In Brief

Clothing and personal protective equipment can restrict sweat evaporation, trap heat and add weight, increasing heat strain even in conditions that do not initially seem extreme.
Employers must not remove essential protection casually; they should control heat at source, reduce workload and select compatible equipment through a combined risk assessment.
Air temperature alone cannot describe risk. Radiant heat, humidity, air movement, work rate, duration and wearer factors all matter.
Personal cooling equipment can help selected tasks, but it has limitations and does not replace engineering control, recovery or supervision.

Protection Can Create a Second Hazard

A respirator, chemical suit, arc-rated garment or coverall may be essential. The same equipment can reduce evaporation, increase insulation and add physical effort. Treating heat and personal protective equipment (PPE) as separate assessments can leave workers protected from the initiating hazard but exposed to dangerous thermal strain.

This conflict appears in construction, asbestos work, foundries, spray booths, confined spaces, emergency response and cleaning. It also arises indoors, where process heat, poor ventilation and heavy work combine. The problem cannot be solved by telling workers to remove equipment or drink more water.

The employer needs a combined assessment that preserves the protection required for chemical, respiratory, impact, electrical or other hazards while reducing the heat burden by more reliable means.

Understand How the Body Loses Heat

The body exchanges heat through evaporation, convection, radiation and conduction. Heavy work generates metabolic heat. When surrounding air is hot, radiant sources are intense, humidity is high or air is still, heat loss becomes harder. Impermeable clothing can make sweating less effective because moisture cannot evaporate readily.

HSE explains that work rate, climate, clothing and PPE, and personal factors all contribute to heat stress. Symptoms may develop from reduced concentration and cramps through heat exhaustion to life-threatening heatstroke. Severe symptoms require immediate emergency action.

Comfort and heat stress are related but not identical. Discomfort can warn that conditions need attention; a worker can also experience significant physiological strain without a single universal temperature threshold being crossed. Assess the whole exposure.

Combine the Risk Assessments

List every item worn and why it is required. Consider garment insulation and permeability, respiratory resistance, equipment weight, coverage, fit and interaction. Include tools and loads carried, not only formally designated PPE.

Describe the task’s metabolic demand, posture, pace and duration. Record air temperature, radiant heat, humidity and air movement at the worker’s location. Consider whether the equipment becomes wetter or heavier, whether visibility deteriorates, and whether dexterity or communication is impaired.

Assess donning and doffing. Removing contaminated clothing can create exposure, while keeping it on during recovery can prevent cooling. Establish controlled changing, decontamination and rest arrangements. Where respirators are used, maintain respiratory protection and face-fit requirements.

Consult wearers. They can identify hot spots, chafing, fogging, loss of seal and practical barriers to taking breaks. Reports should prompt investigation, not an assumption that the worker is insufficiently resilient.

Apply British Duties Correctly

The Personal Protective Equipment at Work Regulations require suitable PPE where risks cannot be adequately controlled by other means. Suitability includes the conditions where equipment is used, ergonomic requirements, the wearer’s health and correct fit, alongside compatibility when multiple items are worn.

The Management of Health and Safety at Work Regulations 1999 require assessment of combined risks and arrangements to control them. The Workplace (Health, Safety and Welfare) Regulations 1992 address reasonable indoor temperature. COSHH, asbestos, respiratory protection, construction or confined-space duties may determine equipment that cannot simply be removed.

There is no general statutory maximum workplace temperature in Great Britain. Existing duties still require employers to manage foreseeable heat risk. HSE guidance is not itself legislation, but it provides practical evidence of recognised control principles.

Reduce Heat Before Changing PPE

Start with elimination and engineering. Remove unnecessary hot work, cool the process, insulate hot surfaces, shield radiant sources, improve ventilation or conditioned air, and use remote or mechanised methods to reduce physical work. Prevent heat from reaching the worker where reasonably practicable.

Separate people from heat using enclosures, screens or controlled zones. Check that ventilation does not spread hazardous dust, vapour or biological contamination. Where local exhaust ventilation is required for contaminant control, any cooling changes must preserve capture performance.

Reduce metabolic demand through lifting aids, task redesign and realistic pacing. Schedule work for cooler periods and provide recovery in a genuinely cooler place. Work rotation only helps if it reduces individual exposure without increasing the number of people exposed.

