Indoor air quality control for improving passenger health in subway platforms using an outdoor air quality dependent ventilation system

Indoor air quality (IAQ) ventilation systems are widely used to control air pollutants in subway platforms. When outdoor air is heavily contaminated by particulate matters (PMs), it enters the subway platform through the ventilation system, resulting in the deterioration of platform IAQ and adverse effects on passenger health. In this study, a new IAQ ventilation system that takes into account the outdoor air quality used for ventilating platform is proposed to control the platform PM10 concentration. For this, the amount of PM10 that flows from the outdoors into the subway platform is considered a manipulated variable of the proposed ventilation system. The influence of the platform PM10 on passengers' health risk is evaluated using a comprehensive indoor air-quality index (CIAI). The CIAI level of platform PM10 is compared using the manual and proposed ventilation systems, where the manual system operates at fixed ventilation inverter frequency without regard to the outdoor air quality. Experimental results from an underground subway platform showed that the proposed ventilation system can improve the platform PM10 level, leading to the passengers' exposure to the reduced PM10 concentration (i.e., health risk reduction), and reduce the ventilation energy compared to the manual system by adjusting the ventilation inverter frequency and inflow of outdoor PM10 into the subway platform depending on the outdoor air quality.