I would argue that it is not quite correct. In my opinion the LEVEL does not accelerate. (Jonathon has a more detailed explanation) The CHANGE in level accelerates. We have seen acceleration in the increase of air pollution levels

“Acceleration” means “rate of change of rate of change”. (Yes, you read that correctly.). In common parlance the word is seldom used correctly. Other than scientists, nobody ever states precisely the quantity whose acceleration is the issue. So say “in” or “of”. It doesn’t matter because everything you are likely to hear, outside of scholarly discussions, makes little sense anyway.

Yes, the sentence "We have seen acceleration in air pollution levels" is grammatically correct. It conveys that there has been an increase or quickening in the rate at which air pollution levels are rising. The difference between "acceleration in" and "acceleration of" lies in how they are used in a sentence: "Acceleration in": This phrase typically refers to the increase or quickening of something within a specific context or area. In the sentence you provided, "acceleration in air pollution levels" suggests that the acceleration is occurring within the realm of air pollution levels. In other words, it's describing how air pollution levels are accelerating. "Acceleration of": This phrase generally indicates the increase or quickening of something as a whole or in a broader sense. It doesn't necessarily specify the context or area in which the acceleration is occurring. For example, "acceleration of economic growth" means the overall increase in the pace of economic growth without specifying where it's happening. So, in your sentence, both "acceleration in air pollution levels" and "acceleration of air pollution levels" could be used depending on whether you want to emphasize where the acceleration is taking place (in the air pollution levels) or simply state that air pollution levels are accelerating as a whole.