What type of emergency rescue equipment must be readily available in hazardous conditions?

In hazardous conditions, having a safety harness and line readily available is crucial for ensuring the safety of workers. These items are designed to prevent falls or accidents when operating in high-risk environments, such as those involving excavators or other heavy machinery. The safety harness secures the operator to an anchorage point, providing stability and preventing falls that could result in serious injuries. A safety line enhances this protection by acting as a lifeline, ensuring that if a fall occurs, the operator can be safely caught or retrieved.

While other options like heavy lifting machinery, portable fans for ventilation, and first aid kits are important in specific situations, they do not directly contribute to the immediate safety of the operator in potentially life-threatening scenarios related to falls or loss of control. The emphasis on a safety harness and line reflects best practices in occupational safety and health regulations, highlighting the importance of personal protective equipment in preventing accidents and saving lives.