EDN1 and endothelial dysfunction: Systemic inflammation and increased concentrations of potent vasoconstrictors (i.e., endothelin-1, ET-1) are key features of exposure in MCMA children, as they correlate with cumulative exposures to fine particulate matter (PM) and outdoor exposure hours, and are a reflection of the sustained inflammation of the upper and lower respiratory tracts and endothelial dysfunction (Calderón-Garcidueñas et al., 2003, 2007, 2008b).