The James Zadroga 9/11 Health and Compensation Act has taken effect.
Mayor Michael Bloomberg joined U.S. Health and Human Services Secretary Kathleen Sebelius and other officials Friday at Mount Sinai Medical Center in New York.
Bloomberg says the law guarantees that those facing health problems related to 9/11 will be monitored by doctors and receive treatment at least until 2015.
He says the federal government is sharing in the responsibility for providing care to first-responders and others injured by the toxic dust at ground zero.
The law, passed in December, also reopened a victims' compensation fund for another five years. It covers wage and other economic losses of sickened workers and residents.
The legislation is named for a police detective who died at age 34 after working at ground zero.