Medical Laboratory Assistant/Technician Program - Safety Cabinets and Fume Hoods Notes

Course Objectives

• Function Overview:

  • Summarize the purpose and function of both Biological Safety Cabinets and Fume Hoods, understanding their relevance in laboratory settings where exposure to hazardous substances is a concern.

Biological Safety Cabinets (BSC)

Purpose of BSC

• Biological Safety Cabinets provide primary containment for activities involving:

  • Human pathogens, which include bacteria and viruses that can cause disease in humans.

  • Procedures that generate infectious aerosols, which pose a risk of airborne transmission.

  • High concentrations and large volumes of infectious materials, necessitating strict containment measures.

Functionality

• The air supply and removal system in BSCs is engineered to minimize the escape of aerosols that could pose health risks.

• A critical component of a BSC is the HEPA filter, which:

  • Effectively filters biological particles from the air, ensuring a sterile workspace.

  • Requires regular testing and certification to ensure its effectiveness and operational integrity.

HEPA Filter Standards

• The efficiency of HEPA filters is tested using 0.3 µm particles, which are among the most penetrating particle sizes.

• Testing requirements for HEPA filters include:

  • Upon installation, any relocation of the cabinet, and annually thereafter, or after any repairs or modifications.

Classes of BSC

1. Class I:

   • Features a non-recirculation system; HEPA filtered air is discharged to the atmosphere.

   • Primarily protects the operator from exposure without offering protection to the product being handled.

2. Class II:

   • Designed for simultaneous protection of personnel, the product, and the environment.

   • Contains multiple subtypes (A1, A2, B1, B2), each tailored for specific laboratory applications and requiring detailed understanding for proper usage.

3. Class III:

   • Represents a totally enclosed, gas-tight design with double HEPA filtered exhaust, ensuring maximum safety.

   • