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What you need to know about cooling PPE

By Rick Pedley

Understanding The Risks of Occupational Heat Stress
    Heat stress occurs when the body can no longer regulate its internal temperature due to excessive heat exposure. As core temperatures rise, the body reacts with symptoms ranging from mild discomfort (heat rash, cramps) to life-threatening (heat exhaustion and potentially fatal heat stroke).
    According to the National Institute for Occupational Safety and Health (NIOSH), several key factors contribute to occupational heat stress:
    High Air Temperatures and Humidity: Under these conditions, the air is saturated with moisture, making it harder for sweat to evaporate efficiently. This leads to heat buildup and increased risks of dehydration, heat exhaustion, and heat stroke, especially in physically demanding jobs or poorly ventilated environments.
    Direct Sunlight or Radiant Heat Sources: Hot asphalt, furnaces, and industrial machinery significantly increase thermal stress by raising the surrounding temperature and limiting the body's ability to cool itself. This type of heat exposure is particularly dangerous in confined or poorly ventilated spaces.
    Non-Breathable PPE: These can trap body heat and restrict airflow, which prevents sweat from evaporating and leads to rapid heat buildup. In extreme cases, prolonged wear can cause dangerous spikes in core body temperature, making workers more susceptible to heat stroke.
    Inadequate Hydration or Rest Periods: Without sufficient hydration, the body struggles to replace lost fluids, leading to fatigue, dizziness, and impaired cognitive function. Similarly, insufficient rest periods prevent workers from cooling down, causing heat stress to accumulate and potentially escalate into more severe conditions like heat exhaustion or heat stroke.
    Industries such as construction, agriculture, manufacturing, and oil and gas routinely expose workers to these conditions, making heat stress not just a seasonal concern but a daily reality.

Types of Cooling PPE and How They Work
    Various types of PPE have different mechanisms and ideal use-case scenarios. Safety managers should evaluate these options based on work conditions such as temperature, humidity, and duration of exposure.

Evaporative Cooling Vests
    These lightweight vests are soaked in water and worn over a base layer. As the water evaporates, it draws heat away from the body. They’re most effective in hot, dry environments where evaporation occurs quickly.
    • Pros: Affordable, reusable, easy to activate
    • Limitations: Less effective in humid conditions; can become heavy when saturated

Phase Change Cooling Vests
    These vests use phase change materials (PCMs) that maintain a constant cooling temperature (typically around 58°F) as they change from solid to liquid. They are ideal for humid environments or enclosed spaces where evaporative cooling is less efficient.
    • Pros: Effective regardless of humidity, stable cooling effect
    • Limitations: More expensive, requires refrigeration or ice packs to recharge

Neck Wraps, Bandanas, and Towels
    These accessories cool critical pulse points like the neck, wrists, and forehead. Some are evaporative, while others contain gel or PCM inserts.
    • Pros: Inexpensive, highly portable, can be worn with other PPE
    • Limitations: Limited coverage area; supplemental rather than primary cooling

Hard Hat Cooling Pads and Inserts
    These pads fit inside hard hats and are either evaporative or contain cooling gel. They help reduce heat buildup on the scalp and upper neck — areas with high heat sensitivity.
    • Pros: Integrated with mandatory head protection
    • Limitations: Cooling duration is shorter than vests or wraps

Moisture-Wicking Base Layers
    While not actively cooling, these garments play a key role by moving sweat away from the skin to promote natural evaporation. Many moisture-wicking base layers are designed to be worn under FR or arc-rated gear.
    • Pros: Improve comfort and reduce overheating under heavy PPE
    • Limitations: Passive cooling only; best used as part of a layered system

Cooling Hard Hat Pad with Neck Shade
    This evaporative cooling pad attaches inside a hard hat and extends down to shade the neck, reducing heat exposure from direct sunlight. It activates with water and provides cooling relief for several hours.
    • Pros: Easy to use, enhances head and neck cooling, reusable
    • Limitations: Requires periodic rewetting for continued effectiveness

Double Bib Hood Cooling Air System
    Designed for high-heat industrial environments, this system delivers cooled air directly to the worker’s head and neck through a double-bib hood. It connects to an external air source, making it ideal for extreme conditions like foundries or confined spaces.
    Many cooling PPE products are designed with field-specific features, such as adjustable fits, FR-rated materials, and compatibility with fall protection harnesses. Some are recharged with cold packs or water, while others can be reused throughout the day depending on ambient conditions.

Safety and Usage Considerations
    While cooling PPE enhances comfort and heat tolerance, it must never compromise a worker’s safety or interfere with essential PPE. Before implementation, safety managers should conduct a hazard assessment that accounts for:
    • Compatibility with FR, chemical, or electrical arc-rated clothing
    • Weight and mobility impact of cooling gear
    • Proper fit when combined with fall harnesses, visibility gear, or respiratory protection
    • Potential hygiene concerns with shared gear
    Cooling PPE is best used during outdoor or high-radiant-heat tasks such as roofing, paving, welding, trenching, or utility line work. NIOSH also recommends it for confined spaces and interior environments with limited airflow, such as boiler rooms and factory floors.
    Remember, providing proper training is essential. Workers should know how to activate, wear, and maintain cooling PPE properly. Make sure the gear is purchased from reputable brands or sellers. Equipment should also be inspected regularly for wear, mildew, or material breakdown, particularly in reusable gear.

Integrating Cooling PPE Into a Broader Heat Safety Plan
    Ultimately, cooling PPE should be viewed as one component of a layered safety strategy. Under no circumstances can they replace proper rest breaks, hydration, environmental monitoring, or worker education. However, when used correctly, it significantly improves worker endurance, productivity, and safety in high-heat conditions.
    As climate variability continues to affect workplace conditions across the country, now is the time for employers to evaluate their heat stress prevention protocols. While cooling PPE may not eradicate the hazards, combining its use with smart scheduling, training, and engineering controls can help keep workers safe, cool, and focused on the job.