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 Background
Nowadays in the world, disasters, either natural or man-made, happen almost
daily. They claim substantial amounts of
lives and leave many people injured and
homeless(1). Middle East countries also
suffer significantly from disasters(2).
For instance, earthquake and floods are
among the most important natural
disasters in some of the countries
within the region(3). Notably, in the
year 2004 the Bam earthquake in Iran
caused thousands of deaths, injuries and
homelessness(4). Therefore, the health
authorities within the region should be
ready for managing disasters as soon as
they occur. To do this, they need
precise information from the area
affected by the disaster. They must also
be able to link data collection and
analysis to make their managerial
decision as soon as possible(5).
Recently, the Global Positioning System
(GPS) provided this opportunity for the
health authorities to collect and
analyze accurate data once a disaster
occurs.
Global Positioning System (GPS)
GPS has been made fully available in 1995 by the U.S. Department of Defense (DoD).
It consists of a system of at least 24
and up to 32 solar-powered satellites,
five ground-based stations and
receivers. Each satellite (NAVSTAR) is
orbiting the Earth every 12 hours and
transmitting radio pulses at very
precisely timed intervals. Ground-based
stations are responsible for monitoring
the tracks and innards of the
satellites. The receivers consist of an
antenna, electronics, a microcomputer,
controls and a screen. With this
constellation, GPS permits the user on
the ground to know his/her position
information with a high accuracy(6). It
should be noted that a receiver needs
signals from at least four satellites to
determine a position in three dimensions
i.e. latitude (X), longitude (Y), and
elevation (Z)(7). Although the prime
application of GPS has been for military
purposes, it has now become a standard
method for spatial data capturing in
public health studies as well(8)
especially in developed countries(9).
The data captured using GPS can directly
enter into the Geographical Information
System (GIS) (10). GISs are defined as
software systems that can automatically
capture, store, retrieve, analyse and
display spatial data(11). Even though
the development of GIS technology dates
back to four decades ago(12), it is now
widely applied in public health problems
studies, especially in the epidemiology
of infectious diseases(13).
Nevertheless, one of the best advantages
of GPS is that different components of
its receiver can work efficiently in
extreme weather conditions such as
torrential rain, sandstorms and high
temperatures. This gives GPS a key role
to play in combination with GIS,
especially in studying different aspects
of a disaster during its early
stages(9). For instance, once a disaster
occurs, the authority should have
immediate and accurate information from
the field about the event and the number
of people who have been affected(14).
During the early stages of a disaster,
it is not possible to use the well known
systematic random sampling to determine
the number of affected people. However,
GPS can be applied to gather necessary
information for mapping the region. The
captured data could then be entered into
GIS and be mapped. As soon as the
mapping process is done, one would be
able to apply other feasible methods of
sampling such as quadrant to have
relatively precise information about the
size of the affected population. In this
method, some random squares are drawn
over the populated area e.g. the camp. A
random sub-sample of the households in
each randomly selected block is then
selected for the enumeration
purposes(9). Moreover, some GPS
receivers are very flexible so that the
user will be able to place its antenna
on top of a car, and to connect the
receiver to a portable computer which
could also be placed inside the car. As
a result, when the user drives along,
the path of his/her vehicle will be
continuously recorded and immediately
displayed on the screen(11).
Furthermore, using GPS and some extra
devices allows the user to read and
answer his/her questionnaire
electronically without using paper. It
can also be used to record and map
important landmarks such as health
clinics and water points,
simultaneously(9). Without any doubt,
these facilities could help public
health authorities accomplish their
surveys immediately after a disaster
occurs. Last but not least, one should
also be aware that GPS has its own
limitations(14). First, the
implementation of the GPS/GIS
combination needs a considerable
commitment of time, money, and
training(8). It has been estimated
that given the current rates it may
costs up to US$ 100,000 to buy
appropriate equipment and to pay one
full salary(9). Secondly, since radio
waves that NAVSTAR transmits have very
short length they do not penetrate
matter and as a result one would not be
able to measure his/her position while
he/she is inside building, underground,
amongst tall buildings and dense tree
cover(6).
Conclusion
The integrating use of GPS and GISs now provide an environment for the
public health authorities and
researchers to improve their
understanding from the place side of the
health problems. This should be
considered as an excellent opportunity
in the developing countries, including
countries within the Middle East region,
to manage more quickly and more
efficiently the disasters which often
happen within the region.
References
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