Maps and spatial information technologies (Geographical Information Systems) in health and environment decision-making


The advantages of displaying information in a spatial format are largely related to the visual impact and thus effective communication of the issues. Maps can be extremely powerful communication tools – especially if they are colourful or creative – showing linkages between two or more variables, indicating areas of concern, showing the extent of a problem, and comparing information from different time periods. They can deliver a message without pages of text, and are therefore ideal for busy people or those who want a strategic view of the situation. Although maps are commonplace in many areas of the world and in many disciplines, it must be remembered that they are not easily understood by everyone, and thus need to be carefully constructed to convey the intended message.

Obviously, geo-referenced information gives a spatial dimension to environment–health linkages – not only pinpointing issues but also describing the intensity or extent of the cause or effect. Maps can highlight localized issues (for example, exposure to disease from location of disposal sites) as well as more diffuse issues (for example, exposure to radiation from reductions in atmospheric ozone). Both types of information are useful in planning (ex ante) (see Figure 2) and assessment (ex post) of health impacts.

Fig. 2 - Use of maps in planning
Fig. 2 - Use of maps in planning

This map depicts an overlay of poverty mapping data with information concerning an outbreak of cholera in the KwaZulu Natal province of South Africa in early 2001. It shows that the disease outbreak originated in areas of very high and high poverty and spread through and towards other poor areas. The map was produced through the cooperation of several government agencies, including Statistics-SA (developer of the national poverty map), the Department of Health (provided disease data), and the Department of Water Affairs (provided information on safe water supplies). It served as the basis for a disease control strategy and helped to target health education messages in affected and high-risk communities. Using this map, the outbreak was effectively contained within three months, with a resulting fatality rate of (0.22%) among the lowest ever observed.

From: Henninger N., & Snel, M., 2002. Where are the poor? Experiences with the development and use of poverty maps. WRI and UNEP/GRID-Arendal.

Maps of environmental information can be used as early-warning tools (see Figure 3) for health planners. For example, mapping environmental criteria in the determination of malaria prevalence may give insights into areas where malaria may be occurring but is currently not well reported, as well as into possible changes in the distribution of the disease under altered climate regimes.

The mapping malaria risk in Africa project (MARA/ARMA) has defined the climatic conditions necessary for malaria transmission, and used geographical information systems (GIS) to link this relationship to maps of key climate variables covering the entire African continent. The resulting map of 'climate suitability' for transmission has been demonstrated to give an accurate picture of the true distribution of malaria (1,2). The maps have been used to provide better estimates of the true number of people suffering from malaria, and to help direct disease control. Other studies have used this model to investigate the potential effect of climate change in the future. These indicate that climate change may not necessarily increase the overall area suitable for malaria, but could cause the disease to shift to some new areas (3), and increase the total amount of time for which people are exposed to transmission (2).

Other examples include:

  • mapping land degradation, together with long-term rainfall variability, to indicate potential future food production changes;
  • mapping forest fires as an indication of air pollution; and
  • mapping flood-prone areas as early determination of potential cholera outbreaks.
Fig. 4 - Use of maps to detect changes over time
Fig. 4 - Use of maps to detect changes over time

Some maps can be used to indicate trends over time (see Figure 4), if the same variables are mapped in the same way and at the same scales at regular intervals. Land cover or land use change is often mapped over time intervals, and can be used to track changes in environmental health issues (for example, the rate of urban expansion, agricultural expansion, or infrastructure development). Some data sets can be recorded and displayed in near-real time, such as air pollution dispersion. This enables planners to issue warnings or to take mitigatory actions (such as UV warnings for holidaymakers).

From 1970 to 1990, there was significant deforestation of both primary and secondary forests in Thailand: during this thirty-year period, the area covered by primary and secondary forest declined by more than half. Many other regions of the world are affected by deforestation: namely in South America (Brazil), Central Africa (Congo), South-East Asia (Indonesia) and Eastern Europe. Source: World Atlas of Desertification, United Nations Environment Programme (UNEP), International Soil Reference and Information Centre (ISRIC) (1997).