Analyzed and studied in laboratories each day, biological agents and toxins can be invisible, malicious storms, and much like how the presence of these pathogens introduces threats to society and life at varying intensity, the biosafety and necessary containment of the laboratories that handle them comes at a range as well.
The hazards associated with laboratory practices and techniques, safety equipment, and laboratory facilities are understood in several biosafety levels (BSLs). ANSI/ASSP Z9.14-2020: Testing And Performance-Verification Methodologies For Biosafety Level 3 (BSL-3) And Animal Biosafety Level 3 (ABSL-3) Ventilation Systems deals with the ventilation systems of biosafety level 3.
Below is a brief overview of BSLs.
Biosafety Level 1 (BSC-1)
BSC-1 is suitable for work involving well-characterized agents not known to consistently cause disease and present minimal potential hazard to laboratory personnel and the environment.
Class I Biosafety Cabinets (BSCs) provide personnel and environmental protection but not product protection.
Biosafety Level 2 (BSC-2)
More restrictive than BSC-1, BSC-2 laboratories work with agents associated with human diseases (i.e. pathogenic or infections organisms) that pose a moderate health hazard.
Class II biosafety cabinets contain partial barrier systems that rely on the movement of air to provide personnel, environmental, and product protection. Class II BSCs are further organized into several types—Type A1 (formerly Type A), A2 (formerly B3), B1, B2, and C1—classified by minimum average airflow velocity, as well as variations in exhaust.
You can learn more about Class II Biosafety Cabinets, as Specified in NSF/ANSI 49-2019 here.
Biosafety Level 3 (BSL-3)
At this level, work is performed with indigenous or exotic agents that may cause serious or potentially lethal disease through inhalation. While working in this level of laboratory containment applicable to clinical, diagnostic, teaching, research, or production facilities, personnel need specific training and competent supervision to handle pathogenic and potentially lethal agents.
Class III biological safety cabinets, or biosafety cabinets, (Class III BSC), offering maximum protection of the environment and the worker, are gas-tight and contain a non-opening, completely sealed, viewing window that is accessed using long, heavy-duty rubber gloves attached to ports in the cabinet. Both supply and exhaust air are HEPA filtered, and cabinet is maintained under negative air pressure of at least 0.50 in water gauge (w.g.) (120 Pascal [Pa]).
Animal Biosafety Level 3 (ABSL-3)
This level of laboratory containment involves practices meant for work with laboratory animals infected with indigenous or exotic agents, agents that present a potential for aerosol transmission, and agents causing serious or potentially lethal disease. Much as with BSL-3 (in relation to BSL-2), ABSL-3 containment builds on the standard practices, procedures, containment equipment, and facility requirements of ABSL-2.
Biosafety Level 4 (BSC-4)
While incredibly rare, as the highest level of biological safety, a BSL-4 lab consists of work with highly dangerous and exotic microbes and is subject to stringent containment requirements.
BSL-3/ABSL-3 Labs and ANSI/ASSP Z9.14-2020
As discussed in the Foreword of ANSI/ASSP Z9.14-2020, over 1,000 laboratories and animal facilities designed and operated at biosafety level 3 (BSL-3) or animal biosafety level 3 (ABSL-3) have been constructed in the United States. The design of ventilation systems found in BSL-3/ABSL-3 laboratories is driven by criteria defined in several documents, including:
- Biosafety in Microbiological and Biomedical Laboratories (BMBL)
- U.S. Department of Agriculture Animal Research Service (USDA ARS) 242.1 Manual
- World Health Organization (WHO) Biosafety Guidelines: Biosafety Manual
- Standards published by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE).
However, these guidelines do not cover testing and performance verification methodology needed to ensure the safe operation of ventilation systems.
ANSI/ASSP Z9.14-2020 uses a risk assessment and performance-based approach to provide the technical specifications and background information needed for addressing the technical, engineering, and associated systems for ventilation within a BSL-3/ABSL-3 laboratory.
Harnessing the combined knowledge acquired over the years by biosafety professionals, design professionals, and owners/operators of BSL-3/ABSL-3 laboratories, ANSI/ASSP Z9.14-2020 ultimately helps assure the necessary environment for biocontainment, occupational health, and animal health. In other words:
“The purpose of ANSI Z9.14 is to provide a ‘one-stop’ resource for guidance to inspect and test the performance of a BSL-3/ABSL-3 laboratory ventilation system.”
Specifically, ANSI/ASSP Z9.14-2020 helps evaluate and inspect directional airflow, anterooms, primary containment systems, the building ventilation system, filtration, the integration of static caging systems (and related elements), document verification, pressure reversal, failure testing, qualifications of testers, HVAC testing, and leakage issues related to HVAC.
The testing and verification of ventilation systems in BSL-3/ABSL-3 labs consider supply, exhaust, directional airflow, biosafety cabinets, air filtration, exhaust stacks, fan failure scenarios, redundancy, and canopy hoods (autoclaves), as well as related systems like physical integrity, sealing and leakage factors, and airlocks.