Comparison of hypervariable region II nucleotide sequences of mitochondrial DNA obtained from cord blood cells and saliva cells of the same individual at birth and after ten years revealed a few differences at the so-called mutation hot spots (three transitions and three indels within the C-tract). The personal identity of samples was proved by short tandem repeat profiling. Comparison of individuals living in two regions that differ by air pollution, however, did not reveal statistically significantly increased number of mutations in the population from the region of poorer environmental conditions, although indicating such tendency.