The Open Dictionary

photochemical smog

noun

UK/ˌfəʊ.təʊ.kem.ɪ.kᵊl ˈsmɒɡ/
US/ˌfoʊ.t̬oʊ.kem.ɪ.kᵊl ˈsmɑːɡ/

Definitions of photochemical smog noun

  1. CountableUncountable

    a type of air pollution caused by the reaction of sunlight with chemicals released from vehicles and industrial sources.

    • Photochemical smog is particularly severe over the city during the summer months.

    • The region's photochemical smog problem is worsening due to increased vehicle emissions.

    • Factory emissions are one of the primary contributors to the formation of photochemical smog.