Assessing health impacts of climate change

Improving the epidemiological and mechanistic science base and developing predictive methods for assessing the future health risks of human-induced climate change and increased exposure to UV radiation. Clarifying the range of health impacts caused by change in climate and increased exposure to ambient UV radiation. Developing early warning of any emerging health problems associated with climate change and ambient UV radiation.

Assessing and monitoring the impacts of climate change and stratospheric ozone depletion on health is important for a number of reasons. These include the provision of epidemiological data to inform policy-makers about the magnitude of effects. As a part of surveillance systems, such data can help to determine the requirements for and the effectiveness of preventive actions.

Improving data availability is a critical determinant of the ability to estimate and compare the disease burden caused by environmental factors and of the reliability of any assessment made. Although monitoring and assessment cannot replace action and policies aimed directly at improving environmental health conditions, they should be an intrinsic part of such programmes, focusing action on the priority issues and evaluating the effectiveness of the programmes carried out.

Industrial and other human activities have a significant impact on Earth's biophysical systems. Two of the best-known impacts are stratospheric ozone depletion. and the accumulation of greenhouse gases (notably CO2) in the lower atmosphere. Owing to the global scale and the long time frame of these changes, the potential health risks are diverse and often complex. Stratospheric ozone depletion will cause ultraviolet (UV) radiation-induced disorders, including skin cancers, cataracts and possibly immune suppression. Global warming (along with a likely increase in climate variability) will increase the frequency of severe weather events such as heat waves and floods, leading to injuries, altered rates of heat- and cold-related illnesses and deaths. The indirect health impact of climatic change is potentially more wide-reaching.

It is anticipated that climate change and stratospheric ozone depletion will have a range of health impacts. Some will result from direct effects (e.g. heatwave-related deaths and skin cancer induced by ultraviolet radiation); others will result from disturbances to complex physical and ecological processes (e.g. changes in patterns of infectious disease, drinking-water supplies and agricultural yields). Some health effects may become evident within the coming decade; others would take longer. Furthermore, failure to reduce fossil fuel combustion (as the principal means of reducing greenhouse gas emissions) will result directly in a continuing (and increasing) avoidable burden of mortality and disease from exposure to local air pollution.

Climate change will have indirect health impacts. Greater frequency and severity of heat waves, and changes in agriculture and food production, could affect nutritional status and vector distributions. The expansion of warmer areas may increase and extend the ranges of mosquito and other vector populations, affecting the incidence of vector-borne diseases and re-introducing malaria to Europe.

A number of infectious diseases are likely to be affected by climate change. These include vector-borne diseases (such as malaria, tick-borne encephalitis, Lyme disease, leishmaniasis and dengue) and other infectious diseases (such as legionellosis, salmonellosis, cholera, leptospirosis, cryptosporidiosis, campylobacter disease). Monitoring networks exist for some of these diseases in Europe: Salmonella infections are monitored through the Enter-net network and Legionella infections by the European Working Group on Legionella Infection (EWGLI). WHO/EURO is monitoring the occurrence in Europe of other infectious diseases. However, more coordinated and intense monitoring efforts are needed for cryptosporidiosis, campylobacter disease, tick-borne encephalitis and Lyme disease.

The 1992 United Nations Conference on Environment and Development (UNCED) recognized, in Agenda 21, that the unavoidable uncertainties attached to forecasting the potentially serious impacts of global environmental change do not justify a wait-and-see approach. Rather, in such circumstances there is a strong case for prudent and precautionary action. This "precautionary principle" is manifestly relevant to global climate change and stratospheric ozone depletion, because of the possible occurrence of irreversible changes in the world's environment and climate systems and because of the potentially serious nature of the associated health outcomes.

In light of climate change a World Health Organization (WHO) working group has recommended developing capacity to undertake national health impact assessments, with the aim of identifying the vulnerability of populations and subgroups, and ensure the necessary transfer of know-how among countries. These assessments will be made available for possible consideration in the forthcoming Third Assessment Report of the Intergovernmental Panel on Climate Change.

