Heat has prominent effects on physiological parameters.Along with the biochemical factors (ALT, AST, ALP, Total proteins and Albumin), blood formed elements (RBCs, WBCs and Platelets) are also affected by the long hours of heavy heat loads. Blood electrolytes also show significant variations by heat stress leading to the metabolic acidosis. Increased blood flow towards skin is promoted by the release of vasodilator from the sweat glands. Heat may also cause lethal damages to vital organs like heart, liver and kidney etc. Industrialized countries face major hazards in the form of occupational diseases while developing countries are stressed by occupational injuries. Steel consumption in construction industry is used as a barometer to measure the economic growth of any country. Metals production is directly associated with heat starting from raw ore handling upto the finished products. The heat produced is radiated into the ambient environment and also to the persons handling the metals. This book will provide a great help to understand the relationship of heat stress and various blood parameters in the workers of iron and steel industry.