Question

which gas has caused photo chemical smog

Answer 1

nitrogen oxides

nitrogen oxidesPhotochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight.

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Answer 2

Answer:

Nitrogen oxides emissions, or NOx (NO + NO2), are of major importance in the generation of ozone through photochemical reactions with reactive hydrocarbons. Ozone is the principle contributor to photochemical smog and is toxic to humans.