On February 10, 2009, New York Mayor Michael Bloomberg signed
legislation reducing the amount of time that vehicles can idle near
schools and expanding New York City's enforcement of idling laws. Introductory Number 631-A
reduces the amount of time that non-emergency vehicles can idle
adjacent to schools from three minutes to one minute. In addition, the
legislation requires the Environmental Control Board and Department of FinanceIntroductory Number 40-A authorizes the Department of Parks and Recreation and the Department of Sanitation to enforce idling laws (enforcement was previously limited to the Department of Environmental Protection
and the Police Department). The new legislation also gives civilians
the ability to report truck idling violations. (Previously, citizens
were entitled to report noncompliant buses only.) Hearings were
recently held on a third piece of potential legislation, known as Proposed Introductory Number 881-A,
which, if passed would require the city to implement technology to
allow traffic enforcement agents to issue idling tickets via their
hand-held computers.
to submit annual reports on the number of idling violations issued and the total value of penalties assessed.

Here is a transcription of the anti-idling law from webdocs.nyccouncil. And you can see the names of the council members who wrote it. I see that de Blasio had a part in it.

Int. No. 631-A

By Council Members Liu, Arroyo, Jackson, Brewer, Dickens,
Gerson, Gonzalez, James, Koppell, Martinez, Palma, Reyna, Sanders Jr., Foster,
Mark-Viverito, Mendez, de Blasio, White Jr., Vann, Garodnick, Gennaro, Rivera, Sears and Stewart

..Title

A Local Law to amend the administrative code of the city of New York, in relation to
engine idling.

..Body

Be it enacted by the Council as follows:

Section 1. Subdivision a of section 24-163 of subchapter seven of chapter
one of title 24 of the administrative code of the city of New York is amended to read as follows:

§24-163 Operation of motor vehicle; idling of engine
restricted.  (a)  No person shall cause or permit the engine of
a motor vehicle, other than a legally authorized emergency motor vehicle, to
idle for longer than three minutes, except as provided in subdivision (f) of
this section, while parking as defined in section one hundred twenty-nine
of the vehicle and traffic law, standing as defined in section one hundred
forty-five of the vehicle and traffic law, or stopping as defined in section
one hundred forty-seven of the vehicle and traffic law, unless the engine is
used to operate a loading, unloading or processing device.  When the ambient temperature is in excess of
forty degrees Fahrenheit, no person shall cause or permit the engine of a bus
as defined in section one hundred four of the vehicle and traffic law to idle
while parking, standing, or stopping (as defined above) at any terminal point,
whether or not enclosed, along an established route….read more here