Maps and spatial information technologies (Geographical Information Systems) in health and environment decision-making
This policy brief relates to the use of spatial representation of environmental information, and how such techniques can support the integrated analysis of health and environment data, as well as presentation of summary information. This paper reviews the strengths and weaknesses of maps and mapping techniques, provides some key illustrations and case studies, and lists some of the major information sources.
Why use maps?
Maps and spatial information technologies have three main advantages:
- They can be a means of recording and storing information. Governments, the private sector, development agencies, and civil society groups store large quantities of information about the environment and the location of natural resources, as well as about populations and demographic trends.
- They can be used to identify and investigate spatial patterns. Maps draw attention to spatial relationships, for example the distribution of a resource over space, over time, or in relation to other factors such as the presence or growth of human settlements. Once these relationships are recognized, we can start to analyse them and search for the underlying causes and processes, which in turn can be useful in improving planning and development.
- They are effective in presenting information and communicating findings. Maps allow us to convey information and findings that are difficult to express verbally, or to condense messages that would be lengthier to describe in words. They are often more memorable, because they have colour and shape. They can be used to demonstrate relationships in a way that is more striking – by showing the intensity of a problem in one area relative to the intensity in another area, or by showing the change in distribution of a resource over time.
The most commonly mapped environmental information of relevance to the health sector includes:
- pollution sources and affected areas (including sewage, solid waste, hazardous waste, industrial pollution, smoke and other emissions, and radiation);
- land cover and use (including vegetation type, vegetation change and condition, agriculture, forestry, and soil type and condition);
- water availability and quality;
- energy sources and use (including fossil fuel use, electrical connectivity, biomass use, and renewable energy sources); and
- biological resources (including protected areas and recreational sites, endangered species, and medicinal resources).
Availability and sources of this information are given in detail below, under the directory of references.
Mapping techniques can be used in two main ways to show the links between environment and health. Simple overlays (comparisons) of environmental and socioeconomic (health) data can be used to identify patterns, which can then be investigated later for correlations, as in the example shown in Figure 1. Once the causal relationship is known, however, spatial models can also be developed to predict (in this case) changes in health based on environmental changes. An example would be mapping vulnerability to disease outbreaks based on water quality information, temperature, and rainfall.