1. Atomic Bombs on Japan: The Human Cost

2. How to atomic bombs work?
Nuclear fission produces the atomic bomb, a weapon of mass destruction that uses power released by the splitting of atomic nuclei.
When a single free neutron strikes the nucleus of an atom of radioactive material like uranium or plutonium, it knocks two or three more neutrons free. Energy is released when those neutrons split off from the nucleus, and the newly released neutrons strike other uranium or plutonium nuclei, splitting them in the same way, releasing more energy and more neutrons. This chain reaction spreads almost instantaneously.

3. Death Rates
Over 90% of persons within 1,600 ft. of ground zero in both cities (Hiroshima and Nagasaki) died. 
At almost one mile, over 2/3 were casualties, and 1/3 died. 
Of those at a distance of 1.2 mi., half were casualties, 10% of whom died. 
Casualties dropped to 10% at distances over 2.4 mi.

4. Immediate Effects
Most victims in Hiroshima and Nagasaki died instantly or soon after the dropping of the atomic bombs, due to the intense heat that was released.
Severe thermal burns became the most visible evidence of the bombs, and this was carried by survivors for the rest of their lives.

5. Nuclear Shadow
Immediate radiation of the blast bleaches everything it hits, similar to how UV rays cause sunburns on your skin at the beach.
Human bodies close to the blast sites in effect shielded those rays emitted from the atomic bombs, creating a “shadow” behind them.
Many of these “shadows” still exist today.

6. Long-term Effects of the blasts
Radiation injury penetrates deeply into human body and injures cells, and thus molecules, resulting in cell death, weakened cell division, abnormalities of intracellular molecules and membranes.
Cancer: Leukemia (cancer of the blood cells) and other forms of the disease affected the future lives of survivors.
Instances of Leukemia peaked in the early 1950s, over five years after the bombs were dropped.
Genetic Damage: Some survivors of the blasts would go on to have children with abnormalities, more so than the general population.