI=17-23%). CONCLUSIONS: Driving a diesel-powered vehicle presented significantly more BC exposure comparing to gasoline-powered vehicle. Roadway density and driving speed contributed to elevated BC levels. KEYWORDS:diesel, transportation, bus driver, occupational exposure