It is grammatical, but, as R Sole said, wordy. Moreover, I doubt it says what you mean. I suspect that you want to say that you are using "visibility" in a scientific sense, that "visibility" is decreasing, and that pollution is one cause of the decrease. The proposition that "visibility" is decreasing due to pollution may be implied, but it is not explicitly stated. It requires great care to be clear and avoid verbosity when trying to express three thoughts in a single sentence. Assuming I understand what you mean, try:
"Visibility," as defined by meteorologists, has decreased annually by 1% in the city, in part because of atmospheric pollution."
That is 19 words to express those three thoughts explicitly instead of 25 words to express two thoughts explicitly and imply a third.
Of course, this will not do if that is not your intended meaning.