While preparing to build a hydroelectric dam, the safety for various potential hazards must be given attention. Some of these include special attention towards the channels leading to dangerous areas or spillways, attention towards the effectiveness of the barriers, areas where higher currents exist, attention must also be given towards environmental aspects such as damming the rivers impacts wild and aquatic life, reduction of dissolved oxygen harming the fishes, and also while building the dam the communities living around should be taken into consideration that there is no potential hazard to them.
Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.
