No. The OP is spot on in this case (though I would never question the possibility that industrial pollutants are also at play). While I forget the name of the offending tree, the BJ government planted thousands of them about 10 years ago; this helped wrt the pollution problem (fast growing and early blooming), but the white fluffy things caused so much outrage that they've been in the process of replacing them with kinder trees as fast as possible. This is precisely the reason I advise people to avoid BJ between April 20 and May 10.