Measurement and analysis of the air quality within a high-speed train carriage in a region of Southwest China

Abstract

To investigate the air quality status and identify factors influencing air pollution, data on CO2, formaldehyde, PM2.5, PM10, temperature, and humidity were measured in a high-speed train carriage of the Changsha-Zhuzhou intercity in southwest China. In the test section, CO2, formaldehyde, relative humidity, and temperature exceeded the standard levels, and their compliance rates were 84%, 96%, 84%, and 76%, respectively. Then the influencing factors of pollutants were analyzed from three aspects: driving environment, the number of passengers, and relative humidity. Results show that the percentage of PM2.5 to PM10 in tunnel environments was higher; the increase in the number of passengers led to the elevation of CO2 concentration in the carriage, while only in the ground environment, the number of passengers significantly correlated with particulate matter; the increase in relative humidity promotes the production and release of particulate matter and formaldehyde. Finally, fitting relationships between relative humidity and formaldehyde, as well as the number of passengers and CO2 were established to predict the air quality status. It indicated that when the relative humidity of the carriage is less than 73%, the formaldehyde solubility was easy to exceed standards, and when the number of passengers was greater than 70, the CO2 was easy to exceed standards.