Air Movement Visualization in the Workplace: Current Methods and New Approaches

Abstract

Airflow visualization in the workplace to assess containment, ventilation, or general air movements is often carried out using smoke tracers. The most prevalent method uses a disposable smoke tube that generates a plume of concentrated sulfuric acid fume. However, use of the smoke tube exposes occupational hygienists to the risk of sulfuric acid exposure through inhalation or dermal contact, as well as injury from sharps. Following concern over the potential health hazard associated with smoke tube usage, alternative flow visualization methods and technologies have been reviewed. Methods of generating smoke or bubbles other than using smoke tubes suitable for visualizing air movements include heated element smoke generators, combustion generators, generation of metallic chlorides and ammonium chloride, generation of neutral density bubbles, and water fog generation. Some of these methods are applicable in specific workplace situations. However, there is no commercially available smoke or bubble generator currently available that matches the smoke tube for cost effectiveness, ease of use, and wide applicability, while also reducing the potential health risks associated with smoke tube usage. Despite this, certain technologies, in particular water/glycerol smoke generation using heated element generators, have the potential to be developed into viable alternatives to the smoke tube. Thus, with further development, an air movement visualization method that poses a significantly lower health hazard than the smoke tube is feasible.

Reentry

“…The tracers, which can be released and followed visually, have been evaluated by Maynard et al (2000) as noted in Table 3.6. The most widely used tracers for small release rates are the "smoke tubes," a misnomer since the released tracer is a fume, not smoke.…”

“…Four additional tracers worthy of comment were not considered by Maynard et al (2000). Dry ice-water is used by the semiconductor industry where particle release in the cleanrooms of the fabrication bays is not permitted for product quality reasons (SEMI, 2000).…”

“…(BOHS, 1987, Courtesy of British Occupational Hygiene Society. ) In the conclusion of their comprehensive review Maynard et al (2000) state, "Until a viable alternative is designed for the smoke tube it remains the most versatile choice for routine use in the workplace to monitor airflow patterns and assess control. "…”

“…In applications where high tracer generation rates are required, such as tracking the reentry of contaminants from exhaust stacks, a variety of candles and canisters Maynard et al (2000). and smoke generators are available.…”