A GIS-based modeling of environmental health risks in populated areas of Port-au-prince, Haiti
par Myrtho Joseph
University of Arizona - Master in Natural Resources Information System 1987
Public formal and informal markets are another potential source of waste and neighborhood pollution. Recent evidence has suggested a close relationship between the activities of the informal sector and the degradation observed in the urban environment of Port-au-Prince (Howard 1998). The so-called public markets contain unspeakable deleterious hygienic conditions harmful either for the attendants or people living in their proximity. The informal market places pack the downtown area of Port-au-Prince in a chaotic manner and at a point that is impossible to delineate its extent. According to Wargny (2004), everybody attempts to sell something. In the past, Port-au-Prince had some market places. Nowadays, port-au-prince is a market place, continuous, insisting, unstoppable, and obsessing.
Market features were digitized both as polygons and points. Yet the list provided by the communal administration's office was not exhaustive. Many spontaneous and dispersed markets are established along the streets and generate tons of waste for which no recovery plans exist. Some of them are the extended version of a traditional market whose capacity has exploded with the astounding population increase. The nature of these commercial exchange sites make it difficult if not impossible to delineate their physical extent and thus to integrate them in a model.
After calculating the Euclidean distance from markets provided in the SMRCS' list, point and polygon features were combined using the maximum function within the single output map algebra tool, and were reclassified as shown in Table 3 below:
Though there is not much theoretical support and previous studies available for validation, another factor affecting neighborhood pollution in Port-au-Prince is the major hospitals and the central cemetery. Not integrating them into the model would result in ignoring an important part of the specific environmental context in the study area. The conditions of sanitation within and around the hospitals, and more particularly the Sanitarium and the State University Hospital, make them hazardous and unsafe places to be exposed for long time. This situation is aggravated first, by the adjacent location of the mortuary to the general hospital often affected by the common lack of power to adequately maintain the equipment; second, the general belief and its concomitant negative impact that, since the type of service is public, its management will be inefficient. Consequently the level of care allocated is marked with negligence and falls far below the normal level it would be in a private structure.
EPA (2005) provides a list of air pollutants that may derive from hospitals even in normal operating situations. This list comprises mercury, found for instance in thermometers. Mercury emits toxic vapors that go to the lungs, and impact the kidneys, liver, respiratory system, and central nervous system. It can escape into the outdoor through any openings, and even its incineration doesn't prevent it from reaching the outdoor air. Polyvinyl chloride, used in plastic products, is another source of air pollution even when it is incinerated. It emits dioxin, which is a strong carcinogen that hampers normal reproduction and development even in small amounts.
However, the environment in question in this study area is still more complex than the normal conditions described by EPA, though quantitative information is lacking. The sanitation conditions in the main cemetery are precarious. Thus far the cemetery suffers from overpopulation. Often dead bodies are exposed to the air for hours to allow new corpses to be buried in the same grave or in the same hole. Moreover, cases of vandalism and stealing of fresh coffins are reported, which also expose corpses to the air and contributes to pollution.
For the cemetery the same distance approach was used to generate thresholds separated by 100 meters from 0 to 400 meters. Regarding the hospitals, first buffers from 10 to 100 meters were built in relation to the comparative sanitation conditions at these facilities. Then the result of the Euclidean distance on these buffered areas was reclassified into very high risk (4), high risk (3), moderate risk (2), and low risk (1) using corresponding distance thresholds of 50, 100, 200 and 300 meters.
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