The most common and most likely answer to this crossword clue is the 4 letter word SMOG
S
M
O
G
More clues leading to the result SMOG
- Gladstone's epithet's recalled in a haze
- Finally empties kitty and fumes
- Travel writing on reflection that’s bad, if inspired
- Go around on southern motorway creating air pollution
- Small cat producing air pollution
- Example of air pollution detectable in seismography
- Coming back, try starters in motorway services – pea soup?
- Some regularly flee rising pollution
- Polecat produces foul air
- Choking conditions beginning to scare cat
Buddy explains!

The straight part
We know that "pollution" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pollution = smog.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SMOG mean?
SMOG noun- A noxious mixture of particulates and gases that is the result of urban air pollution.
- To get a smog check; to check a vehicle or have it checked for emissions.