The term 'AIR Polluter' can be broken down into two words, 'AIR' and 'Polluter'. The word 'SOOT' is a four letter solution to the crossword puzzle. SOOT is a type of AIR pollutant that is made up of tiny particles of carbon that are released into the atmosphere from burning fossil fuels such as coal, oil, and gas. These particles can cause respiratory problems and other health issues when inhaled. SOOT is one of the main contributors to AIR pollution and can have a negative impact on the environment.