Answer:
Temperature inversions
Step-by-step explanation:
Temperature inversions can act as a lid or trap, thus worsening air-pollution problems.
Temperature inversion is an increase in air temperature as it rises with respect to ground height. As the temperature inversion rises, so does the air density. Toxic and bad pollutants can occur in this area itself.
Since the temperature inversion is stable and windless it will remain at one particular height collected with all the negative substances. This is further referred to polluted air and often occurs in large, heavily populated cities.