[ ABSTRACT] AIM:To investigate the effect of hydrogen sulfide ( H2 S) on airway inflammation induced by ozone (O3) exposure and its mechanisms.METHODS:C57BL/6 mice (n=32) were randomly divided into control group, O3 group, NaHS+O3 group and NaHS group.The mice in O3 group and O3 +NaHS group were exposed to 2.14 mg/m3 O3 for 3 h on days 1, 3 and 5, while the mice in control group and NaHS group were exposed to filtered air .NaHS (14μmol/kg) was administered intraperitoneally to the mice in NaHS group and O 3 +NaHS group 30 min before each exposure .After the last exposure for 24 h, the airway responsiveness was determined , and bronchoalveolar lavage fluid ( BALF) was collected for counting inflammatory cells and measuring total protein concentration .The lung tissues were collected for observing the morphological changes with HE staining .The levels of interleukin-6 ( IL-6 ) , interleukin-8 ( IL-8 ) , malondialdehyde ( MDA) and NF-κB p65 protein in the lungs were determined .RESULTS: Compared with control group , the airway re-sponsiveness, inflammatory cells, protein concentration, inflammation score, levels of IL-6, IL-8, MDA and NF-κB p65 in O3 group increased significantly , but these in NaHS+O3 group decreased compared with O 3 group.CONCLUSION: The present findings suggest that H 2 S attenuates O3 induced airway inflammation by inhibiting NF-κB expression and preventing lipid peroxidation .