A note on average vertical profiles of vehicular pollutant concentrations in urban street canyons

Dispersion of Volatile Hydrocarbons in Urban Street Canyons

“…Because VHCs are emitted by automobiles, VHCs, CO, and traffic load tend to have a similar pattern variation during the day. 15,23 VHC concentrations were correlated significantly with CO and NO values at 8 m. The CO and NO x automatic analyzers were situated at this level. The street level and rooftop values of VHCs, although giving similar patterns with CO and NO values, were not significantly correlated considering the different diffusion rates and chemical reactivity of those compounds.…”

“…The street level and rooftop values of VHCs, although giving similar patterns with CO and NO values, were not significantly correlated considering the different diffusion rates and chemical reactivity of those compounds. 15 It is interesting that the VHC rooftop concentrations were slightly correlated with the NO/NO 2 ratio (r 2 ϭ 0.79, n ϭ 16) and with O 3 (r 2 ϭ 0.67, n ϭ 16). Photochemical activity inside the canyons could be supposed for the reactive HCs.…”

“…Results for CO, NO x , and aerosol particles have shown an average vertical difference between 2 and 4. 12,13,15 Zoumakis reported that the CO vertical difference for Patission Street was approximately from 3 to 4. The values from this study are higher than those from the studies mentioned earlier and differ significantly with those reported in Paris for benzene.…”

“…Climatic conditions and dispersion of pollutants in canyons of this type are special, but very few studies are available on this subject. 20 In Athens, Zoumakis 15 has investigated the vertical gradient for CO. He reported that the difference in concentrations between ground level and a 29-m rooftop was approximately from 3 to 4.…”

“…5 Extensive research has been launched in recent years to study the wind flow and pollutant dispersion characteristics in street canopy. 6 These studies are referred to concentration gradients of pollutants in street canyons via measurements, [7][8][9][10][11][12][13][14][15] micrometeorology of street canyons, 16 -20 and development of mathematical models describing the pollutant's profile, taking into consideration other parameters that affect the concentration levels. 21,22 Studies conducted on the dispersion of vehicular emissions in street canyons have shown that variation in concentration at a given height depends on several factors, including vehicle-generated turbulence, variation in traffic flow, meteorological parameters, and geometry of the street, such as the street orientation and aspect ratio.…”