Answer:
It exists in damp, cold weather.
Step-by-step explanation:
Sulfurous smog is a type of air pollution that is caused by the burning of sulfur-containing fuels, such as coal and oil.
Sulfurous smog is most common in damp, cold weather because the moisture in the air helps to condense the sulfur dioxide and other pollutants into tiny droplets. These droplets can then be easily inhaled, causing respiratory problems.
Therefore, the answer is it exists in damp, cold weather.

The other statements are not true about sulfurous smog.
- Unburned hydrocarbons are a major component of photochemical smog, not sulfurous smog.
- It does not create a brown haze in the air. Sulfurous smog typically creates a yellowish-brown haze.
- Nitrogen oxides are also a component of photochemical smog, but not sulfurous smog.