Human hair growth a new strand of hair begins to form. The rate or speed of hair growth is about 1.25 centimetres or 0.5 inches per month, or about 15 centimetres or 6 inches per year. The anagen phase is known as the growth phase. This is the phase where the hair physically grows approximately 1 cm per month. It begins in the papilla and can last from two to six years. The span at which the hair remains in this stage of growth is determined by genetics. The longer the hair stays in the anagen phase, the longer it will grow. During
Standard person patients to radiation. According to the International Commission on Radiological Protection's 1974 definition, “Reference man is defined as being between 20-30 years of age, weighing 70 kg, is 170 cm in height, and lives in a climate with an average temperature of from 10°C to 20°C. He is a Caucasian and is a Western European or North American in habitat and custom.” Standard person The standard person or reference person is a theoretical individual that has perfectly "normal" characteristics. This model is used for much research into radiation safety. For many years, the standard person was called reference man because