Sen. Hillary Clinton and Rep. Jerrold Nadler said in a statement that they will "conduct companion hearings into the failures of the federal government in responding to the environmental crisis that resulted" from the buildings' collapse, which spewed hundreds of tons of potentially toxic dust into the air of lower Manhattan.

Clinton is chair of the Senate Environment and Public Works Subcommittee on Superfund and Environmental Health, while Nadler chairs the House Judiciary Subcommittee on the Constitution, Civil Rights and Civil Liberties.

The two said they planned to probe "the administration's misleading public statements about post-Sept. 11 air quality, as well as its continued failure to provide a proper testing and cleaning of indoor spaces contaminated by (World Trade Center) toxins and its lack of provision of health care for the thousands of people who are ill as a result of exposure to the pollutants."

"We need to examine what went wrong and assess whether the federal government is better prepared to respond to environmental hazards in future disasters," said Clinton.

"Finally, we have an opportunity to hear, on the record and first hand, who in the federal government was really responsible for key decisions about the handling of post-Sept. 11 air quality ... decisions that are still having an impact on 9/11 victims today," said Nadler.

As many as 70 percent of 10,000 workers who worked on the cleanup at the center and were subsequently screened at the Mount Sinai hospital in New York City suffered from breathing difficulties, and more than 2,000 city firefighters have been treated for serious respiratory illness, according to the New York Times.