Emissions are pollutants or substances released into the environment, most commonly referring to air emissions from vehicles, industry, power generation, and heating. Key emission types include greenhouse gases (carbon dioxide, methane, nitrous oxide) that cause climate change, and criteria air pollutants (particulate matter, nitrogen oxides, sulphur dioxide, carbon monoxide, ozone) that affect local air quality and health. Governments regulate emissions through environmental legislation: federal standards for vehicles and industrial facilities, provincial permits for major emitters, and increasingly municipal actions on buildings and transportation. Canada has committed to reducing greenhouse gas emissions under the Paris Agreement. Tracking emissions helps measure progress—Canada reports national emissions inventories, and many municipalities now track community-wide emissions as part of climate action plans. Reducing emissions requires action across transportation, buildings, industry, and electricity generation.