OAK RIDGE, Tenn., Tiny airborne particles too small to see are more plentiful and may pose a greater health hazard than previously thought, says an Oak Ridge National Laboratory researcher studying airborne particles in the Great Smoky Mountains and beyond.
Recent evidence in scientific literature suggests that a relatively small increase in the concentration of particulate matter of 10 micrometers or less a tenth the diameter of a human hair -- results in a small but consistent increase in death rates and illnesses caused by impacts on the cardiopulmonary system.
Particles smaller than a couple of hundred nanometers generally come from manmade emission sources such as engine combustion. One micrometer is equal to 1,000 nanometers. Photochemical reactions of air pollutants in the atmosphere can also yield small particles that can undergo changes in size, shape and chemical composition.
Mengdawn Cheng of the Environmental Sciences Division is tracking and characterizing the "nanoparticles" in the Smokies and 29 other sites. He is also examining their toxicity in a process called "direct cell deposition," which was developed by his team. The technique differs from other approaches that involve collecting particles in a solution and then instilling the particles to animals.
"We believe that the instillation approach changes particle properties, size, shape and chemical composition, for example, and therefore we think such a practice does not allow us to study the toxicity of the right particles," Cheng said.
Chengs research also involves exposing cells directly to engine exhaust, which poses a challenge and had never been done. Cheng and colleagues are especially interested in the health effects resulting from exposure to nanoparticles typically produced by internal combustion and turbine engines and other sources.
Cheng and his co-workers exposed primed and normal human lung cells to synthetic particles and chemical
Contact: Ron Walli
DOE/Oak Ridge National Laboratory