Renewable Diesel "Not Necessarily a Silver Bullet" in Mining
By Kay Bechtold
On May 19 at AIHA Connect 2025, Rustin Reed, CIH, CSP, presented an overview of a study that examined exposures and health effects associated with the use of regular diesel compared with renewable diesel in a mining environment. According to Reed, who has more than 12 years of experience in mining and other industries, renewable diesel is derived from the same feedstocks as many types of biodiesel fuel but is “chemically different.” Manufacturers of renewable diesel claim that it reduces emissions compared to diesel fuel. Reed was involved with research conducted at the University of Arizona’s San Xavier Mining Laboratory, a student-run underground mining lab, using renewable diesel from a manufacturer based in Finland. The study yielded “mixed results,” Reed said, with outcomes “consistent with a lot of the literature you’ll find.” For example, renewable diesel did not reduce all emissions, and the researchers found that some acute health effects from exposure were decreased while others increased.
The study involved 24 subjects, most of whom were mining and public health students who Reed said did not have a history of exposure to industrial-scale diesel exhaust. Researchers used a crossover design, meaning that in 2021, they exposed the subjects first to exhaust from diesel fuel, then to exhaust from renewable diesel, and in 2022 they did the opposite “to control for any lingering effects from initial exposure,” Reed explained. The study procedure involved measuring subjects’ baseline or pre-exposure health effects before entering the underground mining laboratory, which had no ventilation and was “essentially the end of a 400-foot tube into the ground.” The subjects operated a Caterpillar skid steer for 45 minutes, then observed at a distance for 45 minutes. Immediately after subjects returned to the surface, the researchers measured their exhaled carbon monoxide before taking them to another location to take other measurements related to post-exposure health effects. The team also monitored exposures to respirable diesel particulate matter (DPM), nitrogen dioxide, and more.
In Reed’s experience, “the type of vehicle and the pollution control configurations on that vehicle will make a big difference” in exposures and health outcomes in the mining environment. And while the use of renewable diesel appears to reduce DPM—which is attractive because that’s what MSHA regulates, Reed noted—it is “not necessarily a silver bullet” due to the mixed results related to acute health effects and gaseous emissions. For example, some contaminants or health effects may increase with the use of renewable diesel.
“I think if you’re looking to reduce your DPM exposures to underground workers, renewable diesel may be an option for you, but you may not get the results you hope to get,” Reed told attendees.
Because this research involved a small sample size of 24 individuals and was conducted at a nonoperational mine, the results are “helpful but might not be generalizable to workers in a mine,” Reed said. He stressed that more research in this area is needed in both controlled and field environments.
Reed also acknowledged the shift toward electric vehicles in parts of the mining industry. While large mines may convert to electric vehicles and newer mines may begin using them from the start, Reed thinks that diesel exhaust exposures will continue to be a problem in the long term at small and medium-sized mines, as well as older operations.
“In 20 years, it will still be an issue—maybe not as much as it is today, but will still be an issue,” Reed said.
Kay Bechtold is managing editor of The Synergist.
Read more coverage of AIHA Connect 2025.
