Question

Which of the following air pollutants causes a reddish-brown haze in the sky?

Answer 1

I would say A. Sulfur dioxide. Local coal burning power plants have been known to change the color of the sky.

Answer 2

The pollutant being referred to above is the nitrogen dioxide. Thus, the answer is letter C. Nitrogen dioxide is a deep red - orange gas that is poisonous but is not flammable. Along with aerosols, this is responsible for the reddish brown hazes or color of the smog.