Ozone is a powerful pollutant affecting lung health which occurs both indoors and outdoors. Very low levels which occur naturally are unlikely to cause any problems, but occupational exposures in a number of injuries may cause acute effects on the eyes and respiratory tract. Ozone is valued for its reactivity as an oxidising agent which means it is a powerful disinfectant. Thus it is used in many applications from aquaculture and the food industry, to wastewater treatment and the chemical industry. Ozone is also produced as a by-product by processes using ultraviolet lamps or electrical discharges (i.e. ionisation).