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Research Roundup: Indoor Environmental Quality 3 (AIHce EXP 2022 OnDemand)
Course Description:
Recorded at AIHce EXP 2022

Presentations

Legionella Inhibition by Reducing Dissolved Oxygen in a Hot Water Test System — Avoiding the Risks and Adverse Effects of Available Control Methods

Reliable control of Legionella in building water systems with disinfectants is difficult, with frequent failures attributed to the loss of effective concentrations. Examining the published literature for all of the factors known to inhibit Legionella bacteria in plumbing systems revealed one critical factor that can be removed from water without diminishing its potability. Because Legionella bacteria are obligate aerobes, they are unable to colonize, amplify, or remain viable and virulent under anaerobic conditions (dissolved oxygen < 0.5 ppm). Reducing dissolved oxygen levels in a circulating hot water system does not adversely impact the plumbing materials or equipment but does interfere with bacterial respiration, metabolism, and viability. Laboratory studies have demonstrated that Legionella bacteria that are not culturable can no longer cause disease. In this study a model hot water plumbing system was maintained under anaerobic conditions. The viable Legionella introduced from distribution lines were prevented from amplifying, and concentrations were significantly reduced over time. An experimental hot water system, intentionally colonized with Legionella pneumophila in a laboratory, was later treated to reduce dissolved oxygen to less than 0.30 ppm. Even under conditions otherwise ideal for Legionella growth, when dissolved oxygen was maintained below 0.30 ppm, a 1 to 2 Log reduction of Legionella concentrations was achieved.

Quantitative Sampling of Terpenes Using Carbon Adsorbent-Based Thermal Desorption with Gas Chromatography
There is a growing interest in evaluating the long-term health effects of breathing air that contains high levels of terpenes. Cannabis is often grown in large quantities inside greenhouses. As cannabis grows it emits a variety of different terpenes into air. The same is true when the plants are being processed after harvesting. This creates the need for both reliable air sampling devices and analysis protocols. The greenhouse environment presents some unique challenges when trying to collect air samples for terpenes because of the high humidity levels present. The expansion of the cannabis industry makes it important to develop reliable sampling methods to quantitatively measure the terpene levels from both indoor & outdoor growing and processing operations. Having an air sampling device specifically designed for terpenes will help researchers better understand the possible health hazards of this rapidly growing industry. The use of thermal desorption is already an acceptable method for measuring volatile organic compounds from air. Here a new sampling tube and analysis protocol for capturing terpenes from air is presented using a new configuration of a thermal desorption tube.

Presentation Date:
05/25/2022

Presenters:
Janet Stout, Ph.D
J. David Krause, PhD, CIH
Jamie Brown

Session recordings are available for 90 days from purchase.


Stock #: AOD22_N3
ISBN #: 
Author/Editor: 

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