US President Barack Obama signed into law Sunday a bill to compensate emergency responders sickened in the rubble of the September 11 attacks, the White House said.
"We will never forget the selfless courage demonstrated by the firefighters, police officers, and first responders who risked their lives to save others," Obama said after the signing.
"I believe this is a critical step for those who continue to bear the physical scars of those attacks."
The president is currently in Hawaii, where he spent the Christmas and New Year's holidays, and was expected back in Washington on Tuesday.
The US Congress on December 22 approved a 10-year, four-billion-dollar program to help police, firefighters and other workers made ill by the fumes left in the wake of the worst terrorist attack on US soil.
The Senate and then the House of Representatives passed the measure after a last-minute compromise ended a Republican blockade in one of the final acts of the Democrat-led US Congress.
The measure offers health care and compensation to firefighters, police officers and other first responders who rushed to the scene of the World Trade Center attack in 2001.
Some of the emergency workers who survived the collapse of the Twin Towers have become sick and even died from cancer and other ailments in the nine years since, purportedly from toxic substances contained in the wreckage.
Almost 3,000 people died on September 11, 2001 when planes hijacked by Al-Qaeda suicide operatives were flown into the World Trade Center, as well as the Pentagon and a Pennsylvania field.
Another 70,000 people claim to have been exposed to the toxic fumes.