An electron spin resonance study of free radicals in black dust deposited in human lungs

An Electron Spin Resonance measurement was conducted on black dust deposited in autopsied human lungs. Free radicals were detected in all specimens examined, and the spectra indicated the presence of two types of radicals, both of which are apparently singlet lines. The amount of the respective component differed from sample to sample. The component with the narrower width, 2.7 G, and the smaller g factor, 2.0025, is attributable to carbon radicals associated with the combustion of hydrocarbons, and especially its relevance to the experience of smoking was inferred. The other component, with a width of about 10 G and g factor fo 2.0037, was found to be more common among the specimens. The assignment of the latter component is not very clear, but an oxygen-related radical is a possible candidate.