Abstract View
Comparison of Bystander Asbestos Exposure Data to Fiber Migration Assumptions
STEVEN COMPTON, MVA Scientific Consultants
Abstract Number: 604
Working Group: Aerosol Physics
Abstract
When work involving asbestos or asbestos-containing materials results in the release of airborne asbestos fibers, both the asbestos worker and any bystanders in that area are at an increased risk of exposure to asbestos. Quantifying the exposure to bystanders is accomplished by collecting an air sample during the activity in question in the personal breathing zone (PBZ) of the bystander. Alternatively, a stationary (area) air sample can be collected some set distance from the activity as a proxy for a breathing zone sample.
If no bystander air sample data is available, then one may attempt to estimate what the exposure would have been from applying air flow models to exposure data for the asbestos worker. Individual airborne asbestos fiber sizes can be nanometers in diameter, whereas bundles can reach the millimeter range. This means the mechanics of particle migration after release can range from advective to practically newtonian. However, the widths of fibers collected in an air sample typically do not exceed the micrometer range, so a complex fluid dynamics model is best suited to approximate fiber migration. One such model was proposed by Donovan et al. in 2011.
Simulations of asbestos release from a variety of work practices performed in controlled conditions were conducted over a time span of several decades. The intent of each simulation was to investigate fiber release from a specific product type (gaskets, packing, brakes, pipes, joint compounds, etc.) and specific worker activities (sanding, mixing, drilling, grinding, cutting, etc.). Unlike historic studies, which are often limited in data regarding site conditions, these simulations are performed in reproducible conditions. Many of these studies also involved the collection of proximal air samples: bystander PBZ, area, or both.
This presentation will share a summary of that data as a metric for evaluating models of asbestos fiber migration.