The most hazardous factors of fire are smoke and toxic products of thermal decomposition. In case of fire it’s going smoke evacuation routes. During the fire the person may be at risk of disorientation and panic. Smoke is aerosol formed during thermal decomposition of materials. The object of study is timber, which is widely used in construction. Currently, the influence of wood and wood surface layer modifiers on smoke-forming ability was studied. The impact of wood surface layer modifiers on properties of aerosols remains poorly studied. Objective is to evaluate the influence of modifiers of the surface layer of wood on the formation and stability of aerosol smoke. In the work of elemental analysis method was used to assess the modifying action of selected esters of acids of phosphorus. It is known that these compounds are effective flame-retardants, and provide the biostability of wood. Granulometric analysis conducted to evaluate the properties of aerosol. It was used the method of “neutral drop” to evaluate the energy characteristics of surface modified wood. As a result of the elemental analysis the percentage of phosphorus in surface layer of wood before and after thermal decomposition was obtained. These data lead to the conclusion about high efficiency and stability of thermal effects of diethyl phosphite as a modifier. Based on granulometric analysis particulate aerosol distribution by size was obtained. Using of the selected modifiers decreases the maximum size of the aerosol particles, which reduces the optical smoke density. Esters of phosphorus acids affect the kinetic parameters of the aerosol. The greatest influence on the reduction of stability of aerosol provides diethyl phosphite. Aerosol formation, has a smaller particle size, occurs when the thermal decomposition of modified wood with thermally stable surface. Thus modifying wood by ethers of phosphorous acid reduces the propensity to smoke ability that determines the decrease of death in case of fire.