Bus-exposure matrix, a tool to assess bus drivers' exposure to physicochemical hazards

Abstract

Overview

Swiss bus drivers face significant health challenges, including musculoskeletal disorders, fatigue, and stress. Compared to other workers, they also experience higher mortality rates from lung cancer and suicide. Despite these clear health risks, documentation of their occupational exposures remains limited.

Methodology

• Developed a bus-exposure matrix (BEM) to assess exposures to 10 types of physicochemical hazards in 705 bus models used in Switzerland since 1980.
• Compiled a thorough inventory and review of 50 technical characteristics per bus model.
• Identified 10 representative bus models to reflect the evolution of the Swiss bus fleet.
• Performed both static and dynamic exposure measurement campaigns in these representative buses.
• Used Integrated Nested Laplace Approximation (INLA) models to expand the findings across the entire fleet, relying on predictors and technical data based on directed acyclic graphs.

Application & Data Linkage

• Connected the BEM to occupational histories from a 2022 survey of Swiss bus drivers to estimate their exposure to various hazards.
• Assessed exposures annually from 1985 through 2022, estimating levels for
• PM10 ratio (-)
• Ultrafine particle ratio (-)
• Whole-body vibration (m/s²)
• Floor vibration (m/s²)
• Equivalent noise (dB(A))
• Peak noise (dB(C))
• High-frequency electric fields (V/m)
• Low-frequency magnetic fields (μT)
• Low-frequency electric fields (V/m)
• Air exchange rate (1/h)

Findings

• Peak noise, high-frequency, and low-frequency electric field exposures have increased over the years.
• PM10 ratio, ultrafine particles, equivalent noise, whole-body vibration, and air exchange rate exposures have decreased.

Conclusion

This pioneering development of a Bus-Exposure Matrix provides an innovative tool for retrospective exposure assessment. It establishes a methodology for evaluating occupational exposures, including electromagnetic fields, and highlights the need for continued research into their possible contribution to occupational health risks among bus drivers.

⚠ Important for EMF Safety: This study clearly documents exposure to electromagnetic fields (EMF) such as high- and low-frequency electric and magnetic fields among bus drivers, exposures which have been associated in the literature with increased health risks. Awareness and further research into mitigation strategies are recommended.