%0 Journal Article
%T The Effect of Ventilation, Age, and Asthmatic Condition on Ultrafine Particle Deposition in Children
%A Hector A. Olvera
%A Daniel Perez
%A Juan W. Clague
%A Yung-Sung Cheng
%A Wen-Whai Li
%A Maria A. Amaya
%A Scott W. Burchiel
%A Marianne Berwick
%A Nicholas E. Pingitore
%J Pulmonary Medicine
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/736290
%X Ultrafine particles (UFPs) contribute to health risks associated with air pollution, especially respiratory disease in children. Nonetheless, experimental data on UFP deposition in asthmatic children has been minimal. In this study, the effect of ventilation, developing respiratory physiology, and asthmatic condition on the deposition efficiency of ultrafine particles in children was explored. Deposited fractions of UFP (10每200ˋnm) were determined in 9 asthmatic children, 8 nonasthmatic children, and 5 nonasthmatic adults. Deposition efficiencies in adults served as reference of fully developed respiratory physiologies. A validated deposition model was employed as an auxiliary tool to assess the independent effect of varying ventilation on deposition. Asthmatic conditions were confirmed via pre-and post-bronchodilator spirometry. Subjects were exposed to a hygroscopic aerosol with number geometric mean diameter of 27每31ˋnm, geometric standard deviation of 1.8每2.0, and concentration of particles cmˋ3. Exposure was through a silicone mouthpiece. Total deposited fraction (TDF) and normalized deposition rate were 50% and 32% higher in children than in adults. Accounting for tidal volume and age variation, TDF was 21% higher in asthmatic than in non-asthmatic children. The higher health risks of air pollution exposure observed in children and asthmatics might be augmented by their susceptibility to higher dosages of UFP. 1. Introduction Particles smaller than 100ˋnm, due to their size, can elude human defense mechanisms, penetrate deep into the body, reach the bloodstream, and accumulate in sensitive target sites such as bone marrow, lymph nodes, spleen, heart, brain, and the central nervous system [1每9]. The distinctive translocation properties of nanoparticles have prompted their application as drug carrying vectors and in early detection, diagnosis, and treatment of diseases [7, 10每19]. Unfortunately, such translocation properties might also explain why ultrafine particles (UFP) significantly contribute to the elevated health risks associated with urban air pollution [3, 20每22]. In particular, UFPs have been shown to impact the cardiovascular, pulmonary, and central nervous systems, especially in children, the elderly, and those with respiratory diseases [5, 20每26]. Exposure to UFPs has also been linked to pulmonary inflammation and increased susceptibility to respiratory infections as well as increased risk of cancer, chronic obstructive pulmonary diseases, and exacerbation of asthma [27每38]. Despite extensive research on the health effects of air
%U http://www.hindawi.com/journals/pm/2012/736290/