A new study by researchers at the Center for Mass Destruction Defense (CMADD) at the University of Georgia details the catastrophic impact a nuclear attack would have on American cities and the inability of the nation’s current medical system to handle casualties.

It also suggests what the authors said are much needed yet relatively simple interventions that could save tens of thousands of lives.

Among the study’s findings:

A 20-kiloton detonation would leave debris tens of feet thick in downtown areas with buildings 10-stories or higher. Roughly half of the population in downtown areas would be killed, mainly from collapsing buildings. Most of those surviving the initial blast in downtown areas would be exposed to a fatal dose of radiation.

While the main effects from a 20-kiloton explosion would be from the blast and the radiation it releases, a 550-kiloton explosion would create additional and substantial casualties from burns. Such an explosion would superheat the blast zone, causing buildings to spontaneously combust. Mass fires would consume cities, reaching out nearly four miles (6.3 km) in all directions from the detonation site.

A 550 kiloton detonation in New York would result in a fallout plume extending the length of Long Island, resulting in more than 5 million deaths.

A 550 kiloton detonation in Washington, D.C. would destroy hospitals in the District, but its fallout plume would also incapacitate hospitals in Baltimore, nearly 40 miles away.