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The health of humans is closely linked with their surrounding environment. All biological and microbiological activities and processes are sustained directly and/or indirectly through three media, i.e. soil, water and air. Changes in the characteristics of these media and the processes these media support on the land, in the water or in the atmosphere influence directly and/or indirectly human health. Traditionally the focus was on the risk associated with the exposure of humans to environmental toxins such as heavy metals, radiation and certain chemicals for example endocrine disruptors and heavy metals in food products, the air and water (Myers and Patz, 2009). The scale and seriousness of the impacts of these toxins are still a serious concern and research and monitoring are done on a continuous basis to improve the current knowledge and understanding of contamination-, exposure- and impact pathways of chemicals.
Currently the focus has shifted to large scale, human driven or so-called anthropogenic changes to the natural environment and the impacts of these changes on the health of humans. The major human-driven environmental changes can be classified as follows i) changes to the climate system as a result of the enhanced greenhouse effect caused by emissions of greenhouse gases from man-made processes and activities; ii) the detoriation of ecosystem services for example the decline or loss of the natural filtering and cleaning ability of wetlands or the loss of the ability of areas to trap water and reducing the risk or severity of floods; and iii) large-scale land-use change for example deforestation for food production and settlement purposes, or the conversion of grasslands to cropland or built-up areas. In the literature the following five emerging health impacts as a result of these changes are listed as among the top major public health concerns, namely i) an increase in infectious diseases; ii) water scarcity; iii) food scarcity; iv) acid precipitation; and v) population displacement (Myers and Patz, 2009). In general infectious diseases are considered the least important of the five mentioned emerging health threats due to the general ability of humans to develop an immune response in some instances and/or to intervene by means of for example vaccination programs or the eradication or suppression of the cause(s) of some of these diseases where possible.
It is often difficult to distinguish between natural occurring and human-induced changes or the relative contribution of each to the overall effect or impact of the change. Currently climate change receives a huge amount of attention and publicity. Although the relative contribution of humans to the phenomenon is still debated in scientific and political circles, the impacts of a changing climate are already experienced at different spatial and temporal scales and intensity levels (WHO 2003; IPCC AR4 WGI, 2007; IPCC AR4 WGII, 2007). Climate change is complex in terms of its spatial and temporal characteristics, the processes and factors driving the phenomenon and the impacts it has on different areas and communities over time. It is also not always possible to quantify these impacts on for example the health of people living in a certain area for a number of reasons. One major difficulty is the lack of long term health data for a specific area or areas that can be linked to changes in the climate system. The links between human health, the natural environment and systems operating at different time and spatial scales contribute to the complexity associated with distinguishing the health effects of climate change from other global environmental changes.
Documented direct health effects of climate change include extreme events such as floods, hot and cold spells which can lead to drowning, heat exhaustion, and freezing. Indirect health effects of climate change include for example food scarcity leading to famine as a result of droughts or floods when crops and/or livestock are lost. The spread and/or increase of the incidence of infectious and vectorborne diseases is linked to for example the failure of water treatment and sanitation facilities during flood events and/or favourable environmental conditions such as increased temperature and nutrient availability that contribute to the rapid growth and spread of viral and bacterial pathogens and the vectors of diseases such as malaria.
The vulnerability and capacity to adapt to global changes and therefore also climate change by a community or communities depends on a number of factors. These factors include the general health status, for example the prevalence of cardiovascular diseases, HIV and TB, malnutrition or stunting especially in young children; level of education and awareness; economic status; general demographic profile for example gender and age profiles; migration patterns and levels, level of infrastructure development and maintenance; access to and availability of skilled medical personnel and facilities, and population density.
The potentially most important climate change related health impacts on communities in the K2C study area include a) water scarcity (parts of the K2C area are already suffering from water shortages and as rainfall becomes more erratic in the future the current situation will be exacerbated); b) food scarcity as a result of higher temperatures and unpredictable rainfall (although economic factors contribute largely to the ability of groups and individuals to afford food stuff, a decline in food production as a result of an increase in pests due to higher temperatures and plant heat stress will reduce the food production capacity of the area). This will have a negative impact on communities who are dependent on locally produced food and who are already suffering from poor nutrition and malnutrition (Saloojee et al., 2007); c) population displacement; and to some extent d) the impact of heat stress on individuals in communities suffering from an increasing prevalence of cardiovascular diseases.
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