[Airway deposition of nanoparticles from second hand cigarette smoke]

Abstract

Introduction: Second hand cigarette smoke consists predominantly of nanoparticles (with two dimensions less than 100 nanometres). The aim of this study was to examine the aerosol of cigarette smoke suspended in the air of a smoking room, its disappearance over the course of time, and its retention in the airways of passive smokers, as these processes remain poorly characterised.

Methods: A smoking machine produced cigarette smoke in a room. A low pressure electrostatic impactor with 13 plates, measured the size distribution and the concentration of the smallest particle sizes in the room air. Healthy adult volunteers (n=14) inhaled and exhaled this air through a nasal mask, allowing calculation of the retention of nanometric particles.

Results: The tobacco smoke aerosol was composed of 75% of nanometric particles. The half-life of these particles in the air was 18min. After 2h, 3% of the tobacco smoke particles remained suspended in the air. In passive smokers, the measured airway retention was on average 20%.

Conclusion: This work shows that 75% of second hand cigarette smoke aerosol is made up of nanoparticles. When non-smokers inhale this passively, 20% of the particles are retained in their respiratory tract.