Ventilation demand in a subway train.

The air quality in a subway train was studied to suggest optimal design criteria and operation conditions based on the ventilation demand by passengers. The CO2 emitted from the passengers was the tracer for this study. The CO2 bioeffluent from a human body was firstly quantified and used for the data analysis. Then the CO2 concentration was monitored in a subway train being operated. The number of passengers was also recorded with the tracer gas measurement over the selected subway route in Seoul.