Case Study: Enhancing Occupational Health and Safety: A Case Study on Diesel Fume Monitoring and Mitigation

This case study examines a substantial aspect of occupational health and safety in the context of railway depot maintenance operations in England. The overarching focus is on a railway company that operates passenger train services extensively across the region, acting as a pivotal component in the transportation infrastructure. Given the indispensability of the railway system for daily commuting and its significant impact on local economies, a robust and regular maintenance regime is imperative for ensuring its uninterrupted operation.

Depot maintenance operatives fulfil a vital role in the servicing and upkeep of the railway engines, undertaking both routine and emergent maintenance tasks. However, this crucial job role is associated with several occupational hazards, among which exposure to diesel exhaust fumes is particularly significant.

Diesel exhaust fumes represent a complex admixture of gases and particulates, primarily constituting carbon dioxide, nitrogen oxides, sulphur oxides, volatile organic compounds, and particulate matter. The latter are exceedingly small particles that can be effortlessly inhaled into the human respiratory system. Chronic exposure to such elements can pose substantial health risks to the maintenance personnel, thereby making diesel exhaust fume exposure monitoring an absolute necessity.

The objective of this case study is to elaborate on the significance of such exposure monitoring, outlining its potential contribution to enhancing the safety and well-being of depot maintenance operatives. It also emphasises the importance of industrial hygiene practices in ensuring a safe and healthful working environment in such high-risk settings.

Our Method

In this occupational health and safety case study, our methodology involved the identification and selection of suitable analytical targets to evaluate the exposure to diesel exhaust fumes experienced by railway depot maintenance operatives. Given the complex composition of these fumes, we opted for a blend of specific indicators including Nitrogen Oxides (NO and NO2), Carbon Monoxide (CO), Carbon Dioxide (CO2), and both Elemental Carbon (EC) and Organic Carbon (OC).

To ensure accurate measurements and adherence to recognized standards, we applied established analytical methods. These included the application of NIOSH 4050 for EC and OC, NIOSH 6014 for Nitrogen Oxides, and data logging devices for Carbon Monoxide and Dioxide. Each of these techniques is designed to accurately measure exposure to the specific substance in question, offering reliable data for our analysis.

For defining exposure limits, we adopted the values of 0.96mg/m³ for Nitrogen Dioxide, 2.5mg/m³ for Nitrogen Monoxide, and 23mg/m³ for Carbon Monoxide. While there is currently no assigned UK Workplace Exposure Limit (WEL) for respirable elemental carbon, it is internationally recognized as a suitable marker for the presence of Diesel Engine Exhaust Emissions (DEEE).
 
The significance of the DEEE was underscored by the Directive (EU) 2019/130, amending Directive 2004/37/EC, which was transposed into UK legislation on 21st February 2021. The directive introduced a new exposure limit for DEEEs, measured as elemental carbon, set at 0.05mg/m³ for an eight-hour time-weighted average, to be implemented by 21st February 2023.

In the interim, we adopted the German TRK exposure limit for respirable elemental carbon, which stands at 0.1mg/m³ over an eight-hour period. In scenarios where the OC concentration is greater than EC concentration, a limit of 0.15mg/m³ total carbon (TC) was applied, in accordance with additional guidance sourced from The Annals of Occupational Hygiene.

This meticulous methodological framework was devised to ensure comprehensive monitoring and evaluation of the depot maintenance operatives' exposure to diesel exhaust fumes, with the goal of protecting their health and wellbeing in their essential role.
 

Observations

Our site observations revealed an operation split into numerous shifts across the week, with employees rotating through a variety of schedules. The longest shift times and overall exposure times were considered in this assessment.

The first group under assessment, namely the Train Maintenance Shed (TMS) Operatives, consisted of up to 20 individuals engaged in various servicing, cleaning, and maintenance tasks. Exposure to components associated with diesel emissions was most likely during engine movements for testing purposes. Night shifts, exclusively servicing diesel trains, were likely to have higher diesel emissions exposure compared to day shifts. The second group, Train Servicing Shed (TSS), again included up to 20 employees engaged in similar tasks as the TMS operatives. They were also likely to be exposed to diesel emissions during testing.

Across both groups, protective personal equipment (PPE) such as nitrile gloves, long-sleeve personal garments, and high-vis overalls were commonly worn. Clear signage, warning alarms for moving trains, and the availability of cleaners during the day shifts contributed to the maintenance of a safe working environment.

