When exposed to Hamilton air (but not HEPA filtered air) for 10 weeks (followed by 6-weeks recovery in the lab), the mice had a 1.6-fold increase in sperm mutation frequency and an increase in global methylation of germline DNA. From the article:
"We have demonstrated that exposure of inbred mice to particulate air pollution near two integrated steel mills and a major highway caused tandem repeat DNA mutation and hypermethylation in spermatogonial stem cells. [...] The overall implications of these findings for the health of humans are unclear. Heritable mutation, germ-line DNA damage and epigenetic modifications have the potential to affect disease incidence in the descendents of exposed individuals. In addition to its potential importance in the maintenance of genome stability, appropriate methylation of DNA is critical for imprinting, regulation of gene expression, mammalian development, and disease."
No word yet on whether any of these mutations conferred super-powers.