A real-time monitoring campaign was conducted from November 11th to November 15th, 2013 in a Shanghai subway tunnel, consisting of temperature (T), relative humidity (RH) and PM!, PM_(2.5) and PM_(10). The objective was to characterize PM and microclimate in the subway tunnel. Results indicated that median values of T, RH, PM|, PM_(2.5)and PM_(10)were 29.4°C, 29.6%, 42 μg/m~3, 46 μg/m~3 and 58 μg/m~3, respectively. Air quality in the tunnel was comparatively good, with 76% of PM_(2.5) and 91% of PM_(10) reaching relative standards. Independent samples t-test verified that PM1, PM_(2.5) and PM_(10) presented significant statistical differences between peak hours and off-peak hours (p<0.05). Notable weekly variation emerged during monitoring periods, which of all particles was as following: Friday > Thursday > Monday, Tuesday > Wednesday. Ratios of PM1/PM_(10) and PM_(2.5)/PM_(10) were 0.49-1.00 and 0.56-1.00, respectively, which were high in outage and low in operation of trains. This phenomenon might result from plenty of coarse particles generated by mechanical grinding in the process of train driving.
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