In this Jan. 8, 2001 file photo, a rescue worker wearing a dust mask, peers through a cloud of dust created by an excavator at the World Trade Center site in New York. A decade’s worth of study has answered only a handful of questions about the hundreds of health conditions believed to be related to the tons of gray dust that fell on the city when the trade center collapsed, from post-traumatic stress disorder, asthma and respiratory illness to vitamin deficiencies, strange rashes and cancer. (AP Photo/Mark Lennihan)

Associated Press
In this Jan. 8, 2001 file photo, a rescue worker wearing a dust mask, peers through a cloud of dust created by an excavator at the World Trade Center site in New York. A decade’s worth of study has answered only a handful of questions about the hundreds of health conditions believed to be related to the tons of gray dust that fell on the city when the trade center collapsed, from post-traumatic stress disorder, asthma and respiratory illness to vitamin deficiencies, strange rashes and cancer. (AP Photo/Mark Lennihan)
In this Jan. 8, 2001 file photo, a rescue worker wearing a dust mask, peers through a cloud of dust created by an excavator at the World Trade Center site in New York. A decade’s worth of study has answered only a handful of questions about the hundreds of health conditions believed to be related to the tons of gray dust that fell on the city when the trade center collapsed, from post-traumatic stress disorder, asthma and respiratory illness to vitamin deficiencies, strange rashes and cancer. (AP Photo/Mark Lennihan)
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