For the 21.8 million residents in Metropolitan Mexico City (MMC) regularly exposed to fine PM (PM2.5) above the US 12 μg/m3 annual average standard and to high concentrations of highly toxic NPs (42, 43), the issue is how to protect millions of urbanites from the early development and progression of AD, PD, and TDP43 starting in childhood. The gene discussed is TARDBP; the disease is Parkinson disease.