By composition, Earth’s atmosphere is made up of nitrogen gas (78%), oxygen gas (21%), and other trace gases (such as argon and carbon dioxide). This balance is essential to all life here on Earth, so the introduction of pollutants can have a profound and damaging effect. All told, pollution can take many forms, like carbon compounds such as carbon monoxide (CO) and carbon dioxide (CO²). sulfuric compounds like sulfur dioxide (SO²), methane, radioactive decay, or toxic chemicals.