Objective To study the potential harmful effects of brake-pad sourced particles.Methods Grind the brake pad particles or antimony sulfide particles.Mice were exposed brake pad or antimony sulfide particles by tracheal perfusion for 1 month.We observed pathological changes to the lungs,heart,and liver,and analyzed changes in peripheral blood macrophages and regulatory T cells(Tregs)via flow cytometry.Results After exposure,the deposition of foreign substances in the alveolar wall of mice was seen,with the obvious infiltration of inflammatory cells around blood vessels,which worsened with increasing particle concentration.Pathological changes,such as vascular inflammation and microthrombosis in the heart and hepatocyte swelling in the liver,were observed.Treg cells in peripheral blood decreased and macrophages increased in the antimony sulfide group and low-dose brake pad particles group,while the proportion of M2-type macrophages decreased,in the antimony sulfide group and low-dose brake pad particle group.Conclusions Exposure to brake pad particles and their component antimony sulfide has varying degrees of toxic effects on the lung,heart,and liver of mice and has an impact on the immune system,indicating the potential health hazards of brake-pad-derived air pollution.