Q. I'm considering purchasing an older home in the Trenton area, and the listing indicates UFFI (Urea Formaldehyde Foam Insulation). What is UFFI, and should I be concerned? I've heard that UFFI is a health hazard.

A. Formaldehyde is a relatively inexpensive chemical which is used in many manufacturing processes. It is an acrid, colorless gas, which, at concentrations lower than 0.05 ppm, may have no detectable odor. Sources of formaldehyde in a house could be numerous, and include particle board, tobacco smoke, gas appliances, new fabrics and aerosol products. Is is also a by-product of combustion and is produced by the operation of furnaces, fireplaces and wood stoves. Formaldehyde is common in the outside air; it is found in automobile exhaust fumes and is produced by various industrial and manufacturing operations.

UFFI was a low-density foam prepared at the site, and pumped into wall cavities, where it expanded and looked and felt like shaving cream until it hardened. It is usually white or cream colored, although it was sometimes tinted blue. UUFI releases formaldehyde as it cures, and with age and degradation.

More than 100,000 Candian homes were insulated with UFFI in the 1970's, as a retrofit insulation, primarily in response to the preceived energy crisis. Better insulation meant less air exchange between the chemically laden inside and the fresh outside, which aggravated the situation. Still, incidences of fatigue, eye, nose and throat irritations were ONLY SLIGHTLY HIGHER in homes with UFFI than those without, but the fear and suspicion was enough to cause Ottawa to ban the use of the insulation.

It became known that levels of formaldehyde decrease rapidly after installation, especially in properly ventilated homes. Subsequent testing has shown that the highest levels of formaldehyde exist in homes with brand new carpeting, with or without UFFI!

Following a short curing period, the presence of UFFI does NOT affect the amount of formaldehyde in the indoor air. While not statistically significant, the homes tested were found on average to have formaldehyde levels slightly BELOW that of homes of similar ages without UFFI!

UFFI was only temporarily banned in the US, and has been used in Europe over the last 30 years, where it was never banned and is considered one of the better retrofit insulations.

CONCLUSION: No correlation has been found between formaldehyde gas and health problems, however it is difficult to draw definative conclusions concerning the exposure-response relationship for formaldehyde irritancy, due to the scarcity of information available from reliable clinical studies.

The greater concern for most enlightened buyers has been, that with the stigma attached to a "UFFI house", resale value might be affected; but the concern is quickly diminishing as recollections of "UFFI-mania" fade into history...