Residents of FEMA trailers who want their units tested for formaldehyde will have that opportunity. The Federal Emergency Management Agency, in a news release Friday, said it would open up the testing program to those living in federally supplied trailers and mobile homes along the Gulf Coast, and also those in federally declared disaster areas in Arkansas, California, Florida, Kansas, New Mexico, New York, Minnesota, Missouri, Oklahoma and Pennsylvania.

Earlier this month, the Centers for Disease Control and Prevention said fumes from 519 tested trailers and mobile homes in Louisiana and Mississippi were, on average, about five times what people are exposed to in most modern homes.

Formaldehyde is a preservative commonly used in construction materials; it can lead to breathing problems and is also believed to cause cancer.

FEMA said testing could begin as early as this coming week and would begin with residents on the Gulf Coast who have already requested testing.

About 200 trailers and mobile homes would be tested each week, FEMA said. The contract to do the testing went to Bureau Veritas, which also did the recent testing of the 519 units, according to FEMA.

Since FEMA and the CDC announced the early testing results, FEMA said Friday its formaldehyde hotline had logged more than 1,900 calls from along the Gulf Coast and that 334 of those requested testing.

Households had been offered immediate moves to a hotel or motel, and 285 had accepted that, FEMA said Friday. Eighty-two others had moved into alternative long-term housing, 133 had refused all options and the rest were weighing their options, FEMA said.