How much of the interstellar medium consists of cosmic dust?

Approximately 0.7 percent of the mass of the interstellar medium consists of solid grains, commonly referred to as cosmic dust.1

Despite this small fraction of the total mass, these dust grains play a critical role in the physical and chemical processes of the interstellar medium. They are responsible for absorbing stellar radiation, which significantly influences the temperature and ionization state of the surrounding gas. Additionally, dust grains provide the necessary surfaces for the formation of molecular hydrogen and are essential for the existence of cold, dense molecular clouds where star formation occurs.1