PMC

Schematic of the mini air station (MAS) system with different components.

MAS field tests at the Central Air Quality Monitoring Station (AQMS), Hong Kong, China.

Comparison of the PM_2.5 concentration from MAS and AQMS. (a) Time series of concentration; (b) histogram of the concentration difference in the 1-min and 5-min time average.

Linearity test results in dry gas conditions of (a) the NO₂ sensor; (b) the CO sensor; (c) POM.

Comparison of the NO₂ concentration from MAS and AQMS. (a) Time series of concentration; (b) histogram of the concentration difference in the 1-min and 5-min time average.

Comparison of the CO concentration from MAS and AQMS. (a) Time series of concentration; (b) histogram of the concentration difference in the 1-min and 5-min time average.

The pollutants’ concentrations inside WHC from MAS and at the Central AQMS. (a) Time series for NO₂; (b) time series for O₃; (c) time series for CO; (d) time series for PM_2.5.

The pollutants’ concentrations before, during and after the Marathon at TST from MAS and at Mong Kok from AQMS. (a) Time series for NO₂; (b) time series for O₃; (c) time series for CO; (d) time series for PM_2.5.

The pollutants’ concentrations before, during and after the Marathon at SSP from MAS and at Sham Shui Po AQMS. CO is not reported by the Sham Shui Po AQMS site. (a) Time series for NO₂; (b) time series for O₃; (c) time series for CO; (d) time series for PM_2.5.

Air monitoring stations along: (a) the full/half marathon route; (b) the 10-km marathon route; the nearby AQMS run by HKEPD (c); Sham Shui Po AQMS near SSP; (d) Central AQMS near West Harbor Crossing (WHC); (e) Mong Kok AQMS near Tsim Sha Tsui (TST).