Impact of air-handling system exhaust failure on dissemination pattern of simulant pathogen particles in a clinical biocontainment unit

Jennifer Therkorn, David Drewry, Thomas Pilholski, Kathryn Shaw-Saliba, Gregory Bova, Lisa L. Maragakis, Brian Garibaldi, Lauren Sauer

Research output: Contribution to journalArticlepeer-review

Abstract

Biocontainment units (BCUs) are facilities used to care for patients with highly infectious diseases. However, there is limited guidance on BCU protocols and design. This study presents the first investigation of how HVAC (heating, ventilation, air-conditioning) operating conditions influence the dissemination of fluorescent tracer particles released in a BCU. Test conditions included normal HVAC operation and exhaust failure resulting in loss of negative pressure. A suspension of optical brightener powder and water was nebulized to produce fluorescent particles simulating droplet nuclei (0.5-5 μm). Airborne particle number concentrations were monitored by Instantaneous Biological Analyzers and Collectors (FLIR Systems). During normal HVAC operation, fluorescent tracer particles were contained in the isolation room (average concentration = 1 × 104 ± 3 × 103/Lair). Under exhaust failure, the automated HVAC system maximizes airflow into areas adjacent to isolation rooms to attempt to maintain negative pressure differential. However, 6% of the fluorescent particles were transported through cracks around doors/door handles out of the isolation room via airflow alone and not by movement of personnel or doors. Overall, this study provides a systematic method for evaluating capabilities to contain aerosolized particles during various HVAC scenarios. Recommendations are provided to improve situation-specific BCU safety.

Original languageEnglish (US)
Pages (from-to)143-155
Number of pages13
JournalIndoor Air
Volume29
Issue number1
DOIs
StatePublished - Jan 2019

Keywords

  • air-conditioning
  • clinical biocontainment unit
  • exhaust failure
  • fluorescent aerosol tracer
  • heating
  • isolation unit
  • pathogen transmission
  • ventilation

ASJC Scopus subject areas

  • Environmental Engineering
  • Building and Construction
  • Public Health, Environmental and Occupational Health

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