Provide answers to the following questions related to photochemical reactions, noxious pollutants and odour control. Photochemical smog has been identified as one of the primary causes of urban air pollution resulting in respiratory problems among the general population and other health effects among the more susceptible in our cities. (10) (i) Briefly explain three (3) main causes of smog and three (3) possible hard or soft engineering control methods to reduce smog production or its environmental adverse effects. For each proposed control method, provide one (1) advantage and one (1) disadvantage or challenge associated with implementing the control method. (10) (ii) Identify three (3) key causes of odorous emissions from the pretreatment area of a sewage treatment plant (e.g., screening room) or a furniture paint operation (e.g., paint and lamination furniture system). For the facility selected (only one), provide two (2) different control technologies that may reduce odorous emissions effectively at over 99%. Briefly explain what operation and maintenance issues need to be addressed to ensure consistent operation of the emission controls