Dispersion of fine and coarse particulates in the near-field of vehicles ha
s not received as much attention as gaseous pollutants emitted from motor v
ehicles. Recent studies have pointed to evidence that fine particles in the
air could be significant contributors to respiratory and cardiovascular di
seases and mortality. This has increased our need to know more about the wa
y particulates disperse in the near-field, especially in street canyons, wh
ere pollutants tend to build up to high levels. Movement of vehicles is kno
wn to re-suspend particulates deposited on road surfaces resulting in incre
ased pollution levels. This paper presents the results of a study on disper
sion of particulate pollution from motor vehicles in urban areas. Levels of
airborne fine and coarse particulate matter were measured using two aeroso
l spectrometers in an urban street canyon in Nottingham, UK. Detailed infor
mation on traffic flow and vehicle classification was collected using video
recording and sample surveys. The monitoring survey was conducted for one
24-h period in January 1998. There was no direct correlation between fine p
articulates and traffic volume for 15-min averages. However, there was good
correlation between coarse particulates and traffic volume. This prompted
a study on the micro-level, at very short time scale, of the effect of vehi
cle movements on dispersion of particulate pollution in the near-field. Aut
ocorrelation analysis proved that, although there was strong periodicity in
traffic flow data, there was none in the levels of coarse and fine particl
es, suggesting that these levels do not follow the traffic flow pattern. Th
is was confirmed by cross-correlation analysis, which showed no systematic
relationship between particulates and traffic volume at different lags. (C)
1999 Elsevier Science B.V. All rights reserved.