Under what circumstances can the AHJ increase required separation distances?

The correct choice highlights that the Authority Having Jurisdiction (AHJ) can increase required separation distances in response to unusual or safety-threatening conditions. This provision is crucial for ensuring safety during fireworks displays, as it allows the AHJ to proactively address unforeseen risks that may arise due to environmental factors or other situational hazards.

For instance, if strong winds are present that could alter the path of fireworks or increase the likelihood of debris landing in areas where people might be located, the AHJ has the discretion to expand the safety zones to mitigate these risks. This flexibility is essential for maintaining safety standards and protecting both spectators and personnel involved in the event.

In contrast, other circumstances like poor weather, advice from the display crew, or the presence of spectators may not directly justify an adjustment to separation distances. While these factors are certainly important considerations, they do not inherently signal unusual or safety-threatening conditions that would necessitate an increase in separation distances as outlined in the NFPA 1123 guidelines. The ability to adjust based on significant safety concerns is what makes the AHJ’s authority so vital in the context of fireworks display safety.