There are two major types of glue used for chip boards. Urea-formaldehyde glue is cheaper but less water resistant than phenol-formaldehyde glue. Both types of glue contain formaldehyde, a toxic gas. Prolonged exposure to high concentrations of formaldehyde presents a health hazard. Susceptible individuals may experience watery eyes, irritated mucus glands, nausea, and asthma symptoms. After Hurricane Katrina hit New Orleans in 2005, the Federal Emergency Management Agency provided many of the victims with trailers for temporary housing. FEMA later received criticism and negative publicity after it was discovered that many of the trailers contained unsafe levels of formaldehyde. People living in the trailers became ill. If you understand the scientific principles behind particle board outgassing, you can protect your family from a similar fate. HEATING OR WETTING the materials make symptoms worse.