Identification and analysis of ambient EMPs.

Mineral particles have long been observed in the ambient air and for >40 years, samples of these airborne particulate have been collected in attempt to identify and quantify the amount of asbestos particles in the air. For most of this time, regulated asbestos particles (in the shape of fibers) were the target for these analyses. However, since the turn of the century, more emphasis has been placed on finding and identifying elongate mineral particles (EMPs). For EMPs (particularly serpentine and amphibole minerals), these airborne particles have generally been associated with industrial activities and were reported as "asbestos". Recent monitoring around construction activities involving earth moving have reported concentrations of different mineral particles at sites of varying distance from the activity. The location of detected ambient elongate mineral particles (EMPs) is similar to the locations of soils that also contain EMPs. This close association indicates the necessity for proper mineral identification and valid morphological characterization to allow for source identification. Unfortunately, there continues to be problems with mineral identifications in many studies, regardless of the morphological habit of the particle. This paper addresses the issue of proper mineral identification in ambient air samples.