Factories throughout the world that want to help stop pollution have two basic options: working to control existing pollution and trying to prevent future pollution. In many countries, factories are obligated to abide by certain environmental laws; others must implement their own self-imposed methods to stop pollution. Usually, their goals are to minimize the damage done by existing pollutants and to attempt to prevent further pollution by modifying their industrial practices. A related option is to sell specific by-products as raw materials to other industries.
Air pollution usually takes the form of smoke or smog, but sometimes the pollutants are invisible to the naked eye. Contaminants can include particles in the air, as well as solid and liquid aerosols; other common air pollutants include sulfur oxides, hydrocarbons, and carbon monoxide, which are produced by industrial activities such as burning coal. To help stop pollution, a factory can modify its procedures or use different equipment. For example, filters on smokestacks can help stop pollution by catching harmful substances and cleaning fumes before they reach the air. In addition, a factory might reduce carbon monoxide emissions, for instance, by burning natural gas instead of oil or coal.
Water pollution harms animals and plants that live in rivers, streams, and oceans. Factories can help stop pollution by treating sewage and other waste before releasing it into the environment. Furthermore, water treatment plants clean polluted water and add chemicals in order to make it considered safe for wildlife and, often, for human use. In the U.S. and abroad, dumping hazardous materials into ocean water is prohibited by international regulations. The U.S. is also one of many countries subject to federal legislation that mandates specific anti-pollution practices.
In addition to modifying their industrial practices, many factories try to stop pollution by selling certain pollutants as by-products. Rather than being dumped, the by-products are recycled or reused as raw materials for another product. A recently documented example demonstrates the conversion of "slag," a steel-making by-product, into a useful raw material for making cement. The most notable environmental benefit of these sales was a reduction in greenhouse gas emissions.
While these efforts to stop pollution might have alleviated some problems, they have not eliminated them. Climate change, for instance, continues to be a concern for all countries, and it is often unclear whether certain anti-pollution measures have been effective. In many industrialized countries, the ultimate goal is to prevent pollution altogether, rather than having to manage it.