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ASSESSMENT OF REGIONAL DEPOSITION DISTRIBUTION OF INHALED ULTRAFINE, FINE, AND COARSE PARTICLES IN HUMAN LUNGS
Impact/Purpose:
Enhancement of dose at local sites is directly related to lung injuries and may predispose eventual adverse health effects. Local dose enhancement may be a crucial factor for elevated health risk in susceptible population. Specifically, this work will support efforts to (1) Identify factors of susceptibility and describe mechanisms of health effects of acute particulate matter (PM) exposures in susceptible subgroups; (2) Describe respiratory deposition dose of ambient particles in moderate asthmatic and COPD patients; and (3) Describe comprehensive respiratory dose model based on human data for healthy adults and patients with asthma and COPD.
Description:
Deposition site and dose of inhaled particles are key determinants in health risk assessment of particulate pollutants. Previous lung deposition studies have dealt largely with total lung deposition measurement. However, particle deposition does not take place uniformly in the lung and deposition dose varies widely within the lung. The regional variation of dose is particularly prominent in lungs with obstructive airway disease, resulting incidents of extreme dose enhancement at local regions. The hypothesis of this proposed study is that enhanced local dose plays a crucial role on adverse health effects of ambient particulate matter. In the present study we have developed a novel serial bolus delivery method to assess deposition dose in small volumetric compartments of the lung in situ. Using this method, regional deposition values for ten serial lung compartments have been measured in four different subject groups including young normals, old normals (age > 60 years), asthmatics, and patients with COPD. The effects of gender was also investigated in each subject group. The experiments were performed with inert monodisperse aerosols in the size range of 0.04-5 micron in diameter and for a variety of breathing patterns mimicking sleep, resting and light exercise conditions. Results from normal young subjects have been published and data analysis is under progress for elderly and COPD subjects.