A nuclear explosion manifests itself in the air as an intense flash of lighting which is thousand times brighter and accompanied by intense heat radiation, sufficient to set fire to light combustible material within fourteen km. The emanating x-rays can be lethal at a distance of 3 km. People nearby will be killed. The flash is succeded by a "fireball" in the air and has a blinding effect with intense radiation. People looking at it at daytime would be blinded. Within ten km. of "ground zero" all exposed body parts will be burnt. The intensity of damage would depend upon weather and time of the day . For example, darkness dilates the pupils of the eyes increasing the probability of severe eye damage from the flash. The blast would be so powerful that people in the open would be picked up and hurled.

The first flash would start many fires which will be accentuated by burst fuel tanks, gas mains, and collapsed buildings etc. The temperature even in basements and bomb shelters rises above lethal levels, and all available oxygen is used by the fire.

Delayed Radiation ("fallout")

A nuclear explosion, results into a radioactive surrounding. An "air-burst" gaseous radioactive products rising with the fireball. It may be a rainstorm containing radioactivity, as there was at Hiroshima.

Black Rain

Rescue Problems

It is imposible to conduct rescue operations if a bomb explodes in the heart of the city due to structural damage, failure of infrastructure like electricity, water, communication etc. The city may become inaccessible to the outer world, paralysing rescue services. The destroyed city would be radioactive, making rescue work, hazardous for the rescuers.

Medical Problems

Around one third of the inhabitants would be killed instantly or fatally injured, one third seriously injured, and the rest uninjured or only slightly injured. Non - availability of blood and radioactivity in patients would add to the hardships and those who could have been saved would also die due to absence of adequate medical help.

An enormous crater four hundred metres across and seventy metres deep would result on a bomb explosion at ground level. The resultant debris would be radioactive. The radiation doses received would be lethal to anyone in the open. The number of immediate deaths might be about half of those from an air-burst, but unless survivors could find protection from fall-out there would be many deaths from radiation sickness days or weeks after the bomb.

Thousands would be killed and severely injured. Due to absence of a firestorm, rescue might be successful. The area will become extremely radioactive and impossible to inhabit for many years. There would be a number of deaths from radiation sickness.

The neutron bomb emits a spray of neutrons that is lethal for a distance of a few hundred metres. These neutrons, unlike the X-rays from the explosion, penetrate a considerable thickness of concrete or steel protection. They are designed for "battlefield" use, not for use against cities.

The most important late effect of radiation exposure, however, is an increased incidence of cancers and leukaemia of the types that occur naturally in unexposed individuals. Considerable increases in leukaemia and of cancers of the thyroid, the lung, and the female breast have been recorded.

Laboratory animals whose entire bodies are exposed to radiation in the first half of life suffer a reduction in longevity that increases in magnitude with increasing dose. This effect was mistaken as a manifestation of accelerated or premature aging. Shortening due to diseases other than cancer has not been observed.

Interaction with ionizing radiation results into temporary or permanent impairment of cellular function, or the cell may be destroyed. The severity depends on the type of radiation, absorbed dose, the rate of absorption and the radiosensitivity of the tissues.

Radiation can break the chromosome fibre and interfere with the normal segregation of duplicate sets of chromosomes to daughter cells, thereby altering the structure and number of chromosomes in the cell by breaking both strands of the DNA molecule. Hence, the cell may get altered or die in division. A few chromosome that don't heal may lead to the loss of an essential part of the gene complement called Gene deletion.

Effects on the growth and development of the embryo

The tissues of the embryo are highly radiosensitive, the type and frequency of radiation effects depending on the stage of development of the embryo during exposure. Earlier exposure in embryonic life may kill the embryo than cause a congenital malformation, unlike exposure at a later stage which is more likely to produce a functional abnormality in the issue.