Dust and rust. Not a phenomenon
The phenomenon where coins gradually become dirty is called tarnishing. Tarnishing occurs when the metal surface of the coins reacts with elements in the environment, such as oxygen or sulfur, causing discoloration and buildup of grime.
dirty
Some guy call Herbert was dirty.
A t
Call him papi(;
there is lot of dirt and flies in the dirty city which is destroying the health of people as well as the beauty of the city so it is appropriate to call dirty city festering
Silence
Dirty bolloks
Dirty Dancing
Depends what you call dirty. Some cultures consider pork dirty, but I eat it frequently.
This phenomenon is called smog, which is a combination of smoke and fog. Smog is a type of air pollution that occurs when pollutants react with sunlight and moisture in the atmosphere, creating a visible haze.
A macro-climate.