HDAC6 and childhood onset asthma: Accumulating studies have reported a role for let‐7i‐5p in multiple diseases.[18, 19, 20] For example, the low expression of let‐7i‐5p caused by histone deacetylase 6 (HDAC6) directly increased expression levels of the target gene TSP1 levels, thereby suppressing antiphagocytic and neoplastic behaviors of hepatocellular carcinoma.[21] However, the biological function of let‐7i‐5p in PM2.5‐induced childhood asthma is unclear.