Select Equipment as a System

Review whether a less burdensome item provides equivalent protection for the assessed hazard. Consider material, weight, coverage, breathability and compatibility. Do not accept marketing terms such as “cool” or “breathable” without relevant performance information and a site trial.

Respiratory protective equipment selection begins with the contaminant, concentration, required protection factor, work and wearer. A lighter device is not suitable if it cannot provide the required protection. Powered equipment may reduce breathing resistance in some applications but introduces batteries, maintenance, training and other constraints.

Head, eye, hearing, fall and respiratory equipment can interfere with one another. Test the complete combination during representative movement. A cooling accessory must not break a respirator seal, reduce impact protection, obstruct vision or create entanglement.

Provide a suitable range and individual fitting. Equipment that is intolerable is more likely to be loosened or removed, but discomfort should trigger better risk control rather than informal non-use.

Evaluate Personal Cooling Carefully

Cooling vests, phase-change packs, circulating-liquid garments and air-supplied systems may reduce thermal burden for particular work. Selection should consider cooling capacity, duration, added weight, mobility, recharge, hygiene, decontamination and compatibility.

A cold pack can become dead weight after warming. A garment may cool the torso while leaving the head and limbs exposed. Condensation can affect comfort or electrical work. Shared equipment needs cleaning arrangements. Air-supplied cooling requires assured air quality and hose management.

Pilot equipment with workers in representative conditions. Define what success means: longer safe task time should not be the automatic aim. Better control may support lower strain, more reliable protection or safer recovery rather than extending exposure.

Personal cooling is a supplementary measure. It should not justify leaving an avoidable source uncontrolled or reducing necessary breaks.

Plan Work, Recovery and Hydration

Set work-rest arrangements from the combined assessment and revise them as conditions change. Recovery areas should allow safe removal or adjustment of equipment where contamination controls permit. Provide sufficient time for cooling, rehydration and equipment checks.

Make cool drinking water accessible and encourage frequent small drinks. For tasks where drinking is prohibited, plan opportunities before and after entry. Water provision does not compensate for excessive heat or unsustainable work rate.

Allow acclimatisation for new, returning and transferred workers. Protective ensembles may change the effective heat burden, so experience in ordinary work does not prove adaptation to encapsulated or high-workload tasks.

Supervisors need clear triggers and stop-work authority. Check lone-working communications and avoid relying on self-report where impairment may reduce judgement.

Train for Normal Work and Failure

Workers should understand why each item is required, how it changes heat loss, how to fit and inspect it, and when to report symptoms. Teach early action and emergency escalation without encouraging self-diagnosis.

Practise safe exit, decontamination and removal. A worker feeling unwell may need assistance, but helpers must not enter a hazardous atmosphere without protection. Emergency plans should reconcile rescue, contamination and cooling needs.

Inspect equipment, cooling systems and rest facilities. Record defects and corrective actions. Training records alone cannot show that arrangements work; observe tasks and ask workers to demonstrate checks.

Monitor the Combined Burden

Environmental or personal monitoring may help where the assessment needs better evidence. Define the question, use a suitable method and account for clothing and workload. Measurements should lead to predetermined actions rather than accumulating in a spreadsheet.

Review symptoms, near misses, heat-related stoppages, equipment non-use and production changes. Seek occupational-health advice for individual fitness and health surveillance where residual risk justifies it. Protect medical confidentiality.

Sysco Environmental can assess workplace heat stress and the interaction between environmental conditions, work rate and protective equipment. Our approach is to identify which factor drives risk and recommend controls that remain workable without compromising protection from the original hazard.

PPE can save lives, but its thermal cost must be designed into the job. The defensible solution is a system that controls heat, reduces effort, provides recovery and selects equipment as a compatible whole—not a choice between overheating and going unprotected.

Procurement, operations, occupational health and workers should review that system together. Seasonal changes, new garments, revised respiratory protection and altered production rates can all change the balance. When they do, reassess the combined exposure before relying on previous safe working times or monitoring results. Clear records should show the conditions assessed, assumptions made, action levels selected and person responsible for each improvement.

Could Your Protective Equipment Be Increasing Heat Strain?