Heat related deaths could rise from 2000 to 12 000 a year by the 2080s, health agency says

BMJ 2012; 345 doi: (Published 11 September 2012) Cite this as: BMJ 2012;345:e6138
  1. Ingrid Torjesen
  1. 1London

More deaths of elderly people relating to hot weather, a longer hay fever season, and more people with asthma are just some of the public health implications of climate change predicted for the United Kingdom by a detailed report published today by the Health Protection Agency.1

There will also be more flooding, more ultraviolet light, and a greater potential for exotic, disease carrying mosquitoes to invade the UK, says the HPA’s report, unveiled at its annual conference in Warwick.

Temperatures in the UK have been rising by around 0.25°C a decade since the 1960s, while the amount of summer rainfall has decreased and that of winter rainfall has increased. It is predicted that the mean average temperature will rise by another 2°C to 5°C by 2080 and that heat waves will become more frequent. Southern-central and eastern England are expected to see the largest temperatures rises, with rises being most pronounced in urban areas.

Currently around 2000 people die prematurely in the UK a year because of heat. Cold related deaths are far more common, but the ratio of heat to cold related deaths is likely to fall as heat related mortality increases steeply and cold related deaths decline. Heat related mortality is predicted to rise by 70% by the 2020s and by around 540% by the 2080s, increasing the number of heat related deaths to 12 000 a year, the HPA says, with elderly people most at risk.

As the temperature rises, the hay fever season is expected to lengthen and to be more intense. The distribution of plants in the UK will change, with an expected invasion of more plants, such as American ragweed, which produces highly allergenic pollen and has already colonised parts of Europe. Pollen is also expected to become more potent: there will be more, smaller fractions of pollen.

Roy Kennedy, professor of aerobiology and microbial science at the University of Worcester, told an HPA press conference: “The more allergen that occurs in smaller fractions, the more likely people are to ingest it or breathe it in. One potential impact that climate change might have is that pollen might burst, itself leading to higher amounts of that smaller fraction.”

He said that the longer pollen season, a different distribution of pollen, a wider range of allergens, and increased pollen potency might lead to a larger proportion of the population becoming sensitised to pollen. The health effects could be “more than just irritation” of hay fever, because the allergens could also trigger asthma in adults. “There is a relationship between sensitisation for one allergen and the possibility of developing asthma at some later stage,” he said.

The HPA’s report predicts that a 5°C temperature rise will increase concentrations of ground level ozone and lead to a 4% rise in ozone related deaths (an extra 500 deaths a year). Sotiris Vardoulakis, of the HPA’s Centre for Radiation, Chemical and Environmental Hazards air pollution unit, said that ozone was also a powerful respiratory irritant that could cause sensitisation to other allergens and exacerbate asthma symptoms.

Climate change will also affect the indoor environment in terms of buildings overheating, increased indoor biological and chemical contamination, and potential damage from increased flooding, the report adds.

Jill Meara, deputy director of the Centre for Radiation, Chemical and Environmental Hazards, said that river and coastal flooding was expected to become more common, even though overall rainfall was not expected to increase. “The projections are that there will be more rain in winter and less in the summer months, and changes in the intensity of the rain—a lumpy distribution with more potential for floods,” she said.

“The government has a hot weather plan and a cold weather plan, and we are recommending that we have a specific UK-wide set of flood plans to make sure we know how to respond.” This would cover where houses, hospitals, and other health facilities are built, crisis management plans for the NHS in case of flooding, and the potential effects of flooding on health.

Andy Haines, the HPA’s climate change chief, said, “We need very substantial reductions in greenhouse gas emissions, certainly on the part of an industrialised country like the UK, if we are to avert dangerous climate change.”

Many of the actions needed to avert climate change were seen as “difficult and expensive,” he admitted, so the report also looked at some of the additional benefits that may accrue from their introduction.

He said, “As you reduce coal combustion, not only do you decrease greenhouse gas emissions, you also reduce fine particulate air pollution, which as we know is a major killer in many parts of the world.” Increasing active travel such as walking and cycling can prevent many chronic diseases related to a sedentary lifestyle, such as heart disease, stroke, diabetes, cancer, dementia, and depression, he added.

“That has the potential to offset at least some of the costs of these policies by reducing cost to the NHS,” Haines said.


Cite this as: BMJ 2012;345:e6138