Tregs exposed to phenanthrene show decreased TGF‐β and IL‐10 and increased IL‐4, IL‐13, (p)STAT6 and GATA‐3.61 It has recently been shown that repeated exposure to air pollution and to noxious molecules may promote AD.1, 2, 3, 4 Thus, pollutants may contribute to AD also via their ability to affect Treg populations, especially by impeding their immunosuppressive capacity by causing them to redifferentiate into Th‐like cells that produce proinflammatory cytokines. Here, IL4 is linked to Alzheimer disease.