Elements of example bus commute exposure to UFP Suburban indoors = 6 000 cm-3 Central indoors = 4 000 cm-3 Suburban outdoors = 11 000 cm-3 Central outdoors = 20–40 000 cm-3 On-bus = 50–100 000 cm-3 peaks = up to 400 000 cm-3 BUS concentrations 10 – 20 times INDOORS PEAK concentrations up to 100 times INDOORS Our AIM is to understand what controls EACH of these segments
CityFlux NERC 2004-7 investigating the transport and chemical transformation of pollutants (gases and aerosols) in urban areas, through measurements at three spatial scales: Individual plumes Street canyons Emission from an urban area
Oxford Road, Manchester (2006) 3 800 scheduled bus movements per day Every 14 seconds in daytime (Mon-Fri)
CO concentrations at Oxford Road northbound bus stops (Mon-Fri 7am – midnight)
CO and particles at Oxford Road Are particles formed or transformed within the canyon space? Above: TOF-AMS Below: DMPS, PTR- MS and CO
CityFlux: emission from the city centre (2005,6) Regular emission cycles Sheltering, recirculation, deposition, thermal stability & inversions Total particle number Particles 50 nm < D p < 32 m in 100+ size bins CO 2, H 2 O AMS fluxes (with CEH Edinburgh) VOC (PTR-MS, Univ. Lancaster ) Flux
Urban canopy particle turbulent ventilation fluxes All data from NERC CityFlux project, Manchester Above: fluxes Below: concentrations
Questions we will address in analysis Do urban street canyons act as reaction chambers? How does the amount and composition of the particles we breathe depend upon meteorology? At what rates are particles emitted by urban processes and formed in the urban atmosphere? What do Manchester (and other cities) add to the regional and global atmosphere?