During the first week of April, 1991 the Wisconsin Department of Natural Resources (WDNR) conducted a series of air emissions tests of a small industrial wood-fired boiler in northern Wisconsin. The boiler was firing a virgin hogged wood/wood waste fuel with a moisture content of about 35 percent The pollutants measured were particulates, nitrogen oxides (NOx), carbon monoxide (CO), total hydrocarbons (THC), benzene, formaldehyde (CHOH), polycydic organic matter (POM, eg. benzo (a) pyrene), aldehydes, and trace metals (As, Ba, Cu, Pb, Mn, Ni, K. Se, Na, and Zn)