This Headache Cannot be Treated with Aspirin- Beware of Warehouse Workers’ Headache!

A severe headache is the most common symptom of CO poisoning. In warehouse environments, repeated exposure has led to a condition informally called Warehouse Workers’ Headache Syndrome.

Many warehouse operators assume that propane forklifts eliminate CO risks. While propane burns cleaner than diesel or gasoline, it can still produce carbon monoxide if:

• The forklift is poorly maintained
• Catalytic converters are missing or malfunctioning
• The engine is left idling indoors near ventilation intakes

At a small storage warehouse, a gasoline forklift was converted to propane due to safety concerns. The forklift was left idling near an air intake, causing CO exposure to 3 male and 27 female employees. Some were still suffering neurological effects—numbness in limbs, confusion, memory loss, persistent headaches—two years later (Ely, Moorehead & Haponik, 1995).

The layout of the warehouse is shown below:

Investigators measured the CO concentration in the room at 386 ppm while the propane forklift idled. Once turned off and ventilated, levels dropped to 3 ppm within minutes, demonstrating how quickly CO can accumulate and dissipate indoors.

Electric forklifts are completely safe from carbon monoxide because they produce no combustion emissions.

A tragic example illustrates the danger of combustion-powered forklifts in enclosed spaces. In one warehouse operation, a propane-powered forklift was used to load pallets of blueberries into a refrigerated truck. During the operation, two employees lost consciousness due to carbon monoxide exposure, and one worker later died with a carboxyhemoglobin (COHb) concentration of 60%, a level associated with severe and often fatal poisoning. Following the incident, the propane forklift was replaced with an electric model, eliminating the CO hazard associated with that equipment.

The authors of this investigation (Hirsch, Langley, and McDaniel, 2016) emphasized that while electric forklifts are the safest option for indoor environments, not all workplaces can immediately replace combustion-powered machinery. In such situations, employers can significantly reduce the risk of carbon monoxide exposure by implementing several practical safety measures.

These precautions are not limited to propane forklifts. Similar risks exist with portable propane heaters and gas-powered equipment, including heavy-duty saws, grinders, and floor polishers used indoors or in poorly ventilated environments. Without proper ventilation and monitoring, these devices can also generate dangerous carbon monoxide levels and place workers at serious risk.

Repeated CO exposure can cause chronic neurological symptoms, including headaches, dizziness, confusion, memory impairment, and numbness. Early identification of Warehouse Workers’ Headache Syndrome is essential to prevent serious injury or death.

The encouraging reality is that this hazard is largely preventable. Proper equipment maintenance, improved ventilation, worker education, and the installation of inexpensive carbon monoxide detectors can dramatically reduce the risk.

With awareness and simple safety measures, the dangerous headache caused by carbon monoxide exposure can disappear—just as quickly as the gas itself does when a warehouse is properly ventilated.

References

Ely, E.W., Moorehead B., and Haponik, E., “Warehouse Workers’ Headaches: Emergency Evaluation and Management of 30 Patients with Carbon Monoxide Poisoning”. American Journal of Medicine, 98: 145-154, 1995

Gallagher, F., and Mason, H.J., “Carbon Monoxide Poisoning in Two Workers Using an LPG Forklift Truck Within a Coldstore”, Occupational Medicine, 54: 483-488, 2004

Hirsch, A.E., Langley, R.L., and McDaniel, J.S., “Carbon Monoxide Poisoning from Forklift Use During Produce Packing Operations”, Journal of Agromedicine, 23: 132-135, 2016

Kucera, H.L., Mewes, J.R., and Orr, P.H., “Carbon Monoxide from Engines in Warehouse Operations”, American Potato Journal, 49: 93-97, 1972