smog-forming

The term 'smog-forming' is a modern English compound adjective. Its first element, 'smog', is a 20th-century portmanteau coined in London to describe the city's characteristic polluted fog, a blend of industrial 'smoke' and natural 'fog'. The second element, 'forming', derives from the Latin 'formare' (to shape), via Old French, retaining its core sense of causing something to come into existence. When combined, the term logically and transparently describes pollutants (like nitrogen oxides) that participate in the photochemical reactions which 'form' or create the atmospheric haze known as 'smog'.

Structure: smog (smog) + forming (making) - smog: A blend word (Portmanteau) of English origin, combining 'smoke' and 'fog'. It functions as the core noun element. - forming: Of English origin, from the verb 'form' (to make, shape) plus the present participle suffix '-ing'. It functions as an adjectival element meaning "that makes or creates".