Heat waves and health protection
Authors: R Sari Kovats
Journal: BMJ (2006)

This summer Europe has again been affected by a major heat wave and England triggered its heat wave response plan for the first time.1 In 2003, the impact of the heat wave in central France was unprecedented, with more than 14 000 excess deaths attributed to the 20 day event.2 This year, France has reported considerably fewer deaths, and the authorities can claim some credit for effective public health intervention. The United Kingdom experienced a more severe heat wave than in 2003, but the full impact on health is not yet known. Schools, offices, hospitals, and the transport infrastructure were all affected badly. Although much is known about the regulation of body temperature in healthy fit adults, little research has been undertaken on the social and environmental determinants of heat related mortality. People with psychiatric disorders, depression, cardiovascular and cerebrovascular conditions,3 and diabetes4 are at high risk of death during a heat wave. Specific drugs, such as neuroleptics and anticholinergics, can also impair thermoregulation.1 Susceptible people may be socially isolated and may have a mental illness or disability that limits their ability to care for themselves. The perception of ambient temperature is also poorer in elderly people, who do not always realise that they are becoming too hot.5 The passive dissemination of advice on heat avoidance is insufficient for health protection, and vulnerable people need to be actively identified and cared for.6

Public health measures implemented in Europe after 2003 have centred almost exclusively on heat health warning systems that forecast high risk weather conditions to trigger public warnings.7 Level 3 of the heat wave plan for England, triggered in early July, requires primary care trusts to “Commission additional care and support, involving at least daily contact, as necessary for at-risk individuals living at home.” But there is much confusion about identifying people at risk as well as the specific advice to be given. Cities in Italy are the most advanced in identifying and contacting vulnerable people at home during a heat wave. So far, no heat health system has been formally evaluated, and the effectiveness of individual interventions is unknown.6

The impact of heat waves also reveals important lessons about the care of the elderly and dispossessed in our society—in both the community and social care. The impact of heat waves in the United States is mostly confined to poor elderly people living in urban areas—who cannot afford air conditioning—and to the homeless. Elderly people in nursing and residential homes are more frail than those living independently or with family. Although such people have a higher risk of death than the general population, they should not have a higher risk of heat related death. Heat illness can be prevented by keeping the patient cool, hydrated, and with adequate salt balance. In the UK, air conditioning is rare in clinical settings, and hospital inpatients may also be exposed to high indoor temperatures and a high risk of heatstroke.8

One of the striking things about the heat wave in France in 2003 was that the high mortality was not detected for so long. In the UK, several indicators of heat morbidity are now monitored routinely using data from GP practices and NHS Direct. However, many countries in Europe, including the UK, do not have rapid access to mortality data from their registration systems. Some cities have solved this by bypassing the official system to get data directly from funeral homes within 24-48 hours.

The Euroheat network,9 coordinated by the World Health Organization in Rome, and funded by the European Commission, is developing good practice for health protection during heat waves as more countries develop heat health warning systems. An inter-agency approach—involving key health and social care providers as well as stakeholder groups—is needed. Heat wave systems also need to be better integrated within the disaster response agencies.

Much heat related mortality occurs outside of defined “heat wave” events.10 The best health protection measures are those that ensure long term changes in behaviour, such as the training of staff and carers and the development of appropriate care standards in residential homes (as has been implemented in Hessen, Germany9). Heat stress is also an occupational health problem for indoor and outdoor workers, and health and safety agencies need to be prepared for the impact of hotter summers. London's mayor is being particularly proactive with regard to climate change and is developing a statutory adaptation strategy to ensure that the infrastructure is appropriate for future climates. Climate change needs to be taken into account in health protection in Europe.11 The UK has recently had its hottest month since records began in 1660.12 The effects of climate change are appearing earlier than anticipated. It would be tragic if the main response to hotter summers is to install inefficient air conditioning and to miss the opportunity to develop effective and more equitable health protection measures for extreme weather.