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From Conventional to Alternative Aviation Fuels: A Missed Opportunity to Minimise Adverse Occupational Health Effects?
School of Public Health & Social Work, Faculty of Health, Queensland University of Technology, Australia
The use of fossil fuels in aircraft over the last few decades has driven several studies on health effects due to occupational exposure. Relatively recently, alternative fuel types have emerged, but their implications on the health of workers exposed have not attracted proportional attention. This short communication shares the main messages from a review paper I co-authored with students from our postgraduate OSH courses at the Queensland University of Technology. The full version of the article can be found here: https://dx.doi.org/10.1021/acs.chas.0c00120.
1. The landscape
The availability and physical and chemical properties of kerosene-based aviation fuels have rendered them the choice for commercial and military aviation. However, kerosene-based fuels include toxic substances such as benzene, toluene, and n-hexane. As fuel is present at many stages in a long and complex chain of aviation processes, it is estimated over two million people annually are occupationally exposed to conventional aviation fuel, especially staff closer to refuelling operations, with an increasing number of reported health implications.
On the other hand, various reasons (e.g., diminishing oil supplies, environmental damage) led to the emergence of alternative fuels such as fuel cells, synthetic fuels, and biofuels. Those fuel types, which, to date, can be blended up to 50% with conventional fuel, are complex substances with biological and non-biological origins. They are mainly iso-paraffins and n-paraffins and contain phenols, alcohols, ketones, ether, acids and other complex substances. Exposure to these agents can still trigger health effects on workers during the various processes related to aviation fuel.
Occupational exposure to aviation fuels could be chronic or acute due to direct inhalation and dermal contact and dermal exposure to contaminated clothing/gloves, respiratory exposure to vapours, and incidental consumption of contaminated food/water. Although the precise likelihood of exposure per individual cannot be safely predicted subject to the wide variety of confounding factors (e.g., multiple body entry routes, technological advancements in fuel handling, risk control measures, changes in refuelling and maintenance practices), it cannot be neglected entirely.
2. Are alternative fuels safer for the health of workers?
Overall, our review of academic and industry literature sources indicates the comparative health effects of conventional and alternative aviation fuels remain unclear. Research into bio and synthetic fuels is limited, with only a little evidence to suggest a reduction in human health risks compared to kerosene-based fuels. The literature we reviewed reveals such research is restricted to animals and evaluations based on the composition of alternative fuels. Hence, although synthetic fuels offer economic and environmental sustainability for the future of aviation, they might pose similar risks to persons exposed to conventional aviation fuels.
Until the use of alternative fuels can subsequently be studied in occupational settings, the effects of alternative fuels on people cannot be wholly understood, and more studies must be performed. The elimination or minimisation of health risks should also be the aims of research and experimentation with alternative aviation fuels in addition to initiatives related to fire safety, aircraft performance, emissions, etc. Therefore, while addressing technical and environmental considerations, from an OSH perspective, it is also imperative to invest in minimising the presence of harmful substances in conventional and alternative aviation fuels and reducing fuel exposures. Notably, as respective guidelines and standards refer only to airborne concentrations and dermal exposure limits have not been defined, the aviation industry should not target compliance with exposure standards or legislation solely.
Thus, as science and technology advance, the question to be addressed is which fuel types are safer for both the environment and people while ensuring technical performance. The introduction of innovative types of aviation fuels can be an opportunity to tackle known occupational health problems and avoid generating new ones, especially of those most frequently exposed, such as refuellers, technicians and ground services staff in general.