Heat Stress at the Foundry: A Worker Who Won't Stop Working
It is July, and the indoor temperature on the furnace floor of a small aluminum foundry reaches 38°C (100°F) with radiant heat from three open furnaces. A 47-year-old pourer with 12 years' tenure has hypertension treated with a thiazide diuretic and a BMI of 34. He works a 10-hour shift with one 30-minute unpaid lunch. During your walk-through he is sweating heavily, complains of a headache, and tells you he "just needs to push through" because his crew is short-staffed. His oral temperature is 37.9°C, heart rate 108, and he reports dizziness when standing. The plant has no written heat illness prevention plan, no acclimatization schedule for new hires, and no cool-down area. The supervisor says "we've never had a problem."
1. Differentiate heat exhaustion from heat stroke in this worker and state your immediate clinical and administrative actions.
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Clinical reasoning. Heat stroke is defined by core temperature typically above 40°C plus central nervous system dysfunction (confusion, ataxia, seizures, collapse); heat exhaustion presents with heavy sweating, tachycardia, headache, dizziness, and core temperature usually below 40°C without altered mental status. This worker has 37.9°C, intact mentation, and heavy sweating, so heat exhaustion is most likely. However, oral temperature underestimates core temperature, and his thiazide diuretic plus hypertension and high BMI increase risk of progression and electrolyte disturbance. Dizziness on standing suggests volume depletion.
Immediate actions. Move him to a shaded, air-conditioned space; loosen clothing; apply cool wet cloths; encourage oral rehydration with an electrolyte-containing beverage if he is alert and not vomiting; recheck vital signs and mental status every 15 minutes. Do not allow return to work that shift. Escalate to emergency care if mental status changes, temperature rises, he stops sweating, or he cannot keep fluids down. Document findings and notify the supervisor in writing.
Administrative actions. Remove him from the heat source for the remainder of the shift, arrange a same-day or next-day occupational health follow-up, and communicate with his primary care provider about diuretic use during heat exposure. Record it as a heat-related incident even though it is not recordable unless it meets recording criteria, and use it to trigger a written heat plan.
2. Design the elements of a heat illness prevention program for this plant, prioritizing what can be implemented within 30 days.
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Immediate (0–30 days). (1) Written heat illness prevention plan with a named responsible person. (2) Water: cool water available within arm's reach, encouraged at least one cup every 20 minutes. (3) Rest: shaded or air-conditioned break area; mandatory rest cycles based on measured heat index, with more frequent breaks above 35°C. (4) Acclimatization: new and returning workers start at 20% of heat-load duration and increase by no more than 20% per day over 1–2 weeks. (5) Buddy system and supervisor training to recognize symptoms. (6) Emergency response: who calls 911, how the worker is cooled while waiting.
Engineering and work practice (30–90 days). Local exhaust ventilation at furnaces, reflective shields, spot cooling, reducing radiant load, scheduling heavy work earlier in the day, and rotating tasks. Consider cooling vests for the pourer.
Surveillance. Pre-shift symptom check on high-heat days; individual risk assessment for workers on diuretics, antihypertensives, or with prior heat illness. Track incidents and near misses.
Evaluation. Measure heat index at the work station, audit break compliance, and review incident rates quarterly.