air pollution affects health is a fact that almost goes without
the other hand, the effect of
emissions from vehicles, factories and power plants varies for
different districts, and we
know very little about the precise relationship between the
emissions and public health apart from generalities, e.g. that air
quality in Tung Chung, Tuen Mun and West Kowloon is more
directly affected by PRD emission; the central business district
suffers mostly from local traffic emissions; while fine
particulates (PM2.5) is probably a problem common to all.
The public health authorities should pay greater
attention to researching and dissemination information about the impact
of pollution on health.
Environmental Protection Department conducted a sophisticated
modeling study in 1999, upon which the current emission targets
are derived. However,
more information would be needed to correlate the relationship
between air pollution and health, and to track the causes and
effects of pollution in different districts.
Instead of sporadic and ad hoc studies, government should
conduct regular and systematic research on the effect of
pollution in different districts, to enable the cost, benefits
and effectiveness of various abatement measures to be assessed.
The starting point is to establish a database identifying
main pollution sources. In
, the Air Pollution Control Ordinance already requires all
licensees to submit emission reports.
For non-licensed sources such as roadside emissions, the
data will have to be estimated by the EPD and Transport
Department. The same
should then be done for the Mainland.
The EPD¡¦s 2002 study (using 1997 as the base year)
already provided a framework with the now well-known emission
reduction objectives for the four major pollutants.
Now that the
has launched a comprehensive study to identify the main sources
of pollution in the PRD, refinements could be incorporated over
time to yield higher-quality data and to mirror changing
other words, a complete database of pollution sources can now be
technically compiled, say after five years of data collection.
comprehensive database will enable a geographical contour of
emissions to be drawn up, which will be a useful information
tool for the public. Such
pollution mapping will shed light on the correlation between
emission source and pollution concentration, thus providing a
basis for setting more specific emission reduction targets over
time. How and to
what extent power plants or mobile sources affect the air
quality in specific areas like
or Mongkok can be studied more thoroughly, with a view to
improving the micro-climates of these districts through the
appropriate town planning and urban design measures.
The correlation between public health and district
pollution will thus help address the risk to public health more
In addition, it is important also to better understand acute
exposure to pollution in Hong Kong¡¦s heavily trafficked and
poorly ventilated street canyons ¡V for example, how many
people are pedestrians or are in the vehicles each day and for
how long on average are they exposed? How many vendors and shop
workers spend their entire working day in such conditions? What
is the air quality indoors for offices/residences along such
routes and how many people are thereby routinely exposed to
acute levels of roadside air pollution? With such information it
should be possible to also survey the respiratory health of a
sample of people from the above groups so that we can begin to
get a better picture of the consequences of frequent acute
pollution exposure episodes.