Continuous monitoring of carbon monoxide in a deep street canyon

The results of a 1-week continuous monitoring campaign of carbon monoxide in a deep street canyon in the city of Naples are reported. CO was selected as a passive pollutant emitted by vehicle exhausts. The geometry of the canyon is: width W=5.8m and height H=33m (aspect ratio AR=H/W  =5.7). The monitoring campaign was carried out from 14 to 20 June 2006. CO concentration level was measured at pedestrian level (h=2.5m) and roof top level (h=25m). In the same period traffic flow in the street canyon was manually measured and the CO emission rate from vehicle exhausts was evaluated using the COPERT procedure. Meteorological conditions (wind velocity and direction) are also reported and their effect on CO concentration level in the canyon is discussed. Due to its geometry the street canyon monitored may be considered almost ideal. The results show that the deep street canyon is a “hot spot” compared with roads with high traffic flows in the urban area of Naples, and that significant differences exist between concentration levels at pedestrian and roof top level. Some insights into the effect and relative importance of meteorological parameters on the air quality in the canyon are also given. The monitoring data collected have been made available on the web and can be used by other researchers to test air dispersion models.