A comparison of aerosol sampling techniques: "open" versus "closed-face" filter cassettes

Area of Science:

• Industrial Hygiene
• Occupational Health
• Environmental Science

Background:

• Standard industrial hygiene practice often employs closed-face filter cassettes for aerosol sampling.
• Concerns exist regarding potential gravimetric bias between open-face and closed-face sampling methods.
• Aerosol characteristics and sampling techniques can influence exposure assessment accuracy.

Purpose of the Study:

• To investigate gravimetric bias between open-face and closed-face aerosol sampling methods.
• To evaluate the impact of sampling technique on measured aerosol concentrations across various types.

Main Methods:

• A two-phase field study utilizing paired breathing zone samples.
• Phase I focused on industrial paint spray mist; Phase II examined wood dust, grain dust, cellulose, Portland cement, perlite, welding fumes, and chromic acid mist.
• Both open-face and closed-face 37 mm, 3-piece filter cassettes were used for sample collection.

Main Results:

• Open-face sampling consistently resulted in higher aerosol concentrations than closed-face sampling, except for cellulose dust.
• Data suggests closed-face sampling (4.0 mm inlet) may exhibit size selectivity against larger particles.
• This size selectivity could lead to underestimation of total worker aerosol exposure.

Conclusions:

• The closed-face sampling method may underestimate worker exposure to aerosols due to particle size bias.
• Industrial hygienists should consider the potential limitations of closed-face sampling for certain aerosols.
• Further research is warranted to refine aerosol sampling techniques for accurate exposure assessment.