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Impact of air‐handling system exhaust failure on dissemination pattern of simulant pathogen particles in a clinical biocontainment unit
Author(s) -
Therkorn Jennifer,
Drewry III David,
Pilholski Thomas,
ShawSaliba Kathryn,
Bova Gregory,
Maragakis Lisa L.,
Garibaldi Brian,
Sauer Lauren
Publication year - 2019
Publication title -
indoor air
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.387
H-Index - 99
eISSN - 1600-0668
pISSN - 0905-6947
DOI - 10.1111/ina.12506
Subject(s) - hvac , doors , airflow , environmental science , isolation (microbiology) , aerosolization , ventilation (architecture) , respirator , particle counter , waste management , cleanroom , automotive engineering , air conditioning , engineering , materials science , mechanical engineering , aerosol , nanotechnology , medicine , chemistry , composite material , bioinformatics , organic chemistry , anatomy , inhalation , biology
Biocontainment units ( BCU s) 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 × 10 4 ± 3 × 10 3 /L air ). 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.