HSE Hot Weather Guidance for Employers as Warm Weather Continues

The UK is currently enjoying an extended heatwave. July has consistently seen temperatures of more than 30°C in many parts of the UK. Temperatures are expected to reach in excess of 35°C next week, with some forecasters predicting highs of 43°C, which would be the hottest day ever recorded in the UK.

So, with temperatures ranging from the mid-20s to late-30s and even higher in some parts of the country, now is a good time for employers to familiarise themselves with temperature control regulations. In this article, we will cover what the law says about thermal comfort, with specific advice relating to heat stress, dehydration and cold stress.

The six basic factors

The HSE identifies the following six factors as the most important to regulating thermal comfort in the workplace. They can be broken down into environmental factors and personal factors.

Environmental factors:

  • Air temperature – the temperature in the air surrounding the body, usually given in degrees Celsius.
  • Radiant temperature – the heat that radiates from a warm object. Examples: fire, electrical fire, ovens, kilns, cookers, dryers, machinery, molten metals.
  • Air velocity – moving air in a workspace can heat or cool the environment.
  • Humidity – refers to heated water that has evaporated into the surrounding environment.

Personal factors:

  • Clothing insulation – wearing too much clothing/PPE can lead to heat stress. Clothing without suitable insulation can lead to hypothermia or frostbite.
  • Metabolic heat – is derived from undertaking physical activity. A person’s sex, size and weight should be factored into their metabolic comfort in the workplace.

Workplace temperature controls

To keep employees safe, the HSE recommends employers maintain a reasonable working temperature in workrooms – usually at least 16°C, or 13°C for strenuous work (unless other laws require lower temperatures).

When employees are too hot, there are several steps employers can take:

  • Control the environment – use air conditioning in hot weather and adjust the heating on colder days, humidify or dehumidify the air as necessary, increase air movement with ventilation, exclude drafts.
  • Separate the source of heat from the employee – put up barriers and or insulation to shield employees from the source of discomfort.
  • Control the task – reduce the time period that employees are exposed to extreme conditions, control shift lengths and the amount of work each employee does, use lifting aids to reduce employee workload in extreme environments.
  • Control the clothing – ensure employees wear appropriate PPE clothing, consider alternative uniforms or employee adaptions to improve comfort, provide layers to allow employees to make adaptions where necessary.
  • Allow behavioural adaptions – if possible, remove restrictions that allow employees to make minor adaptions to their clothing and work rate, provide warm up or cool down areas, provide heaters and fans, allow windows to be opened.
  • Monitor the employee – train and supervise employees, seek medical advice when employees have health conditions, are pregnant, or have a disability, review risk assessments when alerted to employee pregnancies.

Administrative controls 

Consider planning work at more temperate times and implementing rest periods built into work schedules. You might also consider allowing employees to have flexible hours to allow them to work during the cooler periods of the day during high temperatures. Through simple administrative controls you can keep your employees safe in warm weather.

Engineering controls

The HSE recommend that heating controls should be the primary solution for controlling temperature. While initial costs may be high, the value is recouped through improvements to worker productivity.

Heating systems

Various systems can be implemented:

  • Hot air-based heating systems
  • Water-based radiators and central heating
  • Electrical heating systems
  • Overhead heating systems
  • Underfloor heaters

Cooling Systems

Cooling systems include:

  • Ventilation
  • Air movement
  • Air conditioning
  • Evaporative cooling
  • Thermal insulation

Health, safety & environmental consultancy

Contact us today for health, safety and environmental advice and training. Consider whether your risk assessments are up to date, and most of all stay cool during this hot summer!


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