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list produced by the American Conference of Governmental Industrial Hygienists. The one exception to this is that some of the carcinogenic polyaromadc hydrocarbons (PAHs) that were in low concentration were not singled out. Coal tar pitch volatiles were used as representative of the PAH class of chemicals. The third step was to determine if a threshold limit value ('I'LV) exisu for the chemical. The TLVs refer to airborne concentrations and represent conditions under which it is believed that nearly all workers may be repeatedly exposed eight hours a day, five days a week, without adverse health effects. TLVs are based on the best available information from industrial experience, and experimental studies on humans and animals, and when possible, all three. It should be noted that TLVs are guidelines or recommendations, not standards for determining safe or unsafe conditions. If the detected value was greater than 33~ of the TLV, it became a target chemical. Thirty-three percent of the TLV was used because the TLV is based upon a typical work week (8 hours/day, 40 hours/week) and in the case of a rite fire, exposure could be 24 hours per day. Tn cases where several types of a chemical were listed in the TLV book (e.g., nickel, nickel carbonyl, nickel sulfide), a specific chemical was selected by determining which was the most likely one to come from a fire fire and/or which had the lowest TLV. In this report, TLVs were one of several indicators used to select target chemicals. The fourth step was to compare the detected value to the subchronic (SC) and chronic (C) inhalation reference concentrations (RfC). The RfC is an estimate of the daily exposure to the human population that is likely to be without an appreciable risk of adverse effects during a portion of the lifetime (subchronic) or during the lifetime (chronic). Sensitive populations are taken into account. The RfC is based upon the No Observable Adverse Effect Level (NOAEI,) or the Lowest Observable Adverse Effect Level (LOAEL), an uncertainty factor, and a modifying factor. The RfCs are for continuous, 24 hours/day exposure, and are used as reference points for gauging the potential effects of exposures. Usually, doses that are less than the RfC ate not likely to be associated with health risks. As the frequency of exposures exceeding the RfC increases, and as the size of the excess increases, the probability increases that adverse health effects may be observed in a human population. Like the TLV, the RfC is not meant to be a standard or give a definitive statement about safe and unsafe conretttrations. However, it is appropriate to use it in this case when choosing target chemicals. The fifth step was to list the chemicals in order of decreasing value and to take the top 25% of the chemicals from each data set. If a chemical had not already been targeted as a carcinogen or one that exceeded the RfC or 33% of the TLV, a review of the chemical was conducted. The toxicity and the concentration were evaluated and a decision was made as to whether or not it should be selected as a target chemical. If no information could be found, the chemical was not included as a target chemical. It should be noted that if a range was reported in the EPA or Acurez data set, the maximum value given was the value used during the se]ection process. It should also be noted that this approach was not meant to provide an all inclusive description of the emissions from a fire fire, rather, it was used to select the most likely chemicals that are released from fire fires. As a check, the list of target chemicals was compared to actual fire fire data from a variety of 2