The Federal Emergency Management Agency has postponed plans to test the air quality in trailers occupied by hurricane victims.

Last Friday, scientists from the Centers for Disease Control and Prevention in Atlanta were scheduled to begin testing FEMA trailers in Mississippi for levels of formaldehyde, a carcinogen that can cause respiratory problems.

However, the tests were postponed indefinitely at FEMA’s request, before they started. The agency wants to “finalize the testing process” and identify “action levels for responding to the results” before the tests are conducted, FEMA spokeswoman Mary Margaret Walker said Tuesday.

“I don’t think we want to do a test without knowing what we’re going to do with the results,” Walker said.

FEMA ordered the tests and is funding them, said CDC spokesman Charles Green.

“It’s their money,” Green said. “If they tell us to stop, we have to stop.”

Hundreds of Gulf Coast families have asked FEMA to move them out of trailers amid concerns that the units are exposing them to hazardous levels of formaldehyde.

The CDC planned to test at least 300 trailers in Mississippi and Louisiana whose occupants volunteered for the study.

“We had to call folks back and cancel,” Green said.

It’s not clear when testing now will start.

“We certainly hope and expect that it will not be much of a delay,” Walker said Tuesday.

CDC scientists developed protocols for conducting the air quality tests. Walker, however, said there aren’t any “commonly accepted” standards for determining safe levels of formaldehyde in FEMA trailers.

“It’s all about giving concrete and good information to the people who are living in these units and have been for two years,” Walker added.

FEMA has temporarily suspended the sale of its used trailers. The agency also says it won’t be using the units as temporary shelters for victims of future disasters until the safety concerns are resolved.

Thousands of families are still living in FEMA trailers more than two years after hurricanes Katrina and Rita hit the Gulf Coast.

A total of 10,789 travel trailers in Mississippi and 37,530 in Louisiana are still occupied by storm victims. More than 3,000 families in both states have asked FEMA to move them out of trailers and into apartments, hotel rooms or other forms of temporary housing.

In the meantime, hundreds of Gulf Coast residents are suing trailer manufacturers for allegedly providing FEMA with poorly constructed units that may have jeopardized their health.