Dost Pakistan - Digital Library

A civil defense siren is a form of siren used to warn civilians of approaching danger - a form of emergency population warning. Initially designed to warn city dwellers of air raids (air-raid sirens) during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes (tornado sirens). The generalized nature of sirens led to many of them being replaced with more specific warnings, such as the broadcast-based Emergency Alert System and the Cell Broadcast-ba...