Furthermore, employees were enrolled in regular health surveillance, including lung capacity checks, dermal checks, audiometry, eye function checks, and vibration damage checks. Regular toolbox talks kept employees updated on safety regulations, and additional monitoring was introduced following maintenance issues identified during the observation period.

Findings

Our air monitoring results indicated that employee exposure to Nitrogen Dioxide and Nitrogen Monoxide remained below their respective workplace exposure limits (WELs). However, there were instances where exposure levels of elemental and/or total carbon came close to, or exceeded, the WELs. Specifically, in three instances, the exposure to elemental and organic carbon surpassed the workplace exposure limit.

When we look at the percentage of samples across different exposure categories, we find that 6% of the Elemental Carbon samples exceeded the WEL, while 3% were significant but did not exceed the limit, and 91% were not significant. In the case of Total Carbon, 8% of the samples exceeded the WEL, another 8% were significant but didn't exceed, and 84% were not significant. For Nitrogen Dioxide and Nitrogen Monoxide, none of the samples were significant or exceeded the WELs, with 100% falling into the 'Not Significant' category.

The exposure to nitrogen dioxide, nitrogen monoxide, and total elemental and organic carbon is deemed significant as the personal exposure exceeds 50% of the workplace exposure limit. Because of this, it's strongly recommended to implement the suggested actions to reduce risk.
 

Recommendations

Based on the data and observations from the assessment, we highly recommend taking a multifaceted approach to mitigating the risks identified in the workplace. It is strongly recommended to reduce the personal exposure of employees to total elemental or organic carbon below 50% of the WEL. This likely involves improving the existing safety protocols, increasing the use of personal protective equipment, enhancing the ventilation systems, or even making changes in operational processes.

Firstly, it is critical to address the high level of personal exposure to diesel particulates. One feasible measure to curb this is the introduction of filters attached to tailpipes. These filters would help significantly reduce exposure to harmful particulates, thereby enhancing the safety of the employees.

Parallel to this, an emphasis on routine inspection and maintenance is recommended. Ensuring that engines are regularly serviced and well maintained can greatly reduce the emission of harmful substances. Particularly, keeping catalytic converters in optimal condition can significantly decrease the levels of nitrogen dioxide and monoxide.

The deployment of Local Exhaust Ventilation (LEV) systems could also prove beneficial. Installation of tailpipe exhaust extraction systems can aid in mitigating the exposure to harmful fumes. However, it's crucial that these LEV systems are thoroughly examined and tested in line with the Control of Substances Hazardous to Health (COSHH) Regulation 9 to ensure their efficiency and safety.
 
Improving general ventilation systems is another key consideration. This could be achieved by installing workplace air extraction fans and air vents in the walls and ceiling to promote natural ventilation. Whenever possible, doors and windows should be kept open, especially when engines are running to disperse fumes.

As part of a proactive health strategy, it's recommended to implement a suitable dermatological health surveillance program for personnel who regularly handle fuels. This can help identify any potential skin conditions such as dermatitis or allergies in their early stages and take the necessary actions.

Moreover, employees should be encouraged to turn off vehicle engines when they're not needed to limit unnecessary exposure to diesel fumes.

Additionally, given that skin exposure to diesel fuel may cause dermatitis and skin allergies, operatives should be provided with appropriate gloves and work clothing. Adopting a high standard of personal hygiene is paramount. To support this, employees should have access to suitable washing facilities and should be encouraged to use the mess room for eating and drinking to limit potential exposure to harmful substances.

Value delivered

Throughout our engagement, we have delivered substantial value to our client by establishing a comprehensive understanding of the occupational health and safety risks present in their workplace. We conducted meticulous site observations and air monitoring to assess the levels of potentially hazardous substances. Our efforts have not only shed light on immediate risks, but have also provided our client with a detailed understanding of the health implications for their employees in both short and long-term scenarios.

Furthermore, our evidence-based recommendations provide a roadmap for mitigating these risks, improving workplace safety, and ensuring regulatory compliance. By implementing these measures, our client is empowered to create a safer and healthier working environment, which in turn can enhance employee morale, productivity, and retention.

The value we have delivered extends beyond the immediate scope of the project. Through fostering an informed awareness of health and safety issues, we have helped to instil a culture of safety within the organisation. This proactive approach not only reduces the risk of harm to employees but also mitigates potential legal and financial repercussions associated with workplace accidents or chronic health issues. In doing so, our client can ensure the long-term sustainability of their operations, demonstrating their commitment to the well-being of their staff, and enhancing their reputation as a responsible employer.