If that were the case, then everyone who lived/worked near Ground Zero in the months before 9/11 would have had these same health consequences.

Instead, it's clear that that isn't the case. Plenty of research, including studies on firefighters and other first responders on 9/11 and the days after (and plenty of anecdata from doctors around here) have borne out that the health effects from being around Ground Zero for the first couple of weeks after 9/11 was much deadlier than simply breathing in mild air pollution.

(In addition, while I didn't live here at the turn of the century... what air pollution? Manhattan doesn't have a collection of coal power plants near Wall Street. It doesn't have more ICE cars than most other cities; it probably had fewer ICE cars per square mile than an ordinary Wal-mart parking lot in the suburbs.)