、、。
But Tokyo's got bad air and is too crowded to relax in.
Literal
But, Tokyo [topic-は] air [subj-が] bad [and-し], people [subj-が] too-many-[and-て] don't-settle.
だけど 'but / however' is the casual spoken conjunction. 空気が悪い '(the) air is bad' is a stock phrase for both literal air quality and figurative 'atmosphere' in a room. 多すぎて '(too many and so)' combines ~すぎる 'too much' with the te-form for causal 'and so.' 落ち着く 'to settle down / feel calm / relax' is a commonly used verb for finding emotional or physical composure.