Rs. Bailie et al., TRENDS IN PHOTOCHEMICAL SMOG IN THE CAPE PENINSULA AND THE IMPLICATIONS FOR HEALTH, South African medical journal, 84(11), 1994, pp. 738-742
There has been growing public concern over reports of increasing air p
ollution in the Cape Peninsula. Attention has been focused on the 'bro
wn haze' and on photochemical smog. Because of deficiencies in the mon
itoring equipment, information on trends in photochemical smog levels
over the past decade is limited. Trends in oxides of nitrogen, one of
the main precursors of photochemical smog, and therefore an indicator
of the potential for its formation, were examined for the period 1984
- 1993. Meaningful data for determining trends were available from onl
y a single site. Increases in mean monthly levels, peak hourly levels
and the number of times guidelines were exceeded were demonstrated. Gi
ven the dynamics of formation of photochemical smog and the particular
role of motor vehicles, it is argued that the trends measured at this
site are probably an underestimate of the trends in other parts of th
e Cape Town metropolitan area. Some of the precursors of photochemical
smog, notably nitrogen dioxide, and some of its components, notably o
zone, have been shown to be detrimental to respiratory health at level
s close to, or below, current recommended guidelines. A continuing inc
rease in these pollutants will therefore result in more respiratory il
lness, particularly among susceptible groups. This calls for an upgrad
ing of monitoring of air pollution in Cape Town and for appropriate st
eps to prevent its further increase.