Emission refers to the release or discharge of something, such as gases, particles, sound waves, or electromagnetic radiation. In a more specific context, it can also refer to the act of releasing or allowing something to be released into the environment, either intentionally or unintentionally. For example, emissions from factories and power plants include pollutants such as carbon dioxide, sulfur dioxide, nitrogen oxides, and mercury that are released into the air we breathe. Emission can also refer to the act of issuing or distributing something, such as shares in a company or government bonds.