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Abstract. Emission of organic aerosol (OA) from wood combustion is not well constrained;understanding the governing factors of OA emissions would aid in explainingthe reported variability. Pyrolysis of the wood during combustion is theprocess that produces and releases OA precursors. We performed controlledpyrolysis experiments at representative combustion conditions. The conditionschanged were the temperature, wood length, wood moisture content, and woodtype. The mass loss of the wood, the particle concentrations, and light-gasconcentrations were measured continuously. The experiments were repeatable asshown by a single experiment, performed nine times, in which the real-timeparticle concentration varied by a maximum of 20 %. Highertemperatures increased the mass loss rate and the released concentration ofgases and particles. Large wood size had a lower yield of particles than thesmall size because of higher mass transfer resistance. Reactions outside thewood became important between 500 and 600 ∘C. Elevatedmoisture content reduced product formation because heat received was sharedbetween pyrolysis reactions and moisture evaporation. The thermophysicalproperties, especially the thermal diffusivity, of wood controlled thedifference in the mass loss rate and emission among seven wood types. Thiswork demonstrates that OA emission from wood pyrolysis is a deterministicprocess that depends on transport phenomena.