It would be valuable to include national health impact assessments for countries in the forthcoming Third Assessment Report of the IPCC, to be completed in the year 2000. This report is expected to become the primary source of information on regional and sectoral impacts of climate change for policy-makers, the scientific community and stakeholders in the early years of the next century.

At global level, a few initiatives have been taken to address the health impacts of climate change. In 1996, the World Health Organization (WHO), the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) tentatively established a collaborative network on climate and human health, which was endorsed in 1997 by the Inter-Agency Committee on the Climate Agenda (IACCA), a joint programme of international agencies concerned with climate issues. In May 1998, the World Health Assembly approved these initiatives and requested the Director-General to formalize the agreements and begin collaborative actions in support of Member States (resolution WHA 51.29). Other international bodies, including the World Bank, the International Council of for Science and IPCC, are also developing a range of health-related interests and activities.

Recommendation D from the World Health Organization preparing for the London WHO Health and Environment Conference (June 1999) supports developing capacities to undertake national health impact assessments with the aim of identifying the vulnerability of populations and subgroups, and ensure the necessary transfer of know-how among countries. These assessments will be made available for possible consideration in the forthcoming Third Assessment Report of the Intergovernmental Panel on Climate Change (2000).

Recommendations from the European Science Foundation, the World Health Organization and the European Commission, prepared for the London WHO Health and Environment Conference (June 1999) affirm the need for: (a) epidemiological studies of ongoing climatic variations and trends in relation to health; (b) development of mathematical models to forecast likely health outcomes in relation to the projected climatic/environmental changes; and (c) development of monitoring methods and systems to detect early evidence of health-related changes and to further inform the epidemiological and predictive modelling studies.

In line with the recommendations of the Helsinki Declaration, the European Science Foundation (ESF) launched a programme of scientific consultation. The programme was developed in close liaison with WHO-EURO and EC. Over 150 scientists from some 20 European countries and a wide range of disciplines, from neurobiology and toxicology to epidemiology and the social sciences, worked together in a series of workshops and field studies on pinpointing areas where further research is required to support the Declaration's goals. At a multidisciplinary ESF update meeting in June 1998, 45 leading scientists examined more than 80 detailed recommendations for further research and drew up a shortlist of 24 priority research issues. These science-driven recommendations were subsequently discussed at a joint EC/ESF/WHO-EURO "consensus conference", attended by policy-makers, scientists, and representatives of nongovernmental organizations and industry in October 1998. That conference emphasized the need to understand more fully the relative risks and impacts of environmental hazards. Without this knowledge, there is a danger that legislation could misdirect resources towards problems that have little real effect on health.

The consensus conference highlighted a number of strategic and specific research needs, with emphasis on those areas where there was an opportunity to be pro-active. Three sets of priorities for future research were identified: (a) (Overarching needs) Environment and health indicators, Health and environment geographical information systems; (b) (Cross-cutting issues) Risk assessment, The environmental contribution to social variations in health, Cognitive functions as mediators of environmental effects on health; (c) (Specific research areas) Air quality, Water quality and drinking-water, Environmental effects on cognitive functions, Children and unintentional injuries, Climate change and stratospheric ozone depletion.

 In light of climate change a World Health Organization (WHO) working group has recommended support be given to the identification, development, standardization, evaluation and broad use of systems for monitoring and assessing changes in environmental indicators, bio-indicators of health risk and impacts on health, and indicators of population health status across Europe. These systems must be coordinated with global monitoring activities.

In most cases of impact assessment, economic analysis cannot provide final answers, partly because of problems associated with evaluating some health impacts (such as changes in life expectancy), and partly because of inadequate understanding of the impact of environmental degradation on health, as well as the impact on the environment of economic policies. Many environment-related health issues are fraught with uncertainties.