CEDA

CEDA (Civil Emergency and Defense Agency) is a fictional governmental organization in the Left 4 Dead universe. Matierials with the CEDA logo advising survivors can be found in numerous safe rooms.

According to descriptive text on Valve's store page for the CEDA Coffee Mug, CEDA has protected millions of Americans from the terrifying consequences of natural and manmade disasters since 1988.

"Safety Checklists" with a "CEDA" logo have been spotted around the now-deserted Fairfield, instructing residents to barricade themselves in their basements and wait for help to arrive.

They also instruct citizens to seal their windows and all other openings with plastic sheeting and duct tape, implying an airborne infection. However, one sign in the safe room at the end of The Subway has been written on by another survivor, saying "NOT AIRBORNE.".

It's left unexplained whether CEDA is involved with the military response to the infected, including the evacuations by the C-130 in Dead Air and APC in Blood Harvest. As there are many infected soldiers throughout the game, as well as abandoned Humvees in Riverside, it appears that the government is also unprepared for the virus.

CEDA appears to be based of the real-life FEMA, especially in it's advice to cover windows with plastic sheeting and duct tape.