Objective To investigate the status of air quality in Shanghai subway system station so as to provide scientific basis for the establishment of relevant hygiene standards.
Methods Six representative metro stations were selected. Each subway station was monitored on 4 points at the platform and concourse respectively. The monitoring was conducted three times(morning, noon and evening)a day for 3 continuous days. The monitoring indices included air temperature, relative humidity, wind velocity, noise, respirable particulate matter(PM10), carbon monoxide(CO), carbon dioxide(CO2), formaldehyde, volatile organic compounds(VOC), the total colony forming units of bacteria and fungi.
Results Average wind velocity(0.42& #177;0.24)m/s, the concentration of CO2 (0.058& #177;0.015)% at the platform was slightly higher than those at the concourse(0.30& #177;0.13)m/s,(0.055& #177;0.011)%, and significant difference was found between the two, P<0.05. The relative humidity, total number of bacteria and fungi in the morning were higher than those at noon and evening respectively, and significant difference was found between these three groups(P<0.05). The concentration of PM10 was significantly lower at noon than those in the morning and evening. The concentration of formaldehyde decreased gradually along with the time, as well as the concentration of VOC. There were negative correlation between the volume of air flow per capita and total number of colony forming units of bacteria, CO2, PM10 respectively.
Conclusion The indoor air quality in the subway stations were impacted by fresh air supplement, passenger flow and the service life of the station. Microbial pollution, the concentration of CO2 and PM10 should be stressed as more important indices for assessing the air quality.
DownLoad: