There are many causes of industrial pollution, the negative byproducts of human industry. One of the main sources is the pollution caused by energy production. Byproducts produced through industry is another major component of this type of pollution. Besides pollution unique to specific sources, the release of carbon dioxide gas from various industrial sources is a key cause of global warming.
Since human beings started burning wood to stay warm, they have been releasing pollution into the environment. Not until the 18th century, though, when the Industrial Revolution began, did humans begin to have a significant effect on Earth's environment. Steam-powered factories needed an endless supply of burning wood to run. Coal and oil became the predominant source of energy as industry spread across the world. Forms of pollution became varied: radioactive waste, greenhouse gases, heavy metals and medical waste.
The first main source of industrial pollution is the production of electricity. In coal-burning power plants, fly ash is the byproduct of burned coal. Once incinerated directly into the atmosphere, most fly ash in the 21st century is either recycled or stored in vast holding ponds. This latter option, though more environmentally friendly than burning, is not without its own set of hazards. In 2008, more than a billion gallons of fly ash were released when a dike ruptured in a storage pit in Kingston, Tennessee. The rupture destroyed more than 300 acres (121 hectares) of farmland; as of the summer of 2011, litigation over the spill continues.
A more controversial form of industrial pollution formed due to energy production is nuclear waste. Spent nuclear fuel rods require proper disposal due to continued radioactivity. In the United States, spent nuclear fuel rods are stored in water baths at nuclear power plants. The water that keeps the fuel rods from melting becomes radioactive, creating more industrial waste. With the United States and other industrialized countries debating the best way to store nuclear waste, the issue remains unresolved.
Outside of energy production, all factories produce some form of pollution. Some of the most harmful to humans and the environment are heavy metals produced as a result of metal refining. Copper, mercury and lead can accumulate in animals throughout the food chain. One of the most infamous examples is Minamata disease, a neurological disorder that occurred when residents of Minamata, Japan, ate fish containing large amounts of mercury obtained from a nearby chemical factory. Since the 1950s, more than 1,700 individuals have died as a direct result of mercury poisoning.
One of the most harmful forms of industrial pollution is carbon dioxide gas released through the burning of coal and oil. Its increasing presence in Earth's atmosphere is a direct cause of global warming. Despite efforts of developed nations to reduce carbon dioxide emissions, the lax industrial regulations of developing countries have led to a continued increase in emissions.