Managing exposure to heat stress is among the safety and health considerations that need to be addressed in a successful foundry operation. Heat stress is generated both by heat produced inside the body due to metabolic activity occurring in the muscles, and by thermal environmental conditions surrounding the body.

The body’s response to heat stress is termed “heat strain.” Heat strain taxes the capability of the human body to control its internal temperature. When heat strain becomes excessive, heat disorders result.

Heat-related disorders include heat rash, cramps, fainting from blood pooling, heat exhaustion and collapse and possibly fatal heat stroke. An effective foundry strategy is needed to manage heat stress during work activity and prevent heat related disorders. The strategy requires commitment and participation on the part of foundry management, workers and their supervisors, as well as staff representing health and safety, process operations, facilities and maintenance—all focused on the well-being of the workforce.

Personal Preparations for Work Activity Involving Heat Stress
Responsibilities need to be assigned for planning and implementing the program, with outside medical and industrial hygiene support utilized as needed.

Health clearance and ongoing health surveillance needs to be a prerequisite for work activities that can elevate heat stress to assure no one is placed at unacceptable risk of developing a heat disorder. Due to their health state or physical condition, not all workers in a foundry may be capable of performing work involving heat stress in a safe and healthy manner.

Training should focus on workers and their supervisors, so they increase their understanding of:

• How the body releases its internal heat buildup.
• How heat strain challenges the body’s ability to control its internal temperature.
• What role workers and supervisors must assume in preventing heat disorders.
• How to become properly acclimatized to heat and maintain hydration and electrolyte balance.
• The signs of impending rise in heat strain.

Managing Heat Stress During Work Activity
Managing heat stress requires addressing the following challenges:

• The potential added heat stress caused by personal protective equipment (PPE) used to protect workers from molten metal sparks and splashes, from explosions and from radiant heat due to close proximity to molten metal sources.
• Consistent practices of staying hydrated, having ready access to water and electrolytes and having natural (or enforced) breaks to hydrate and urinate.
• Proper ergonomics, limiting exertion levels through use of mechanical assistance devices and scheduling work appropriately to provide for work/rest regimens.
• Isolating heat sources to the extent feasible through containment and control of waste process heat and through controlling radiant heat input to the worker’s body caused by line-of-sight contact between molten metal surfaces and workers’ bodies.

Self-Determination and Response Based on Early Warning Signs of Excessive Heat Strain
Workers who are properly prepared for heat stress conditions can be trained to recognize and immediately respond to physical signs of excessive heat strain, prior to the onset of heat related disorders.

Examples of early warning signs of a level of excessive heat strain which could result in heat disorders include profuse sweating, increased heart rate, abnormal physical sensations such as dizziness, nausea, and blurred vision, fatigue, diminished work performance and decline in alertness and vigilance.

A cooperative attitude needs to exist in the workplace, so workers know they are free to respond to early warning signs of excessive heat strain and staff know they are required to become involved and support the worker in responding to the situation.

If a worker recognizes early warning signs of excessive heat strain, or if a coworker or supervisor observes these signs in that worker, the work activity of that individual should be interrupted. The worker should immediately move or be taken to a prepared location where an assigned individual can assess the situation and direct actions to be taken.

To the extent that workers and supervisors respond to early warning signs of excessive heat strain, heat disorders are for the most part preventable.

Heat Strain Assessment and Recovery
At the prepared heat stress response location, the worker should be immediately treated by a person on staff who is trained and available to perform these duties:

• Meet the worker and guide all actions while at the location.
• Listen to their reported symptoms and assess the seriousness of the situation.
• Take heat strain measurements (e.g., core temperature and heart rate).
• Apply first aid as needed, including cooling the worker and addressing hydration and electrolyte balance issues.
• Get medical assistance, including sending the worker to a hospital, as needed.
• Maintain records of services provided during the response.

Planning, installation and staffing for the assessment and recovery steps should rest in the hands of a designated, responsible person, preferably the Safety and Health Director.

Follow-Up of Heat Strain Assessment and Recovery and Clearance to Return to Work
Clearance to return to work should be preceded by medical review of the incident, risk reassessment and possibly retraining. Inputs needed for risk reevaluation include:

• Past history of the worker in heat stress situations.
• Current health and fitness state of the worker.
• Feedback from the worker and response personnel.
• Current degree of heat acclimatization.
• Ability to maintain hydration and electrolyte balance.
• Energy requirements of the job.
• Environmental conditions associated with the work.

Click here to see this story as it appears in the May 2019 issue of Modern Casting