What action is required when a hazardous substance has been released?

The correct response focuses on the importance of understanding regulatory thresholds for hazardous substances. If a release occurs but the amount is below the reportable quantity, it does not necessitate immediate action or reporting under most regulatory frameworks. This is significant because the reporting requirements are designed to manage and mitigate risks from quantities that could potentially harm human health or the environment. When a substance is below the established threshold, the situation may be deemed manageable without emergency procedures, allowing responders to prioritize resources for more serious incidents.

In contrast to this, the other options endorse immediate actions or requirements that may not be necessary for minor releases. For instance, suggesting that immediate cleanup is essential regardless of quantity ignores the fact that smaller amounts may not impose any real threat. Similarly, claiming that investigation is mandatory for any release overlooks that smaller quantities might not warrant such resources. Lastly, stating that only documentation is required if there is no risk may fail to consider that certain substances still need reporting even if they are less of a concern, depending on jurisdiction. Thus, recognizing the role of reportable quantities provides a framework for appropriate and efficient responses to hazardous substance releases.