NIR-II fluorescence imaging confirms the high retention of nanodots in the lungs and low accumulation in other major organs after inhalation administration, as well as the high biosafety of the melanin nanodots as they are metabolized out of the body over time via the liver and intestines. In addition, the melanin nanodots exhibited satisfactory antioxidant protection and inhibition of inflammatory cell infiltration in the lungs of HLI mouse models. Therefore, the melanin nanodots provide a potential and effective strategy for the treatment of HLI, showing great promise for application.