The emissions were recorded on several nonpermissable heavy duty diesel locomotives and light duty service vehicles, the agency said, while mines were working to remain in compliance with diesel particulate matter outlines, formally known as 30 CFR Part 72 Subpart D.
“MSHA field investigation/evaluation has determined that oversized platinum-based diesel particulate filters were installed on the heavy-duty equipment,” MSHA said in the alert.
“The light-duty equipment which did not have a DPF, but did have a diesel oxidation catalyst, was determined to have engine operational problems.”
According to MSHA, the symptoms of NO2 overexposure include eye, nose and throat irritation, cough or chronic bronchitis, breathing difficulties, chest pain, pulmonary edema and rapid heartbeat.
It also referred to a program information bulletin it issued previously, PIB P11-38, which outlined the potential health hazards caused by platinum-based catalyzed diesel particulate matter exhaust filters. In it, the agency identified the filters as a source of increased concentration generations.
“The oversized DPFs installed on these locomotives have lower percentages of platinum than those addressed in the bulletin, but they have a similar problem of generating increased NO2 concentrations due to their physical [larger] size,” the alert says.
“An oversized DPF was selected to avoid excessive backpressure on the MSHA approved engine. The locomotive’s exhaust system was long and included several 90 degree bends which created backpressure near the maximum allowable limit without the DPF installed.”
MSHA recommended an evaluation process to mines to determine whether a catalyzed filter, DOC or engine operational setting were causing a concentration increase that could take the operation over the NO2 threshold limit value of 5 parts per million.
First, the machine should be operated in an entry that provides at least the engine’s name plate air quality, but not more than an additional 20%.
The unit should also be operated under load.
Finally, the agency said, operators should remotely monitor NO2 levels in the diluted exhaust stream to prevent possible overexposure.
“The NO2 concentration should not exceed 5ppm when tested in order to demonstrate compliance with the engine approval,” officials said.
MSHA said its representatives would be available to assist mines with setting up the test, but reminded operators to contact the manufacturer of the equipment of DPF for assistance in selecting the appropriate DPF.
Additionally, the equipment producer should be contacted to help diagnose engine operation parameters that could possibly produce high NO2 levels.
Mines with any questions on the alert can contact their district manager.
MSHA urged that all instances of increased emissions from diesel equipment be reported to the operation’s respective DM.
