Survivors of the 9/11attacks on New York will be entitled to free monitoring and treatment for about 50 types of cancer.
The decision covers 70,000 surviving emergency service workers and other survivors.
Nearly 3000 people were killed in the terror attacks on 11 September 2001, but illnesses related to the collapse of the Twin Towers after planes were flown into them have led to about 1000 more deaths since then.
Many survivors, fire fighters and police officers have argued that the toxins from the rubble gave them cancer, the BBC reports.
Until recently, the US government has insisted that there is no proof of any connection, but new evidence has caused it to change its mind.
Some 50 cancers will be added to the list of illnesses already covered by a compensation fund, such as respiratory diseases and trauma-related disorders.
For the first time, the attacks on New York and the Pentagon in Washington will be commemorated only by relatives of the victims on Tuesday, with no speeches by politicians.