The sudden and violent expansion of gases or liquids due to an internal chemical reaction or other source of pressure can cause damage to life and property. Some materials, such as fireworks and dynamite, are designed to be exploded with certain safeguards. When the safeguards are not in place, the explosion can be dangerous. Potentially harmful effects are burns, broken bones, blast injuries due to air pressure change, shrapnel and flying debris, asphyxia due to breathing poisonous gases or particles in the air, and shock.
Explosive gases include acetylene, butane, coal gas, methane and propane. Other explosive objects are bombs, grenades, rockets, land mines, marine mines, depth charges, artillery shells, missiles, torpedos and munitions in general. Shrapnel fragments produced by bullet, weapon, breech block, vehicle or aircraft explosions are also very injurious.