During the summer of 2006, the Federal Emergency Management Agency (FEMA) asked the Agency for Toxic Substances and Disease Registry (ATSDR) to analyze formaldehyde sampling data collected in 96 unoccupied trailers. The data were collected by the Environmental Protection Agency (EPA). EPA’s sampling plan was designed to answer two questions:

1. are air formaldehyde levels in closed, unventilated trailers high enough to be associated with health effects in humans;
2. and, can simple measures such as running air conditioning or opening windows lower the levels of formaldehyde?

In February 2007, ATSDR produced a health consultation containing its analysis of the formaldehyde sampling data.

ATSDR determined that the February 2007 health consultation did not sufficiently discuss the health implications of formaldehyde exposure and included language that may have been unclear, leading to potentially incorrect or inappropriate conclusions. As a result, this health consultation was prepared, and it replaces the previous health consultation.

As with the original consultation, ATSDR used data provided by FEMA from EPA’s October 2006 sampling of unoccupied trailers. ATSDR reassessed these data using rigorous statistical analytical methods and examined the data to determine whether differences existed on the basis of type of trailer or manufacturer.

This revised health consultation:

• includes background information on formaldehyde exposure and health effects
• presents data collected by EPA
• corrects the calculation errors in the February 2007 consultation
• addresses the two questions posed above
• and provides additional information about the role of other factors, such as temperature and trailer manufacturer.

ATSDR’s findings, as well as the differences between the revised health consultation and the previous version, are summarized in the executive summary of the report and discussed in detail in the body of the report.

The revised health consultation does not assess formaldehyde exposure in trailers under actual use conditions, nor does it assess the health status of people currently living in FEMA trailers. Findings cannot be generalized to all FEMA trailers and cannot predict health consequences of living in those trailers.

ATSDR and its sister agency, the Centers for Disease Control and Prevention’s (CDC’s) National Center for Environmental Health (NCEH) are continuing their work with stakeholders at the federal, state, and local levels to address health concerns related to FEMA temporary housing units. Additional information about formaldehyde and health can be found at www.cdc.gov/Features/FEMAtrailers/