I am sorry, but none of the provided documents contain information about heat stress. Therefore, I cannot provide specific guidance on this topic based on the documents you provided. However, in general, heat stress in occupational health and safety refers to the condition that can occur when the body is unable to cool itself effectively, leading to a range of health problems. Preventing heat stress typically involves a combination of strategies, including providing adequate ventilation, ensuring access to cool water, scheduling work during cooler times of the day, providing rest breaks in cool areas, and using personal protective equipment (PPE) such as cooling vests. It's also important to train workers to recognize the symptoms of heat stress and to take appropriate action.