Background
There have been many multicity studies assessing health effects of the
population’s exposure to PM10. They assume that there is homogeneous exposure to PM10
and the monitoring locations are representative of the population’s exposure. In a
densely urban environment, like Hong Kong, street canyons are common and could alter
PM10 exposure. The horizontal and vertical dispersion of PM10 in the urban environment
is complex due to the interactions of street geometric, metrological and pollution source
conditions. The airGIS/OSPM is a box and plume mathematical model which was
designed to model this complex dispersion of PM10.
Objectives
This study aims to utilize the airGIS/OSPM to assess how the health impact is
affected by the misclassifications of within city air pollution exposure. This helps
assessing the feasibility of using the airGIS/OSPM in health studies.
Methods
The airGIS/OSPM was used for an urban area of Hong Kong, in the north west of
Kowloon Peninsular for a period from 1998 to spring 2011. PM10 concentration’s were
estimated at field measurement points, an EPD roadside monitoring site, and subjects in a
subset of the elderly healthcare center cohort and for all building addresses in the
modeled area.
The airGIS/OSPM was validated by conducting a PM10 measurement campaign
over the winter of 2010 to 2011. Also validation was conducted using the measurements
of the Mong Kok EPD roadside monitoring station.
A pilot study using the time stratified case-crossover analysis was conducted to
explore the effects of using the airGIS/OSPM to express the subjects’ short-term outdoor
residential exposure to PM10 on all cause mortality.
AirGIS/OSPM PM10 estimates were compared with ambient concentrations
obtained from the EPD monitoring network. The population mean exposure was
calculated using the airGIS/OSPM estimated PM10 concentration at all building address
points from 2007 to 2009 at the ground level and at middle building height level.
The airGIS/OSPM estimate was used to identify spatial variation of PM10 within
the study area.
Results
The airGIS/OSPM estimated well the measured PM10 concentration from the field
measurement campaign and the EPD Mong Kok station.
The airGIS/OSPM estimate and the ambient measure for EHC subject exposure
both found an odds ratio for all cause mortality there was no difference from unity
between case and control times.
The airGIS/OSPM derived mean PM10 concentration at the middle height of each
building was 54.8μg/m3 while that at the all EPD was 54.4μg/m3. At ground level the
airGIS/OSPM PM10 estimate was 58.35μg/m3 while that at the EPD was 54.41μg/m3.
Conclusion
The misclassification of PM10 was negligible at the middle of buildings, but for
people regularly working in ground level microenvironments are often exposed to PM10
concentrations that are higher than those measured at EPD monitors.
It is feasible to use the airGIS/OSPM model to estimate PM10 exposure. The
small spatial variation in exposure means the airGIS/OSPM may not be appropriate in
assessing the short-term PM10 exposure, but due to the larger effect size it might be
important in long-term exposure assessment. / published_or_final_version / Community Medicine / Master / Master of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/161544 |
| Date | January 2011 |
| Creators | Chapman, Peter Stuart. |
| Contributors | Wong, CM, Lam, TH, Lai, HK |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47869847 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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