What is an essential action if you can safely do so during a spill?

Stopping the leak during a spill is crucial because it directly addresses the source of the contamination. By halting the leak, you prevent further release of hazardous substances into the environment, minimizing the impact on surrounding ecosystems and public health. This action is typically prioritized over other responses as it sets the stage for effective mitigation of the spill's consequences.

While clearing the area of people, monitoring air quality, and starting cleanup procedures are important actions, they may not be as effective without first stopping the leak. Clearing the area ensures safety but does not prevent the spill from worsening. Monitoring air quality is vital for assessing exposure risk but does not address the ongoing leak. Cleanup procedures are essential for recovery but can only begin effectively once the source of the spill is contained. Thus, stopping the leak is the first step in an effective response strategy.