JEE Main · 2023 · 01 Feb 2023 · Shift 1 · Environmental Chemistry

Photochemical smog forms when oxides of nitrogen and unburnt hydrocarbons released by vehicles and industry react together in sunlight. The effective remedy is to cut these primary pollutants at the source, which is achieved by fitting catalytic converters that turn the nitrogen oxides and hydrocarbons into nitrogen, carbon dioxide and water before they escape. Tall chimneys merely disperse pollutants and ordinary combustion still emits nitrogen oxides, so neither tackles the cause. Photochemical smog is best controlled by using catalytic converters in automobiles and industry.