New ASTM Standard Will Help Manage Heat Stress and Heat Strain in Foundries

Thomas Slavin

In May, ASTM International finalized its Standard Guide for Managing Heat Stress and Heat Strain in Foundries (E3279). The new standard provides an objective framework for recognizing heat stress and heat strain in foundries and provides for the use of best practices to manage heat exposures to minimize heat strain. 
The new standard spells out activities and responsibilities for foundry managers, supervisors and workers that will help prevent heat-related illnesses. Furthermore, the standard is based on successful best practices within the metalcasting industry. In addition, it could be used by regulators as a model approach for heat stress and heat strain management.

The AFS Safety and Health Committee was instrumental in providing research and recommendations during the development of the new ASTM standard.


Foundries have been melting metals at high temperatures in the U.S. since the industrial revolution and face unique heat management challenges. Radiant heat from molten metal, hot equipment and hot castings reach workers both directly (line of sight transmission) and indirectly as building surfaces absorb heat and reflect it.  Ambient temperatures, especially in the summer, are difficult to control in foundries. In addition, physical demands from foundry workloads increase metabolic heat build-up in workers.

If heat strain on a worker becomes excessive and is not abated, illness can result, including heat rash, heat cramps, fainting, heat exhaustion, heat stroke and even death. Excessive heat strain also increases the risk of workplace injuries, such as those caused by sweaty palms, fogged-up safety glasses and dizziness.
There is a key distinction between heat stress and heat strain. Heat stress is the net heat load to which a worker is exposed from the combined contributions of environmental factors (radiant heat, air temperature, relative humidity and air velocity), metabolic heat (workload), and clothing worn, which results in an increase in heat storage in the body. Heat strain is the body’s physiological response to heat stress. The body’s natural way to keep the core body temperature from rising to unhealthy levels is through an increase in heart rate and sweating. This physiological response to the heat load (external or internal) is how the body attempts to increase heat loss to the environment to maintain a stable body temperature.  

Individuals vary in their response to hot environments and in the effectiveness of their thermoregulatory mechanisms. Personal and environmental risk factors can impact an individual’s ability to beneficially respond to heat exposure. Each worker’s individual health and fitness status dictates the extent to which heat can be tolerated by the worker. 

Throughout its history, the foundry industry has implemented measures to protect its workers from the effects of excessive heat strain. However, little of the experience gained over the years has been documented. In 2018, the AFS Safety and Health Committee initiated a study to acquire and report successful heat management approaches to provide a resource for foundries to use when reviewing their approach to heat exposure control plans.

Regulatory Activity and Voluntary Standards

In recent years, there have been increased calls for heat stress regulation at both the state and federal level.  Many of these regulatory proposals focus on mandating engineering controls, such as air conditioning, to maintain an acceptable temperature and reduce heat stress. The 2018 AFS foundry study points to a more effective approach that uses heat management programs to reduce heat strain. 

The foundry approach to heat management formed the basis of the new ASTM standard. Development of the standard serves several purposes.
It provides useful guidance for foundries based on best practices by foundries that have a proven track record of success in managing heat stress and strain.  
It offers a roadmap for other industries and organizations that want to manage workplace heat issues.  

The standard serves as a stake in the ground for regulators developing a workplace heat standard. In fact, the National Technology Transfer and Advancement Act of 1995 requires regulatory agencies to use voluntary consensus standards in their regulations whenever practical. The ASTM standard thus provides experience-based input to regulatory agencies when developing standards for heat exposure control.  

Key Components of the ASTM Standard

A key part of the ASTM standard’s approach is managing heat strain, the body’s physiological response to heat stress. Trained and alert workers can perceive when heat strain is becoming excessive by recognizing the signs and symptoms that they experience. Because heat strain can cause a decline in alertness, coworkers and supervisors should also be attentive to the behavior of others and initiate action when warranted. 

