Lubrication oil appears to be an important yet little-recognized source of toxic particle emissions from motor vehicles -- even those fueled by clean-burning hydrogen, according to a joint study by government and academic researchers in Washington State and Minnesota.

Scientists have long recognized diesel-fueled vehicles as important sources of air pollution that can increase the risk of asthma, bronchitis, and other health problems. Most research, however, has focused on diesel soot, rather than emissions produced by lubrication oil.

In the new study, Arthur L. Miller and colleagues modified a truck diesel engine to run on clean-burning hydrogen instead of diesel fuel, allowing the researchers to focus solely on particle emissions from lubrication oil.



They found that the hydrogen-powered engine emitted higher levels of metal-rich particles than the diesel-fueled engine. Lubrication oil was the primary source of these increased emissions. Emission particles identified include calcium, phosphorous, zinc, magnesium, and iron nanoparticles, all of which have the potential to cause lung damage when inhaled over long periods, they say.

"This study's findings may increase current knowledge about the role of lubrication oil in particle-formation dynamics as engine technology improves and cleaner internal combustion engines are developed," the researchers state.

Article: "Role of Lubrication Oil in Particulate Emissions from a Hydrogen-Powered Internal Combustion Engine", Environmental Science & Technology.