Abstract:
Objective To collect data of major air pollutants in Shanghai subway carriages in four discrete months and to provide scientific basis and reasonable proposals for disease prevention and health supervision.
Methods Carriages of DC01, AC01 and C serving Shanghai metro line 1, 3 and 8 were selected and monitored 3 times per day for 3 continuous days in May, July, November of 2009 and January of 2010. The monitoring indices included total colony forming units (CFU) of bacteria and fungi, carbon monoxide (CO), carbon dioxide (CO2), volatile organic compound (VOC) and respirable particulate matter (PM10).
Results There was no significant difference in microbiological pollution index among all selected carriages, and the average annual level was lower than the reference standard limit. The concentration of CO in line 3's carriages was significantly lower than that in other lines'. The average concentration of CO2 in carriages of line 1 and line 3 was higher than that of line 8. The concentrations of VOC and PM10 in line 1's carriages were significantly higher than those in other lines'. The total counts of bacteria exceeded the related standard in May and July, and were as high as 87.6 colonies per plate in July. The concentrations of CO2 exceeded the related standard in the three lines' carriages in all 4 months and the highest was 0.37%. The total CFU of bacteria and fungi and the concentrations of CO2 and PM10 were significantly lower at noon than in the morning and in the afternoon, presenting a typical trough shape. The concentration of VOC was significantly lower in the afternoon than in the morning. The average total count of fungi and the concentration of VOC in July were significantly higher than in the other monitored months (P < 0.05). The concentration of PM10 was significantly higher in January than in other monitored months, with the maximum of 0.278 mg/m3.
Conclusion The total count of bacteria in Shanghai subway carriages exceeded the related standard. The concentrations of CO2 significantly exceeded the related standard in all 4 months.
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