Ultrafine Particle Deposition in Subjects with Asthma

• Published in: Environmental health perspectives Vol. 112; no. 8; pp. 879 - 882
• Main Authors: Chalupa, David C., Morrow, Paul E., Oberdörster, Günter, Utell, Mark J., Frampton, Mark W.
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.06.2004; National Institute of Environmental Health Sciences
• Subjects: Adult; Air Pollutants - pharmacokinetics; Air pollution; Asthma; Asthma - pathology; Average linear density; Breathing; Dosimetry; Female; Health benefits; Humans; Inhalation; Inhalation Exposure; Lung - chemistry; Lungs; Male; Modeling; Particle mass; Particle Size; Particle size distribution; Particulate matter; Ventilation; Ventilation systems
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.6851

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.