title: Deposition of biomass combustion aerosol particles in the human respiratory tract.
abstract: Smoke from biomass combustion has been identified as a major environmental risk factor associated with adverse health effects globally. Deposition of the smoke particles in the lungs is a crucial factor for toxicological effects, but has not previously been studied experimentally. We investigated the size-dependent respiratory-tract deposition of aerosol particles from wood combustion in humans. Two combustion conditions were studied in a wood pellet burner: efficient ("complete") combustion and low-temperature (incomplete) combustion simulating "wood smoke." The size-dependent deposition fraction of 15-to 680-nm particles was measured for 10 healthy subjects with a novel setup. Both aerosols were extensively characterized with regard to chemical and physical particle properties. The deposition was additionally estimated with the ICRP model, modified for the determined aerosol properties, in order to validate the experiments and allow a generalization of the results. The measured total deposited fraction of particles from both efficient combustion and low-temperature combustion was 0.21-0.24 by number, surface, and mass. The deposition behavior can be explained by the size distributions of the particles and by their ability to grow by water uptake in the lungs, where the relative humidity is close to saturation. The experiments were in basic agreement with the model calculations. Our findings illustrate: (1) that particles from biomass combustion obtain a size in the respiratory tract at which the deposition probability is close to its minimum, (2) that particle water absorption has substantial impact on deposition, and (3) that deposition is markedly influenced by individual factors.
authors.affiliation: Department of Physics, Lund University, Lund, Sweden. jakob.londahl@nuclear.lu.se
authors.forename: Jakob
authors.initials: J
authors.lastname: Löndahl
authors.forename: Joakim
authors.initials: J
authors.lastname: Pagels
authors.forename: Christoffer
authors.initials: C
authors.lastname: Boman
authors.forename: Erik
authors.initials: E
authors.lastname: Swietlicki
authors.forename: Andreas
authors.initials: A
authors.lastname: Massling
authors.forename: Jenny
authors.initials: J
authors.lastname: Rissler
authors.forename: Anders
authors.initials: A
authors.lastname: Blomberg
authors.forename: Mats
authors.initials: M
authors.lastname: Bohgard
authors.forename: Thomas
authors.initials: T
authors.lastname: Sandström
mesh_terms: D000328:Adult; D000336:Aerosols; D000393:Air Pollutants; D018533:Biomass; D005260:Female; D006801:Humans; D017745:Incineration; D019570:Inhalation Exposure; D008297:Male; D010316:Particle Size; D012137:Respiratory System; D012906:Smoke
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D012906:Smoke