Project Objectives For at least 5 different major classes of fuels typically involved in residual smoldering combustion (RSC) and two different moisture content conditions dispersed over at least 10 different sites. Four of these will be in the western USA, 3 in the southeast, 2 in the Lake States, and possibly 1 area in Alaska. We propose to: I. Measure the rate of release of carbon and to calculate fuel consumption and heat release incrementally over time over a time of sufficient duration (36 to 72 hours) to describe 95% of the consumption for the selected fuel elements including those of the Ottmar inventory. Included will be duff near trees, duff between trees, rotten logs larger than 6 diameter, partially rotten logs larger than 6, smaller diameter rotten logs, smaller diameter partially rotten logs, large stumps, small stumps and other fuel categories known to be important. 2. For the same fuel categories listed in item 1, measure the emissions released over time. Determine if emission factors for smoke particulate matter are lower for heavy ash conditions and whether the ash catalyzes the oxidation process with a decrease in emission factors for PM2.5, hydrocarbons, and possibly CO. Provide models for evaluating emission factors by fuel type for EPM. 3. For a few fires, using a matrix of samplers downwind of the fire, measure the local impact of smoke close to the source (within one mile), especially for those cases where drainage winds are important. 4. Provide models, guidelines, and data for describing in terms of prescription variables the probability of encountering significant RSC for different fuel situations (the fuel situations to be identified through Ottmar's photo series or survey methods). 5. Samples of several of the fuels will be returned to the Forest Fire Laboratory for further more detailed study. This part of the study will be funded by existing fire research.