Generation and homogeneity of aerosols in a human whole-body inhalation chamber

Introduction: A 16 m(3) whole-body exposure chamber for human exposure to aerosols is described. Several modifications of the aerosol generation and distribution system were needed to ensure a stable aerosol concentration in the chamber, especially when a cyclone pre-classifier was used. Results: After these modifications, stable aerosol concentrations of aluminium oxide with a volume median diameter of 5.7 mu m, and similar to 3 mu m when the cyclone was used, could be achieved after 1 h of aerosol generation. Aerosol concentrations of 1-8 mg m(-3) generated without the cyclone could be maintained for at least 2 h after the aerosol level had stabilized. The temporal variability [coefficient of variation (CV)] of the aerosol concentration was 4-6%, while concentrations < 1 mg m(-3) showed greater relative variability. The spatial variability at 3.8 mg m(-3) without a volunteer in the chamber was 4.8%. With a volunteer in the chamber who performed 30 min of ergometric cycling during 2 h of aerosol exposure, the exposure estimated by personal sampling was 15-17% lower than monitored with an optical particle counter. The variability of personally measured exposure was higher than of stationary measurements showing CVs of 10-19%. Conclusions: These results show that controlled exposure of human volunteers to a range of concentrations can be achieved with good accuracy in this inhalation chamber. The results compare favourably with other chambers described in the literature. Personal sampling showed lower aerosol concentrations than estimated in an empty chamber and the variability was significantly higher than measured stationary.