The Federal Emergency Management Agency has stopped donating and selling disaster trailers while it studies reports that people living in them after hurricanes Katrina and Rita got sick from formaldehyde exposure.

Federal health scientists are in Louisiana and Mississippi investigating the safety of the travel trailers being used by hurricane victims, FEMA officials said. The scientists have been asked to identify an acceptable air quality level for formaldehyde, which is commonly used in building materials but can cause respiratory problems in high doses or with prolonged exposure.

FEMA provided about 120,000 travel trailers to victims of the 2005 hurricanes. The health review comes after some occupants last year began reporting illnesses, including nosebleeds and headaches.

Congressional leaders were outraged after documents revealed that FEMA lawyers had discouraged the agency from investigating reports that some trailers had high levels of formaldehyde.

FEMA said in a statement Wednesday that “out of an abundance of caution,” it is temporarily suspending further deployment of the travel trailers in its inventory pending the results of the formaldehyde studies, which will take into account relative humidity, the trailers’ design and how long they are lived in.

The agency recently sent about 40 of the trailers to Miami, Okla., where residents were forced out of their homes because of flooding.

Officials said FEMA may continue using other types of manufactured housing, such as mobile homes designed as long-term housing, to help disaster victims.