London School of Hygiene & Tropical Medicine

The number of annual preventable deaths caused by hot weather in England and Wales is projected to increase from the current figure of around 2,000 to around 7,000 by the middle of the century. Predicted population growth, and warmer summers with more intense, longer-lasting heatwaves, will contribute to this increase, according to new research published in the Journal of Epidemiology and Community Health.

Researchers also estimated that the number of cold-related deaths may decrease due to predicted milder winters, but at a less dramatic pace from the current figure of around 41,000 per year to around 40,000 in the 2050s.

The findings from researchers at the London School of Hygiene & Tropical Medicine and Public Health England highlight the importance for public health bodies and policy makers to protect the population from temperature-related health burdens.

Older people, especially those over 85 with chronic health conditions, are most at risk of heat- or cold-related deaths. The majority of temperature-related deaths are due to cardiovascular or respiratory causes among frail people who are chronically ill.

With the total UK population projected to increase from 60 million in mid-2000s to 89 million by mid-2080s, and the 85+ age group expected to expand from 2% of the total population in the mid-2000s to 9% by the mid-2080s, the study demonstrates how these demographic changes will amplify temperature-related deaths.The study notes that if these future changes are not factored in, there would be a slight decrease in the total number of deaths overall. However, the authors stress that this net benefit to health from climate change is unrealistic since it is clear that demographic changes will occur.

The study also shows that while the rate of heat-related deaths (per 100,000 people) will increase, the decline in the cold-related death rate is greater. However, the authors note it is important to separate the relative effects of heat and cold on future mortality in the UK, since different measures may apply to reduce heat or cold related deaths. The authors say this is key in helping to understand how to reduce preventable mortality.

Lead author Dr Shakoor Hajat, Senior Lecturer in Epidemiology and Medical Statistics at the London School of Hygiene & Tropical Medicine, said: "Temperature-related deaths in the UK are likely to change in the future. The rate and variability of the expected changes in temperature mean it is unlikely our population will adapt as quickly as needed.

"The growth and ageing of our population will exacerbate the number of temperature-related deaths. The findings suggest health protection of the elderly will be vital, and there is a greater need for recognition of changes in society that could heighten risk among the elderly, such as living alone."

Rising fuel costs may make it harder to adapt to extremes of temperature, while increased widespread reliance on active cooling systems could simply end up driving up energy consumption and worsening the impact of climate change, say the authors. They suggest better and more sustainable options might instead include shading, thermal insulation, choice of construction materials implemented at the design stage of urban developments.

Publication

• Shakoor Hajat, Sotiris Vardoulakis, Clare Heaviside, Bernd Eggen. Climate change effects on human health: projections of temperature-related mortality for the UK during the 2020s, 2050s and 2080s. Journal of Epidemiology and Community Health. DOI: 10.1136/jech-2013-202449