This is a colourless gas with a sharp offensive odour. It can be manmade or produced naturally and dissolves easily in water. It is made up of 1 nitrogen and 3 hydrogen atoms and is very alkaline in water based solutions. It is found in many household cleaners and chloramines; now used extensively in town water treatment in Australia and throughout the world. It is irritating to the skin, eyes, nose, throat and lungs. Levels in drinking water should not exceed 0.5 mg/L.