When a pollutant is removed from air by a natural process?

When a pollutant is removed from the air by a natural process, it typically involves mechanisms such as deposition, where particles settle out of the atmosphere due to gravity, or through chemical reactions that neutralize harmful substances. For instance, rain can wash pollutants from the air, a process known as washout, while vegetation can absorb certain gases through photosynthesis. These natural processes play a crucial role in maintaining air quality and reducing the concentration of harmful substances in the atmosphere.