How to Write an OSHA Heat Illness Prevention Plan

Texas ranks first in construction heat fatalities. From 2011 to 2023, 25 construction workers died from heat, more than any other state. In 2024, six more died, and OSHA cited four Texas employers. In Austin, the heat index exceeds 90°F on more than 100 days per year. For most of June, July, August, and September, every working hour outdoors is a high-heat-trigger day.

OSHA has a proposed Heat Illness Prevention Standard moving through rulemaking that would shift heat illness prevention from "recommended best practices" to enforceable employer obligations, specific thresholds, documentation requirements, and penalty exposure regardless of whether an incident has occurred. The rule has not been finalized, but OSHA is already inspecting under the General Duty Clause and its Heat-Related Hazards National Emphasis Program, and the agency's current expectations track closely with what the proposed rule would require. The first thing an inspector will ask for is your written Heat Illness Prevention Plan. Not a template you downloaded. Not a generic policy. A site-specific, documented plan that reflects the actual conditions of your worksite, built to the standard that's coming, not just what's enforceable today.

Here's exactly what that plan must contain, and how to build one that holds up.

Why the Written Plan Is Non-Negotiable

Current OSHA enforcement of heat illness still relies primarily on the General Duty Clause, a catch-all that requires employers to provide a workplace free from recognized hazards, backed by OSHA's Heat-Related Hazards National Emphasis Program, which directs inspectors to prioritize high-heat industries including construction. Once finalized, the proposed standard would replace that ambiguity with defined obligations: specific trigger temperatures, documentation requirements, and structured enforcement that applies regardless of incident history. Building your plan to that framework now means you won't be scrambling to rebuild it when the rule is finalized.

The written plan is the foundation of your entire heat illness program. Without it, every other effort, water stations, shade structures, toolbox talks, becomes difficult to defend in an inspection or after an incident. The plan must be:

• Written: not verbal, not informal, not "we've always done it this way"
• Site-specific: reflecting the actual layout, tasks, and exposures at each location
• Accessible: available to workers and their representatives on request
• Updated: revised when conditions, tasks, or personnel change significantly

A single corporate template applied to every project is not a site-specific plan. OSHA inspectors know the difference.

The Two Heat Trigger Temperatures

OSHA's proposed standard establishes two heat index thresholds that would activate specific employer obligations once finalized. Building your plan around these thresholds now reflects what inspectors are already looking for under current General Duty Clause enforcement.

80°F, Initial Heat Trigger

At 80°F heat index, the proposed rule would require you to:

• Provide cool drinking water (no warmer than 77°F) at no cost, at minimum one quart per worker per hour
• Ensure shaded or air-conditioned rest areas are accessible and workers are encouraged to use them
• Train workers and supervisors on heat illness recognition and emergency response procedures

90°F, High Heat Trigger

At 90°F heat index, additional obligations would activate:

• Mandatory scheduled rest breaks in shade or air-conditioned areas
• Implement a buddy system or direct supervisor monitoring of all workers throughout the shift
• Heightened observation of new or returning workers during their acclimatization period
• Two-way communication maintained between workers and supervisors at all times

Use OSHA's Heat Index App to monitor daily conditions at your site. For Texas contractors, plan for High Heat Trigger conditions from June through September as a baseline, not an exception.

The Six Essential Elements of a Written Heat Illness Prevention Plan

1. Identification of Heat Hazards

Walk every work area and document where heat exposure is highest. Look at:

• Tasks with high exertion: concrete work, roofing, trenching, material handling
• Areas with limited airflow: enclosed structures, below-grade work, confined spaces, areas between equipment
• Radiant heat sources: dark roofing surfaces, metal decking, machinery exhaust, reflective glass facades
• Shift timing: peak sun hours (10am–3pm) create meaningfully higher exposure than early morning or late afternoon work

The documentation must reflect your actual project, specific tasks, specific areas, specific conditions. A form listing "roofing" and "outdoor work" is not identification of heat hazards. It's a placeholder that will not satisfy an inspector.

2. Access to Water, Rest, and Shade

The plan must specify not just that water, rest, and shade will be available, but how, the actual logistics of your specific site:

• Water: cool (no warmer than 77°F), clean, and located within reasonable travel distance of work areas; during high heat conditions, minimum one quart per worker per hour
• Rest: shaded areas that block direct sunlight (not merely covered areas) or air-conditioned spaces if available, within reasonable walking distance of where workers are performing tasks
• Shade: natural or artificial structures sufficient for the number of workers who need to use them simultaneously, a single trailer at one end of a 400-foot site does not satisfy the requirement

3. Acclimatization Protocol

Acclimatization failure is the most common contributing factor in construction heat fatalities. New workers and workers returning from time off are at highest risk because they haven't built up the physiological tolerance to sustained heat exposure.

Your plan must include a written acclimatization schedule. OSHA's guidance:

• Day 1: 20% of normal workload or time in heat
• Days 2–7: increase gradually, reaching approximately 80% by day 7
• Days 8–14: continue building toward full workload
• Day 14+: full acclimatization for most healthy adults (some individuals take longer)

Supervisors must be trained to recognize workers who are struggling to acclimatize and to reduce their exposure accordingly. Skipping acclimatization is how healthy workers die. Document it, enforce it, and treat it as a firm requirement, not a suggestion.

