The study, based on data from 144 children treated in Hancock County, Miss., between 2004 and 2007, said researchers aren't sure why the number of complaints increased. The data showed no difference in patterns of doctors' visits by children who lived in Federal Emergency Management Agency housing and those who did not, The Washington Post said Friday.

Health officials have previously voiced concerns about respiratory illness caused by elevated levels of formaldehyde FEMA housing.

"The issue of what, if any, effects did the hurricane -- and the changes that occurred in its aftermath -- have on the children of the Gulf Coast is one that we remain very much interested in," Ed Thompson, state health officer for Mississippi, told the newspaper.