The standard lists signs and symptoms that indicate the body has already passed the point where it can adequately compensate for the heat load being endured (see sidebar). Among those symptoms are “decline in alertness and vigilance” and “altered mental status.” These are not only red flags in terms of creating safety hazards for the worker and for others who rely on that worker’s performance, they could also lead to a situation where the worker will not recall his or her training, will not recall or be aware of the signs and symptoms or what to do in response to these signs and systems. Therefore, it is important that co-workers and supervisors are trained to recognize the early signs and symptoms of excessive heat strain and how to intervene, or heat illness is likely to follow. People respond to heat strain differently, and there is no single path or timeline from mild symptoms to serious heat illness.  


The standard outlines the following heat exposure control responsibilities:

Foundry management shall: 

  • Evaluate temperatures, and when necessary, issue heat alerts that initiate actions.
  • Make sure heat exposure measures and controls are in place and prescribed PPE is used.
  • Review heat exposure incident reports and approve corrective actions.

Human resources/safety staff shall:

  • Establish procedures and conduct training for employees working under hot conditions and for their supervisors and first responders.
  • Work with engineering to reduce heat exposure.
  • Evaluate areas that are significant heat sources as part of job safety assessments.
  • Oversee actions in response to reports of heat strain, including clearance to return to work.
  • Participate in worker orientation and training before assignment.
  • Choose PPE for specific situations.
  • Arrange medical services for evaluating employee capability to work with heat, treating workers with signs of heat illness, and participating in clearing workers to return to work.
  • Arrange for first aid responders to respond to signs of excessive heat strain.

Engineering shall:

  • Review heat exposures and seek ways to reduce heat.
  • Provide feasible control of process heat sources and ventilation.
  • Research and implement corrective actions in response to heat investigation reports.
  • Provide access to cool-off areas and hydration stations.

Workers shall:

  • Follow their training.
  • Prepare themselves to work under heat stress conditions.
  • Follow procedures for recognizing and reporting warning signs of heat strain in themselves and coworkers.
  • Supervisors shall:
  • Evaluate work conditions and heat exposure status, and take action based on heat exposure levels.
  • Provide input to worker training and evaluation before assignment.
  • Remove workers for job assignments who experience signs of excessive heat strain and interface with responders.

Program Elements

The standard also outlines the following heat stress and heat strain management program elements and lists options for addressing them.

A. Implement control measures as needed to address the following needs:

  • Only assign workers to heat exposures who are prepared for and can tolerate the exposures. This can be done through a combination of worker evaluation, training and acclimating; encouraging workers to monitor and report signs of excessive heat strain in themselves and others; or providing additional breaks and encouraging workers to take breaks they feel are needed.
  • Control heat sources to limit heat, use ventilation and work rotation.
  • Help workers to follow heat exposure control practices to control body heat. This can be done with additional hydration, PPE, cooling rooms, adjusting work schedules, reducing work time and workload, providing heat relief crews, or personal and portable cooling devices. 

B. Monitor heat and heat strain as follows, recognizing that the possible range of variations in heat stress, heat strain, and heat tolerance of workers means that exposure controls may not protect workers under all circumstances:

  • Check whether heat exposure control measures are functional and whether workers are following practices for working under heat conditions.
  • Measure temperatures and assess work efforts to evaluate heat stress impacts.
  • Assess potential for onset of heat strain through observation and communication with workers.
  • Establish triggering points and initiate actions based on monitoring results.

C. Take appropriate action and initiate preplanned strategies based on monitoring results that show heat stress conditions rising, onset of possible heat strain, malfunctioning controls, process upsets or workers not following proper practices:

  • Encourage workers to monitor themselves and others for signs of excessive heat strain.
  • Reduce heat stress levels by adding breaks or altering work assignments.
  • Provide additional air movement and cooling.

D. Establish a response protocol for reports of warning signs of the onset of excessive heat strain that may include the following:

  • Train first responders.
  • Respond to affected workers.
  • After evaluating and treating the worker, follow procedures for clearing worker to return to work or reassignment.
  • Identify and correct conditions responsible for occurrence.

A panel discussion of the new ASTM Managing Heat Stress and Heat Strain in Foundries will take place at the AFS Environmental Health & Safety Conference in Birmingham, Alabama, on October 11. A copy of the ASTM standard can be purchased at    

Click here to view the article in the digital edition of August 2021 Modern Casting.