Parts Per Million (ppm) Converter for Gases

Parts Per Million (ppm) Converter (lenntech.com)

The unit ppm is used in several branches in different ways. In air pollution literature ppm applied to a gas, always means parts per million by volume or by mole.

In combination with oxygen in carbon dioxide, carbon is found in the Earth's atmosphere; approximately each ppm corresponds to 2.13 Gt [gigatonnes].