Working with fire vs working with heat: key workplace safety differences explained

Fire and heat are often treated as the same workplace hazard. Both can cause serious injuries, damage property and disrupt operations. However, while similar and closely linked, they create different risks and require different safety controls.

Fire hazards involve ignition, combustion and the potential for fire to spread. Heat risks involve exposure to high temperatures, hot surfaces or hot environments, which can affect workers’ health, concentration and safety. Some activities, such as welding, can involve both and should be assessed separately.

Understanding the difference matters to anyone responsible for workplace safety. It can help organisations assess risks more effectively and choose the most appropriate controls.

Treating fire and heat as the same hazard can lead to gaps in risk assessments.

In this blog, we’ll cover:

• The definition of fire hazards in the workplace
• The definition of heat risks in the workplace
• The difference between working with fire and working with heat
• The main risks associated with each
• Common workplace activities that create fire and heat risks
• Why fire and heat hazards require different safety controls
• Practical ways to reduce risk

A fire hazard in the workplace is any condition, material, activity, or source of ignition that has the potential to start, fuel or spread a fire, putting people, property, or business operations at risk.

Heat risks in the workplace are the potential dangers and health effects that arise when workers are exposed to excessive heat, hot environments, hot surfaces, or high-temperature processes.

These risks can affect a worker's health, wellbeing, concentration, and ability to work safely.

The easiest way to think about it is that fire involves combustion, while heat involves exposure to high temperatures with or without fire.

Working with fire includes activities involving a naked flame, ignition source or the potential for combustion. Common examples include:

• Welding
• Cutting
• Soldering
• Roofing work involving blowtorches

Workers may be exposed to heat (but not necessarily with fire) from:

• Hot surfaces
• Machinery
• Steam systems
• Ovens
• Furnaces
• Any high-temperature environments

Some workplace scenarios involve heat and fire risks combined, whereas others deal with one. For example:

• A welder using a blowtorch may face both fire and heat hazards.
• A baker working near industrial ovens may face heat-related risks, despite not working directly with open flames.

While both hazards can cause burns, the wider risks and control measures are often distinct.

Fire hazards can result in burns, smoke inhalation, property damage and business interruption. If a fire spreads, it can put multiple workers, contractors and visitors at risk.

Heat hazards can also cause burns, but are more commonly associated with heat exhaustion, dehydration, fatigue and reduced concentration. These effects increase the likelihood of mistakes and accidents.

The Health and Safety Executive (HSE) emphasises the importance of managing excessive workplace heat, particularly during warmer months or in environments where workers are exposed to heat as part of their role. HSE guidance recommends taking practical steps to improve thermal comfort, particularly for employees working in hot temperatures. This may include increasing ventilation, providing access to drinking water, allowing suitable rest breaks and adjusting work patterns where needed.

A common misconception is that there is a legal maximum workplace temperature in the UK. However, this isn’t the case. Instead, employers are expected to provide a reasonable level of thermal comfort by assessing the risks where excessive heat could affect workers’ health or safety.

The infographic below summarises the key differences between fire hazards and heat risks in the workplace, including common activities, main risks and typical safety controls.

Hot work activities often create fire hazards. According to HSE guidance, tasks such as welding, cutting and grinding can generate sparks or heat capable of igniting nearby materials.

These risks are commonly found in construction, engineering, manufacturing and maintenance environments. Effective hot work safety procedures are essential for controlling ignition sources in these environments.

Heat hazards can arise in a wide variety of workplaces. Workers may be exposed to high temperatures in foundries, manufacturing facilities, boiler rooms and outdoor environments during periods of hot weather.

Many organisations will encounter both fire and heat hazards within the same working environment. Employers should identify which risks are present and assess each one appropriately.

Although fire and heat are often discussed together, the measures used to manage them can be very different.

Fire risk assessments focus on preventing ignition and reducing fire risks in the workplace. They also help ensure people can respond safely if a fire occurs. Controls might include removing combustible materials, using hot work permits, maintaining equipment and putting emergency procedures in place.

Heat-related risk assessments focus on protecting workers from heat-related illness and injury by identifying where excessive heat could affect people’s health, wellbeing or ability to work safely. Employers can reduce heat exposure by improving ventilation, providing drinking water, adjusting working patterns, introducing rest breaks and supplying suitable personal protective equipment (PPE).

Welding on a construction site is a good example. Sparks can ignite nearby combustible materials, creating a fire risk. The task can also involve contact with hot metal surfaces and exposure to heat. Although the activity is the same, employers should assess the fire and heat risks separately.

The first step is identifying which hazards are present in the workplace.

Employers should:

• Carry out suitable risk assessments
• Identify sources of fire and heat
• Put appropriate safety measures in place
• Train workers on safe procedures
• Review control measures regularly
• Monitor changes in activities, equipment and working conditions

The Health and Safety at Work Act 1974 places a duty on employers to protect the health, safety and welfare of their employees. Assessing fire and heat hazards separately helps organisations meet those responsibilities.

Where organisations regularly carry out hot work or manage significant fire hazards, fire safety training can help workers understand risks and apply suitable controls. Where employees are regularly exposed to hot or cold environments, workplace temperature training can also help organisations understand thermal risks and how to manage them effectively.

There is no legal maximum workplace temperature in the UK. However, employers still have a duty to manage risks to workers’ health, safety and welfare. If excessive heat could affect workers’ health, concentration or ability to work safely, employers should assess the risk and put suitable controls in place.

Welding can create both fire hazards and heat risks. Sparks, hot work and ignition sources can start or spread a fire, especially if combustible materials are nearby. At the same time, workers may be exposed to hot surfaces, radiant heat, burns, fatigue or dehydration. For this reason, fire and heat risks should be assessed separately.

Hot work usually refers to tasks that can produce heat, sparks or flames, such as welding, cutting, grinding or soldering. These activities can create fire hazards. Heat exposure is broader and refers to working in hot environments, near hot surfaces, around high-temperature equipment or during hot weather. Heat exposure may occur even when there is no flame or ignition source.

Employers can help reduce heat stress by improving ventilation, providing access to drinking water, allowing suitable rest breaks, adjusting work patterns, monitoring workers for signs of heat-related illness and providing appropriate PPE where needed. The right controls will depend on the work activity, environment and level of exposure.

Fire and heat are closely linked, but they are not the same workplace hazard.

Workplace fire risks centre on ignition, combustion and emergency response. Heat risks focus on exposure to high temperatures and their impact on workers. Recognising these distinct risks enables organisations to carry out more effective risk assessments, choose appropriate controls and create safer workplaces.