Recently, we investigated that the acceptable concentration (0.1 ppm) of ozone exposure significantly influenced the percutaneous oxygen saturation (SpO2) in a mouse model of acute lung injury (ALI). However, ozone is widely used from hospitals to homes because of its strong sterilizing power and low cost. Therefore, ozone safety levels should also be considered for patients with respiratory diseases such as ALI and asthma. This study examined the effects of ozone exposure 0.1 or below ppm in asthmatic and ALI mice to determine the "real" safety concentration. Asthmatic mice were created by repeated intranasal administration of dermatophagoides farina to BALB/c female mice. Also, ALI mice were generated by intranasal administration of LPS to female BALB/c mice. Ozone exposures (0.1, 0.05, and 0.01 ppm) were performed for 5 consecutive days before sample collection. SpO2 was monitored 24 hours after allergen or LPS administration, and samples were collected immediately after. Hilar lymph node, lung, and alveolar lavage fluid were collected to determine the pro-inflammatory and cytotoxic responses. A 0.1 ppm ozone exposure significantly reduced the SpO2 level in asthma and ALI models, whereas 0.05 and 0.01 ppm exposure did not impact. Histological abnormalities and gene expression of pro-inflammatory cytokines were also significantly increased by 0.1 ppm ozone gas exposure in both models; however, there were no changes in 0.05 and 0.01 ppm ozone treatment. Our findings imply that ozone safety levels can influence the lung and immune function in the Asthma and ALI model mouse.
