In occupational settings, the use of wearable ‘personal’ monitoring equipment following recognised testing methods allows an employee’s exposure to be surveyed more representatively.  It provides information on that employee’s exposure as they move between various locations during the course of a typical shift.

Workplace Exposure Limits (WELs) are set to help protect the health of workers.  They are concentration limits for hazardous substances in the air, averaged over a specified period of time, referred to as a time-weighted average (TWA).  The limits are legally binding as part of the Control of Substances Hazardous to Health Regulations 2002 (as amended).


Exposure to diesel engine exhaust emissions (DEEE) has long been suspected of causing ill health. GB rail is keen to expand its knowledge and understanding of occupational exposure to rail related emissions. 

This project was originally planned to cover five stations and depots, carrying out personal exposure monitoring of workers who could potentially be exposed to harmful diesel emissions. 

Due to the Covid-19 pandemic the scope was reduced to Birmingham New Street and Glasgow Queen Street stations and Crewe depot. Fortunately, the data generated from these locations is still considered to represent an accurate picture of the wide range of job roles and their personal exposure to DEEE.

Key Findings

The initial study was at Birmingham New Street, Crewe Depot and Glasgow Queen Street. These found that the personal exposures to diesel engine exhaust emissions (for staff involved in the study) are adequately controlled in relation to workplace exposure limits (WEL).

All personal exposures were significantly below the current WELs for the pollutants investigated during this study. However, some personal exposures to elemental carbon, nitrogen monoxide and carbon dioxide can be improved further (i.e. to bring the exposure to below 10% of the relevant WELs). 

Further data and additional surveys will help to build a more accurate picture of potential risk.