Code red warns of fire. At Children’s National Hospital in Washington, D.C., staff have added another: code dark, for a cyberattack.

7:15 a.m. — Widespread Code Red and Purple air quality, worst in years Residents in the Washington and Baltimore regions are awakening to their worst air quality in years.

Code Yellow” and “Code Red” are terms that put parents and students on high alert, but not everyone really knows what they mean.