AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Variability of Aerosols and Chemical Composition of PM10, PM2.5 and PM1 in the Prague Underground Metro
MICHAEL CUSACK, Jakub Ondrecek, Nicholas Talbot, Jaroslav Schwarz, Vladimir Zdimal, Institute of Chemical Process Fundamentals of the ASCR, v. v
Abstract Number: 567 Working Group: Indoor Aerosols
Abstract One of the principal measures employed by developed countries to combat traffic congestion and emissions in urbanised areas is through the promotion of public transport. Of the various modes of public transport available in many urban areas, underground trains are considered one of the cleanest from an environmental perspective. However, the air quality in underground train networks has been shown to be especially poor, and not clearly understood. This work is a result of a 24 hour measurement campaign performed on a platform of the Prague metro. Real time measurements of PM concentrations, particle number concentrations and particle number size distribution were performed, of which the latter two were measured for the first time in the Prague metro. Furthermore, few publications exist on particle number size distribution for metro microenvironments. Gravimetric sampling of PM was also performed, providing vital information on the chemical composition of PM10, PM2.5 and PM1.
The variation of PM was found to be directly affected by the movement of incoming and outgoing trains into the tunnel, from turbulence and resuspension, with highest concentrations occurring during morning rush hour. Concentrations subsequently decreased when trains were less frequent. Particle number concentrations did not vary substantially during the day, increasing only gradually. Concentrations were at their highest when trains were less frequent. PM was found to be characterised mostly by Fe species (66% of PM10) as a result of wheel-rail mechanical abrasion. The next most abundant species were total carbon and secondary inorganic aerosols, most likely from surface air entrainment. Finally, certain trace elements such as Ba, CuO, MnO, ZnO, Cr2O3, Mo, Sb, Sn, Ni, Co, Li and Cd are all enriched during hours when trains are passing the platform, relative to out-of-operation hours, the probable sources being wheel-rail abrasion, sparking from electrical cables and brake pads.