The Centers for Disease Control released Wednesday a study, stating that plywood and particleboards have been the main reasons for the massive amounts of formaldehyde emissions in the FEMA trailers that have been used to temporarily house the victims of the Katrina hurricane.

Formaldehyde is a toxic component that is usually found in construction materials, mainly in those based on wood. Previous medical studies have shown that the substance causes or worsens respiratory problems if a person is exposed to a large enough quantity of it. Doctors have also reasons to believe that formaldehyde might be a factor influencing the development of nasal cancer.

The study made by the CDC measured the formaldehyde emission levels in the walls, floors, ceilings and other parts of the trailers where wood was known to have been used. It found that even though each material presented a level of emissions that complied with the standards set for the industry, the total amount of it was four to eleven times higher than that in normal homes.

These results prompted experts to think that the reason for what happened lies in improper use of materials, as well as the poor ventilation conditions of the trailers, whose volume is far smaller than that of normal homes, and is more likely to present a higher concentration of toxic chemicals.

FEMA has declared that it has already taken into account the study and that the new trailers that are being used for the Iowa victims of the recent flooding are built using less wood and are tested for formaldehyde as well as other volatile toxic substances.