Deaths due to heat-related illness

Dyddiad y datganiad:
13 October 2025

FOI reference: FOI-2025-3147

I write to you with a Freedom of Information Request (FOI) to review the number of and content of Medical Certificate of Cause of Death (MCCD's) with any of the below clinical titles listed within the MCCD, either at 1a, 1b, 1c, 1d or part 2. 

The immediate, direct causes of death or contributing factors we are interested and would like to request their MCCD's for are:

  1. Heat related Illness
  2. Exertional Heat Illness
  3. Non-Exertional Heat Illness
  4. Classic Heat Illness
  5. Heat Illness
  6. ​​​​​​​Heat Stroke
  7. ​​​​​​​Exertional Heat Stroke
  8. ​​​​​​​Non-Exertional heat Stroke
  9. Hyperthermia

The purpose for this is as part of a wider study looking at the current healthcare burden of Heat related illness, in particular Exertional Heat Illness on the UK healthcare system.

We said

Thank you for your request.

Our mortality data comes from the information collected at death registration. All of the conditions mentioned on the death certificate are coded using the International Classification of Diseases, Tenth Revision (ICD-10). From all of these causes an underlying cause of death is selected using ICD-10 coding rules.   

The underlying cause of death is defined by the World Health Organization (WHO) as:  

  • the disease or injury that initiated the train of events directly leading to death, or
  • the circumstances of the accident or violence that produced the fatal injury  

We hold some of information you have requested. However, the ICD-10 classification does not differentiate between exertional and non-exertional heat illness. 

We can provide the number of deaths where the following conditions have been mentioned on the death certificate through our bespoke services route: 

  • T67.0 Heatstroke and sunstroke 

  • T67.1 Heat syncope 

  • T67.2 Heat cramp 

  • T67.3 Heat exhaustion, anhydrotic 

  • T67.4 Heat exhaustion due to salt depletion 

  • T67.5 Heat exhaustion, unspecified 

  • T67.6 Heat fatigue, transient 

  • T67.7 Heat oedema 

  • T67.8 Other effects of heat and light 

  • R50.9 Fever, unspecified 

Bespoke services are subject to legal frameworks, resources and agreement of costs. If you would like to request this bespoke dataset, please contact health.data@ons.gov.uk to discuss your enquiry further. Please note, there will be a charge for this work which would be subject to our charging policy. 

As this information is reasonably accessible via another route, even if only accessible on payment, Section 21(2)(a) of the Freedom of Information Act 2000 (FOIA) applies.

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