It is also worth noting that after the subway station has been built, many characteristics of the station cannot be easily changed. However, our study provided some consistent findings that suggest ways to minimize health damage caused by air pollution in the subway. 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. The effectiveness of this approach was observed who reported lower PM levels at subway stations after washing the tracks, floor, and walls of the tunnels. Second, during our first measurement phase, we found that the average PM2.5 and PM1.0 concentrations on the platform were both nearly 1.6 times the values inside the train. Therefore, passengers should minimize the duration of their stay on the platform. Most importantly, the effect of the piston wind differed among the positions on the platform. At the Songyuan Road station, the average PM2.5 concentration at both ends of the platform was about 15% greater than that at the middle position. At the Jiao Tong University station, the average PM2.5 concentration at both ends of the platform was around 18.5% greater than that at the middle position. 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. One caveat is that in the subway systems of some other cities around the world, the piston effect was not always stronger at both ends of the platform than in the middle. The strength of the piston wind effects at different positions depends on many factors, such as the presence or absence of platform screen doors, the location of the access points, and the condition of the ventilation system