It is at this critical moment for the prevention and control of the COVID-19 pandemic that this proposal has happened. Since mid-February 2020, as work resumption took place across Shanghai’s enterprises and institutions, the number of Shanghai Metro passengers has continued to rise. With annual passengers of Shanghai Metro Station amounting to 10.65 million, the growing number of passengers will inevitably increase the risk of cross-infections inside the station. To maximize the air quantity, an effective way is to remove pollutants and dilute the possible concentration of pollutants, which will reduce the possibility of cross-infection. However, the maximum output of fresh air in standard subway stations is currently limited to only two original air supply units, or a total of 36000 m3 / h. The hygiene design standard is 30m3 / h, while the fresh air volume can only accommodate 1200 people per hour to go through the station, which is far lower than the average of about 1-2 million people per hour in and out of the station.
     Under such conditions, it is proposed by Prof. Wang and her team members that there is the need to make full use of the natural power of the pressure difference caused by the train stops and departures, which will bring outdoor fresh air into the station. When the train leaves, the four screen doors at both ends of the subway station platform shall be delayed for 1 minute. This proposal introduces an outdoor fresh air volume (outdoor pollution-free environment) which reaches about 33653m3 / h on average, accounting for 94% of the station’s maximum fresh air volume.

 (1) During the period of pandemic prevention and control, this proposal can introduce fresh air volume of about 33653 m3 / h through the entrance and exit of the subway, accounting for 94% of the maximum fresh air volume for existing stations, which effectively reduces the concentration and content of station air pollutants and significantly lowers the risk of cross infection and protects the health and safety of passengers and staff.

 (2) Simple, easy and practical to implement, this proposal requires minor changes in the opening and closing of some screen doors.

 (3) Without consuming other energy sources, this proposal makes full use of the natural sources of train operation and has obvious advantages for energy saving.
The research results of this program are, not only useful during the period of pandemic prevention and control, but also helpful to environmental control ventilation of subway stations when outdoor air quality and temperature are agreeable. Making full use of natural energy to significantly increase the fresh air volume in subway stations, this proposal has both practical and theoretical value.
         A Brief Introduction to Prof. Wang Lihui
       Professor Wang Lihui, Deputy Dean of the School of Environment and Architecture is sensitive to such underground environment issues as subway environment, has chaired programs on the subway thermal environment and energy conservation, including at the General Program of National Natural Science Foundation of China and at the Youth Program of National Natural Science Foundation of China. She is used to combining scientific research with demands for industrial development, and maintains long-term project partnerships with: Shanghai Metro Shentong Group Technology Center, Shanghai Tunnel Engineering & Rail Transit Design and Research Institute, Shanghai Urban Construction Design & Research Institute, and other Shanghai metro operating companies. As the first author, she has published over 80 articles in SCI 1, EI periodicals and Peking University core journals, and has more than 10 national invention patents, utility model patents and software copyrights.
      Noteworthy, Professor Wang integrates scientific research into her teaching, and has won the second prize of Shanghai Teaching Achievements, chaired one program of Shanghai Excellent Courses, and has gained one program of a special prize of Teaching Achievements of USST.