Particulate
Particulates are very tiny pieces of a solid or liquid that are carried floating in a gas.  When the tiny pieces are solid, it is called a smoke.  When the tiny pieces are liquid, it is called an aerosol. Aerosols can be naturally found in clouds and geysers. There are also artificial aerosols such as haze and some air pollutants. Smokes can be found naturally in wildfires and volcanoes. Artificially, they can be found in cigarettes, factories and power plants. Both of them can cause air pollution and climate change. It is the job of a air filter to remove them.