Experimental and Panel Studies of Traffic, Ambient PM, and Black Carbon There is
evidence that inhaled ultrafine carbon particles, similar to theECcore of diesel soot, can pass
through the lung into the systemic circulation in humans.Nemmar et al. (2002) administered
99m Technetium-labeled carbon particles via inhalation to five healthy volunteers. There was
a rapid increase in radioactivity over the liver, and radioactivity counts increased in blood
samples and urine.