| Ultrafine Particle Deposition in Subjects with Asthma David C. Chalupa,1 Paul E. Morrow,2 Günter Oberdörster,2 Mark J. Utell,1,2 and Mark W. Frampton1,2 Departments of 1Medicine and 2Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Abstract
Ambient air particles in the ultrafine size range (diameter < 100 nm) may contribute to the health effects of particulate matter. However, there are few data on ultrafine particle deposition during spontaneous breathing, and none in people with asthma. Sixteen subjects with mild to moderate asthma were exposed for 2 hr, by mouthpiece, to ultrafine carbon particles with a count median diameter (CMD) of 23 nm and a geometric standard deviation of 1.6. Deposition was measured during spontaneous breathing at rest (minute ventilation, 13.3 ± 2.0 L/min) and exercise (minute ventilation, 41.9 ± 9.0 L/min) . The mean ± SD fractional deposition was 0.76 ± 0.05 by particle number and 0.69 ± 0.07 by particle mass concentration. The number deposition fraction increased as particle size decreased, reaching 0.84 ± 0.03 for the smallest particles (midpoint CMD = 8.7 nm) . No differences between sexes were observed. The deposition fraction increased during exercise to 0.86 ± 0.04 and 0.79 ± 0.05 by particle number and mass concentration, respectively, and reached 0.93 ± 0.02 for the smallest particles. Experimental deposition data exceeded model predictions during exercise. The deposition at rest was greater in these subjects with asthma than in previously studied healthy subjects (0.76 ± 0.05 vs. 0.65 ± 0.10, p < 0.001) . The efficient respiratory deposition of ultrafine particles increases further in subjects with asthma. Key words: air pollution, asthma, deposition, dosimetry, inhalation, ultrafine particles. Environ Health Perspect 112:879-882 (2004) . doi:10.1289/ehp.6851 available via http://dx.doi.org/ [Online 2 March 2004]
Address correspondence to M.W. Frampton, University of Rochester School of Medicine, 601 Elmwood Ave., Box 692, Rochester, NY 14642-8692 USA. Telephone: (585) 275-4861. Fax: (585) 273-1114. E-mail: mark_frampton@urmc.rochester.edu This work was supported by National Institutes of Health grants RO1 ES011853, P30 ESO01247, and RR00044 ; U.S. Environmental Protection Agency (EPA) assistance agreement R827354-01 ; Electric Power Research Institute grant WO6325-01 ; and Health Effects Institute (HEI) contract 98-19. Research described in this article was conducted under contract to the HEI, an organization jointly funded by the U.S. EPA (assistance agreement X-812059) and automotive manufacturers. The contents of this article do not necessarily reflect the views of the HEI, nor do they necessarily reflect the policies of the U.S. EPA or of automotive manufacturers. The authors declare they have no competing financial interests. Received 10 November 2003 ; accepted 2 March 2004.
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