Real-time measurement of particulate matter deposition in the lung

Abstract

Air pollution and cigarette smoke are recognized health risks. A method was developed for the measurement of the deposition fraction (DF) of polydisperse particulate matter (PM) in human airways. Ten normal volunteers [three females, age range 18–67 years, mean age (SD) 43.9 (14)] made single breath exhalations after inhalation to total lung capacity. The exhaled breath was diverted to a multichannel laser diffraction chamber where the particulate profiler measured 0.3–1.0-µm particles. DF was inversely related to expiration flow-rate, 0.69 (0.02) at 4 l min⁻¹ and 0.5 (0.01) at 13 l min⁻¹, respectively (p<0.05), and was influenced by the inhalation flow-rate [0.70 (0.02) at 3 l min⁻¹ and 0.59 (0.02) at 13 l min⁻¹, respectively (p<0.05)], while no differences were found between nasal and oral inhalation (0.68 (0.05) versus 0.67 (0.06), p>0.05). Higher breath holding times were associated with elevated DF [0.74 (0.02) at 20 s, and 0.62 (0.05) without breath holding (p<0.01)]. When the expiratory flow was controlled and the breath hold time standardized, DF was reproducible (CV = 4.85%). PM can be measured in the exhaled breath and its DF can be quantified using a portable device. These methods may be useful in studies investigating the health effects of air pollution and tobacco smoke.

Keywords: :

• Particulate matter
• exhaled breath
• pollution
• lung inflammation
• particle deposition

Acknowledgements

The authors acknowledge the invaluable assistance of Dr Ivan Pozzati and Dr Edoardo Rossetti. A special thanks is extended to Dr Rinaldo Piva (FER Strumenti, Milan, Italy) for helping to set up the initial system prototype. Work was supported by the National Cancer Institute, Milan, Italy; and by the National Heart and Lung Institute, Thoracic Medicine, London, UK. No part of the research presented herein was founded by tobacco industry sources.