That's why he and Mayor Michael Bloomberg have asked the City Council to pass a law requiring anyone who wants to own such detectors to get a permit from the police first. And it's not just devices to detect weaponized anthrax that they want the power to control, but those that detect everything from industrial pollutants to asbestos in shoddy apartments. Want to test for pollution in low-income neighborhoods with high rates of childhood asthma? Gotta ask the cops for permission. Why? So you "will not lead to excessive false alarms and unwarranted anxiety," the first draft of the law states.

Dozens of university researchers, public-health professionals, and environmental lawyers sat in the crowd, horrified by the prospect that if this law passes, their work detecting and warning the public about airborne pollutants will become next to impossible. But [Richard] Falkenrath [NYPD's deputy commissioner for counterterrorism] pressed on, saying that unless the police can determine who gets to look for nasty stuff floating in the air, the city would be paralyzed by fear.

Objectors rightly brought up Ground Zero, where the EPA and city officials assured rescue workers the air was safe, only to retract those assurances five years and several untimely deaths and serious illnesses later.