First, PM concentrations on the platform increase as trains approach the station, and since dirty air from the tunnel is pushed onto the platform by the piston wind, the subway tunnels should be cleaned regularly. Thus, passengers should try to wait for trains near the middle of the platform. The staff working on the platform should regularly change working positions, so that the staff working at the middle position would regularly change places with the staff working at both ends of the platform to protect the health of the latter, and all of the staff working on the platform should take periodic breaks to reduce their pollution exposure.