Evaluation of physical sampling efficiency for cyclone-based personal bioaerosol samplers in moving air environments

Abstract

The need to determine occupational exposure to bioaerosols has notably increased in the past decade, especially for microbiology-related workplaces and laboratories. Recently, two new cyclone-based personal bioaerosol samplers were developed by the National Institute for Occupational Safety and Health (NIOSH) in the USA and the Research Center for Toxicology and Hygienic Regulation of Biopreparations (RCT & HRB) in Russia to monitor bioaerosol exposure in the workplace. Here, a series of wind tunnel experiments were carried out to evaluate the physical sampling performance of these two samplers in moving air conditions, which could provide information for personal biological monitoring in a moving air environment. The experiments were conducted in a small wind tunnel facility using three wind speeds (0.5, 1.0 and 2.0 m s(-1)) and three sampling orientations (0°, 90°, and 180°) with respect to the wind direction. Monodispersed particles ranging from 0.5 to 10 μm were employed as the test aerosols. The evaluation of the physical sampling performance was focused on the aspiration efficiency and capture efficiency of the two samplers. The test results showed that the orientation-averaged aspiration efficiencies of the two samplers closely agreed with the American Conference of Governmental Industrial Hygienists (ACGIH) inhalable convention within the particle sizes used in the evaluation tests, and the effect of the wind speed on the aspiration efficiency was found negligible. The capture efficiencies of these two samplers ranged from 70% to 80%. These data offer important information on the insight into the physical sampling characteristics of the two test samplers.

Fig. 1

Schematic diagram of the test personal bioaerosol samplers: (a) NIOSH BC and (b) RCT & HRB PAS-5.

Fig. 2

The small wind tunnel facility at Lovelace Respiratory Research Institute (showing individually labeled components).

Fig. 3

Test aerosol generation system.

Fig. 4

Experimental setup of the test sampler and isokinetic probe in the wind tunnel test chamber.

Fig. 5

The orientation-averaged aspiration efficiency as a function of the aerodynamic diameter for the two test personal bioaerosol samplers and the reference sampler, (a) U = 0.5 m s⁻¹, (b) U = 1.0 m s⁻¹, and (c) U = 2.0 m s⁻¹ (error bars represent the standard deviation of the experiments).

Fig. 6

The aspiration efficiency as a function of the aerodynamic diameter in different sampling orientations for the test personal bioaerosol samplers and the reference sampler shown in (a) BC, (b) PAS-5, and (c) IOM.

Fig. 7

The capture efficiency, filter collection, and wall deposition of the test samplers at different wind speeds: U = 0.5 m s⁻¹, U = 1.0 m s⁻¹, and U = 2.0 m s⁻¹ (L: Liquid; F: Filter; W: Wall; L + W: Liquid + Wall; and error bars represent the standard deviation of the experiments.