The health or the well-being of humans is closely associated with the ‘health’ of their surrounding environment. Changes to the environment as a result of natural processes and cycles, human processes and activities or a combination of both can affect human health directly and indirectly.
The major anthropogenic driven causes of changes to the environment include the enhanced greenhouse effect that affects the earth’s climate system, land-use changes and the deterioration of ecosystem services. Five emerging public health threats that are currently of major concern on a localised scale as a result of these human-driven global changes include i) increased exposure to infectious disease, ii) famine or food scarcity, iii) decreasing water quality and quantity for human consumption purposes, iv) increase and/or wider spread in natural disasters, and v) population displacement. The exposure and increased exposure of humans to chemicals used for example in pesticides and herbicides is also still a major concern. Confounding socio-economic and political factors such as gender inequality, poverty, level of education, migration, the lack of sufficient medical care and treatment facilities and political instability also contribute to the vulnerability,the level of vulnerability and the resilience of local communities and individuals to environmental changes.
Examples of direct human health effects include drowning, heat exhaustion and freezing as a result of extreme weather events such as floods, droughts, hot and cold spells. Indirect effects include the increase and/or spread of infectious diseases as a result of the failure of water and sanitation infrastructures during flood events or famine when crops fail and/or livestock are lost during drought and flood events. Another example of how an environmental change can affect human health is the appearance or increase of malaria cases in deforested areas. Deforestation has been linked to an increased risk of malaria transmission as a result of a) favourable environmental conditions that affect the life cycle and breeding behaviour of the malaria vector, i.e. mosquitoes, especially during the warm rainfall season when areas of standing water are created, and b) a higher incidence of mosquito night biting/landing rates in cleared areas inhabited by humans. Further, it is not always possible to determine or distinguish the relative contribution of a specific environmental change to a health effect as a combination of environmental changes and other factors are likely to contribute in varying degrees to the health effect experienced.
health, infectious disease, vector borne diseases, air quality, water quality, climate variability, climate change, global change, agriculture, land-use change, deforestation, extreme weather events,vulnerability, poverty