The bad part was that burning high sulfur diesel fuel emitted a hell of a lot of carcinogenic diesel exhaust.
While railroads knew that diesel exhaust was carcinogenic back in the 1950’s, they still decided to prioritize the lubrication of their locomotive engines over the safety of the workers running them.
As a result, generations of railroad workers are being diagnosed with diesel-related cancers of the lungs, bladder, kidneys, throat, stomach and colon.
With the passage of the Clean Air Act, the EPA began to regulate sulfur levels in diesel fuel. From 2007 to 2014, the EPA dictated that low sulfur diesel fuel (500 ppm) be phased in for use on newer locomotives. By 2014, the EPA’s diesel standards required the newest locomotives to use ultra-low sulfur diesel (ULSD) which contains 15 ppm of sulfur.
Based mainly on availability, some railroads made the switch to ULSD before 2014. Unfortunately, many railroads who tried to use ULSD found that their old equipment was experiencing advanced corrosion due to the lack of lubricity with the ULSD fuel. As a result, some of those railroads switched back to the dirtier 500 ppm diesel fuel.
The EPA’s mandate for the railroads to switch to ULSD has been complicated. Railroads have resisted the changes to cleaner diesel fuel because that fuel is often harder on their locomotives, many of which are in service for 40 years.
So even today’s railroad workers operating older equipment using dirty fuel continue to suffer harmful diesel exposures.
It should be noted, however, that Tier 4 locomotives manufactured after 2015 are designed to burn cleaner fuel. These new locomotives burning ULSD should reduce the emissions of oxides of nitrogen, hydrocarbons, carbon monoxide and particulate matter. Tier 4 locomotives are equipped with high efficiency catalytic after treatment technology that could cut harmful emissions by as much as 90 percent compared to older model locomotives. Unfortunately, widespread introduction of these newer locomotives across a vast industry will take many years.