Environmental standards for healthy ventilation in metros: Status, problems and prospects

Abstract

The metro is an indispensable transportation system in big cities and the primary commuting method for city residents. Ventilation primarily controls metro environmental health. The Chinese metro industry has gradually developed systematic codes, standards, and guidelines on environmental control and building design, drawing on excellent research and projects worldwide. This paper discusses the status, problems, and prospects of the Chinese standards related to metro ventilation. Healthy ventilation should prevent health risks according to the characteristics of vulnerable groups and the metro environment. This paper further discusses the threshold limit values, assessment methods, control standards, and design methods of building space and building equipment. Several challenges in metro environmental control are highlighted, including transient thermal comfort, hot and cold alternation, piston wind, air pollution, energy-saving, and control efficiency. The efficient-ventilated metro space requires an integrated design of piston ventilation, natural ventilation, and mechanical ventilation and coupled spatial forms with airflow organization. This can improve professional collaboration, environmental control efficiency, and energy-saving potential. Besides, insufficient epidemiological data and pathology studies on passengers’ health risks in metros limit the development of health standards and risk assessment methods that need further research.