Particle board is made from small softwood particles that resemble coarse sawdust, and is usually held together with potent urea-formaldehyde (UF) glue. Particle board is frequently used as an underlayment for carpeting and is one of the chief causes of high formaldehyde concentrations in mobile homes. 

Research has shown particle board products made with UF glue are among the most common and worst offenders for offgassing formaldehyde into the indoor air. One study found that children living in houses containing a significant amount of particle board were more likely to develop headaches, wheezy bronchitis and eye and nose irritation.

Wall paneling, furniture, kitchen and bath cabinets are often made with particle board. Normally these materials are covered with a thin veneer of an attractive hardwood. Unfortunately, the veneer does little to block the formaldehyde emissions.

Some companies substitute isocyanate glues for UF glues in the manufacture of particle board. While isocyanates are quite dangerous during the manufacturing process, they outgas very quickly. Materials made with isocyanate glue are inert by the time they get to the marketplace.

Formaldehyde-free particle board is now available. Produced with natural materials such as wheat or straw and isocyanate glues, these products eliminate risks associated with the offgassing of formaldehyde from conventional particle board.