Quantification of the Lung Deposition Load of Smoke Particles by Plastic Type with the Lung Deposition Load Index (LDLIn)

Abstract

Many fire-related casualties are caused by smoke inhalation. The particulate matter in smoke is deposited on the walls of the respiratory system, and adversely affects the human body through the respiratory and circulatory systems. In order to estimate the adverse effects of smoke particles on the human body, it is reasonable to consider the quantity of harmful substances from smoke particles that are absorbed by each region of the respiratory tract rather than the mass concentration of smoke particles in the air. This is because the absorption amount is a consequent factor that depends on a wide variety of other factors and is not solely determined by the causative factor, that is, the mass concentration in the air. In this study, the lung deposition loads of smoke particles from plastics, such as LDPE, PA66, PMMA, and PVC were quantified using the lung deposition load index (LDLIn), and the results were compared with the findings of conventional particulate matter (PM) mass concentration indices, such as PM2.5 mass and PM10 mass. The LDLIn value was calculated from the number of smoke particles generated during a fire that were deposited in each region of the respiratory tract for the given combustion materials and fire conditions. Herein, the LDLIn quantified the lung deposition load by reflecting the surface area concentration by particle size as well as the deposition characteristics in the respiratory tract according to particle size and breathing conditions. Even at the same PM mass concentration index value, each material and fire condition resulted in different LDLIn values according to the change in concentration distribution by particle size. The LDLIn values also varied depending on the breathing conditions.