RADIATION HAZARDS : We are sure that you would have studied about electromagnetic radiation during your studies at the school. You would recall that in electromagnetic radiation, the electric and magnetic components oscillate in mutually perpendicular directions as well as to that of the direction of propagation, Figure It is characterised by parameters like wave length (A) which is the distance between two crests or troughs and frequency (v) which is the number of waves per second.
The energy of radiation is given by the formula:
C E = hv = h- ; h is Planck's constant and c is velocity of light.
The wavelength of a radiation can be as small as less than a picometre (10-I2m) or as high as a kilometer (km) or even more. As we see from the formula, the energy of radiation will decrease with increase in its wavelength. The hazardous nature of the radiation is manifested on its interaction with matter.
On the basis of interaction with matter, radiations may be divided into two broad groups - ionising and nonionising. The nonionising radiations cannot change the nature of atom, but can be highly hazardous. They include ultraviolet and infrared radiations, ultra sonics, light (e.g. from lasers) and microwaves. The ionising radiation changes the atomic structure of a substance and can be classified into three major types - alpha (a ), beta (β) and gamma (y). The International Ionising Radiation symbol is used to indicate the presence of intermittent or continuous ionising radiation, Figure. It is usually black, on a yellow background.
The energy of the radiations absorbed when these ionising rays pass through living organisms can cause immense damage. The radiations affect human beings in a number of ways. They can cause cancer, genetic mutations, skin reddening etc. Cells which divide, such as those which produce the red blood corpuscles are particularly susceptible. Effects on reproductive cells are cumulative and genetic damage may result. You must therefore exercise great care when using, storing or disposing of such materials.