A continuing challenge in occupational hygiene is that of estimating exposure to the multitude of airborne chemicals found in the workplace and surrounding community. Occupational exposure limits (OELs) have been established to prescribe the acceptable time weighted average for many different chemicals. Comparing the OELs to the measured workplace concentration allows occupational hygienists to assess the health risks and the need for control measures. Hence, methods to more effectively sample contaminants in the workplace are necessary to ensure that accurate exposure characterizations are completed. Evacuated canisters have been used for many years to collect ambient air samples for gases and vapors. Recently, increased interest has arisen in using evacuated canisters for personal breathing zone sampling as an alternative to sorbent samplers. A capillary flow control device was designed at McGill University mid 1990s. The flow control device was designed to provide a very low flow rate to allow a passive sample to be collected over an extended period of time. This research focused on the development and evaluation of a methodology to use a small canister coupled with the capillary flow controllers to collect long term time weighted air samples for gases and vapors. / A series of flow rate experiments were done to test the capillary flow capabilities with a 300 mL canister for sampling times ranging from a few minutes to over 40 hours. Flow rates ranging from 0.05 to 1.0 mL/min were experimentally tested and empirical formulae were developed to predict flow rates for given capillary geometries. The low flow rates allow for the collection of a long term air sample in a small personal canister. / Studies to examine the collection of air contaminants were conducted in laboratory and in field tests. Air samples for six volatile organic compounds were collected from a small exposure chamber using the capillary-canisters, charcoal tubes and diffusive badges at varied concentrations. The results from the three sampling devices were compared to each other and to concentration values obtained by an on-line gas chromatography. The results indicate that the capillary-canister compares quite favorably to the sorbent methods and to the on line GC values for the six compounds evaluated. / Personal air monitoring was conducted in a large exposure chamber to assess the effectiveness of the capillary-canister method to evaluate breathing zone samples. In addition, field testing was performed at a manufacturing facility to assess the long term monitoring capabilities of the capillary-canister. Precision and accuracy were found to parallel that of sorbent sampling methods. / The capillary-canister device displayed many positive attributes for occupational and community air sampling. Extended sampling times, greater capabilities to sample a broad range of chemicals simultaneously, ease of use, ease of analysis and the low relative cost of the flow controller should allow for improvements in exposure assessment.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84428 |
| Date | January 2002 |
| Creators | Rossner, Alan |
| Contributors | Farant, Jean-Pierre (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Epidemiology and Biostatistics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001973910, proquestno: AAINQ88572, Theses scanned by UMI/ProQuest. |
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