Ventilation demand in a subway train - based on CO2 bioeffluent from passengers.

The air quality in a subway-train was studied to suggest optimal design criteria and operationconditions based on the ventilation demand by passengers. The C02 emitted from thepassengers was the tracer for this study. The C02 bioeffluent from a human body was firstlyquantified and used for the data analysis. Then the C02 concentration was monitored in asubway-train being operated. The number of passenger was also recorded with the tracer gasmeasurement over the selected subway route in Seoul.From the measurement of human CO2 bioeffluent, it was found that the emission rate isdependent on the body position. Especially, a standing person generates more C02 by 29%than a sitting person. The correlation between the measured C02 concentrations and thepassenger numbers is significantly high. It implies that the passenger number could be aproper parameter for designing air-conditioning systems for subway-trains. Finally theintroduction of demand control, based on the passenger number, to maintain required airquality is suggested.