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Roadside
toxic air monitoring is needed to reflect the actual
toxic air pollutant levels people are exposed to in
the outdoor environment in urban areas.
A
baseline study such as this study is recommended for
long-term trends analysis. However, follow up studies
conducted in the same format should be implemented every
5-10 years to review the urban air toxics situation.
If
a permanent or regular roadside toxic air pollutants
monitoring programme were to be set up in the future,
it is recommended that a representative compound for
each species should be chosen instead of monitoring
a great variety of toxic pollutant species, which would
be very costly and labour intensive. The representative
species should exist in relatively high concentrations
and also have high correlation with other TAP compounds.
Thus, the following are recommended indicator compounds
for each species:
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