when your office sends a message like the following:
To avoid confusion and concern, Washington HQ staff members should be aware that a movie company will detonate special effects explosives with 20 foot fire fire balls sometime between 9:30 am and 12 noon on Wednesday near the Key Bridge in Georgetown. While the offices are some distance from this area, staff members who may come to work late or go our to lunch early in that area should not be alarmed to hear the noise or see the fire ball/smoke. The special effects will only take two to three minutes.
I imagine is much worse in NYC or San Francisco.