Carbon dioxide (CO 2 ​ ), methane (CH 4 ​ ), nitrous oxide (N 2 ​ O) and ozone (O 3 ​ ) are the greenhouse gases present in Earth`s atmosphere.

Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan.