Heavy metals, especially Cd, Hg and Pb, have become an important environmental problem because of their toxicity. One such example is the accumulation of cadmium in kidney and liver (Lee, 1972). Many metals can be hazardous to forest soil and aquatic ecosystems. Tyler (1984) has noticed that mosses and lichens may be killed by Cu and Zn. Heavy metals can also work as catalysts in atmospheric reactions, for example in acid formation (Freiberg and Schwartz, 1981). It is a characteristic of most heavy metals that they volatilize easily during high- temperature combustion processes. Metals will condense on small particle surfaces in the cooler regions of a furnace. Because of condensation and surface reactions, volatile metals will be enriched in the submicron particles of flue gases (Haynes et al., 1982; McMurry and Wilson, 1982). A component of the metals will also appear as vapor. Consequently it is difficult to take representative samples of heavy metals from the gases, because gaseous metals will penetrate the most commonly used sampling devices such as filter, impactor, cyclone and impinger bottles (SCby et al. 1980). A sampler to collect gaseous metals and to fractionate the particles into three size classes has been developed. The sampler is based on vaporization/condensation principles.