Comparison of inspirable airborne particle size selective sampling and respiratory tract penetration

Both the Environmental Protection Agency (EPA) and the American Conference of Governmental Industrial Hygienists (ACGIH) are proposing a thoracic sampler to collect airborne particles indicative of those that may be presented to the lung during normal respiration through the mouth, based upon a ten micrometer aerodynamic diameter cut-size. Earlier standards for respiratory samplers (Atomic Energy Commission [AEC] and ACGIH) emphasized deep lung pulmonary penetration of particles during respiration via the nose. We have quantitatively compared these types of samplers and found the thoracic sampler to slightly overemphasize the importance of larger particles (larger than ten micrometer aerodynamic diameter) even for mouth breathing and the traditional respirable dust sampler to slightly overemphasize intermediate particles (larger than two micrometer aerodynamic diameter) for nose breathing while underestimating the exposure during mouth breathing. These sample types are recommended for use in conjunction with total mass sampling to yield information on potential risk to lung as well as upper respiratory tract deposition