4. Environmental Monitoring

Your plan must specify how your supervisor or competent person will monitor heat conditions throughout the workday:

• Method for checking heat index (OSHA's Heat Index App, on-site thermometer, credible local weather source)
• Frequency of monitoring, at minimum before work begins and at peak heat of the day
• Who is responsible and what authority they have to modify work schedules based on conditions
• How trigger thresholds are communicated to workers and crew leads in real time

5. Employee Training

Annual training is required for all workers and supervisors. Training content must cover:

• Signs and symptoms of heat exhaustion and heat stroke
• First aid procedures, including when to call 911
• The employer's heat illness prevention procedures and worker responsibilities
• Hydration requirements and why they matter
• Importance of acclimatization and how to self-report symptoms
• Worker rights, including the right to take shade breaks without fear of retaliation

Training must be conducted in a language workers understand. For bilingual crews, that means Spanish-language instruction, not a translated handout passed out on day one.

6. Emergency Response Procedures

Your plan must specify exactly what happens when a worker goes down from heat, before it happens. Define:

• Who calls 911, and at what threshold (any worker who has stopped sweating in extreme heat, is confused, has slurred speech, or loses consciousness is experiencing heat stroke, it is a medical emergency, not something to wait on)
• Who stays with the worker and begins active cooling (remove from heat, apply cool water or ice packs to neck, armpits, and groin)
• What cooling equipment is available on-site and where it is located
• How to communicate the worker's exact location to emergency responders
• Who notifies OSHA (fatalities require notification within 8 hours; in-patient hospitalizations require notification within 24 hours, and heat stroke hospitalizations are also OSHA-recordable incidents)

Recognizing Heat Illness Before It Becomes a Medical Emergency

Heat illness progresses fast. By the time a worker is confused or unresponsive, you're dealing with heat stroke, a life-threatening condition with a narrow treatment window. Train your entire crew to recognize the earlier stages and act immediately.

Heat exhaustion warning signs:

• Headache or dizziness
• Heavy sweating with cool, pale, clammy skin
• Nausea or vomiting
• Weakness, fatigue, or muscle cramps
• Irritability or unusual behavior

Heat stroke, call 911 immediately:

• Stopped sweating despite extreme heat
• Hot, red, dry or damp skin
• Confusion, disorientation, or slurred speech
• Loss of consciousness

The critical error supervisors make is waiting to see if a worker "just needs some water." A worker who has stopped sweating in 95°F heat is not going to recover with a water break. Get them out of the heat immediately, begin cooling, and call 911.

Low-Cost Field Solutions That Work

Your written plan must specify the controls you're providing. Not every effective heat control is expensive:

• Cooling towels: lightweight, reusable, and effective, keep a full cooler near the work area, not in the job trailer
• Hard hat neck shades: direct sun on the neck is a major heat load driver; a few dollars per worker
• Cooling skull caps: worn under the hard hat and soaked in cold water; workers who use them consistently report a meaningful difference in how they feel through the afternoon
• Electrolyte powder: water alone isn't sufficient during heavy exertion in heat, mix electrolyte packets into every cooler
• Pop-up shade structures: a canopy near the work area gives workers somewhere to cool down without walking off the site
• Extra water coolers: one cooler for 20 workers isn't enough; workers skip water breaks when the cooler is empty or far away
• Sunscreen station: put it out every morning; sunburn impairs the body's ability to regulate temperature
• Cooling vests: phase-change vests work for 2–3 hours and significantly reduce core temperature, worth the investment for workers in direct sun for full shifts
• Misting fans: effective in low humidity; position them at break areas where workers actually rest

The test of your heat illness prevention plan isn't whether these items appear on a list in a binder. It's whether workers are actually using them in the field. An unused shade structure and a warm water cooler are not heat controls.

How Often Should You Update Your Plan?

A written heat illness prevention plan is not a one-time document. Update it:

• At the start of each project season, before crews are working in heat
• When you mobilize to a new project with different site conditions, tasks, or workforce composition
• When conditions change significantly mid-project, such as when a phase opens new high-heat work areas
• After any heat illness incident or near-miss, however minor

Review the plan with crew members at the beginning of each heat season. Workers who know what's in the plan, what to watch for, what to do, where to go, are the ones who recognize heat illness in a co-worker at 2pm on a Friday in August.

Who Is Responsible for the Plan?

The written plan must name who is responsible for implementation at each worksite:

• A designated competent person who monitors heat conditions throughout the day and has clear authority to modify work schedules when thresholds are reached
• Supervisors and foremen who are trained to recognize heat illness in their crews and respond correctly without waiting for authorization
• A program administrator (safety manager or project manager) who keeps the plan updated, ensures training is completed, and maintains records

If you're using subcontractors, the plan must address who is responsible for their workers' compliance. As the general contractor, you are accountable for what happens on your site regardless of which employer's worker is affected.

Get It Right Before the Season Starts

An OSHA heat inspection following a reportable incident is not the time to discover that your written plan is a downloaded template with your company name pasted in. The plan needs to be done before crews mobilize, specific to the project, documented, reviewed with workers, and in the hands of every supervisor on site.

If you need help building a site-specific Heat Illness Prevention Plan or reviewing your existing program before your next project season, contact Greenberg Safety or call (512) 585-7070.