Aerosol
![Mist and clouds are aerosols.](/Images/godic/202412/17/Heavy_mist2412.jpg")
![Because dust particles mostly settle to the ground, this visible dust is a suspension, not an aerosol. Very fine dust, common in the Sahara Desert, however, can constitute an aerosol as it travels on the winds for weeks.](/Images/godic/202412/17/DustWorkerStreet32412.jpg")
![Photomicrograph made with a Scanning Electron Microscope (SEM): Fly ash particles at 2,000x magnification. Most of the particles in this aerosol are nearly spherical.](/Images/godic/202412/17/Fly_Ash_FHWA_dot_gov2412.jpg")
![The same hypothetical log-normal aerosol distribution plotted, from top to bottom, as a number vs. diameter distribution, a surface area vs. diameter distribution, and a volume vs. diameter distribution. Typical mode names are shows at the top. Each distribution is normalized so that the total area is 1000.](/Images/godic/202412/17/Synthetic_aerosol_distribution_in_number_area_and_volume_space2412.png")
An aerosol is a colloid of fine solid particles or liquid droplets, in air or another gas. Aerosols can be natural or artificial. Examples of natural aerosols are fog, forest exudates and geyser steam. Examples of artificial aerosols are haze, dust, particulate air pollutants and smoke. The liquid or solid particles have diameter mostly smaller than 1 μm or so; larger particles with a significant settling speed make the mixture a suspension, but the distinction is not clear-cut. In general conversation, aerosol usually refers to an aerosol spray that delivers a consumer product from a can or similar container. Other technological applications of aerosols include dispersal of pesticides, medical treatment of respiratory illnesses, and combustion technology. Diseases can also spread by means of small droplets in the breath, also called aerosols.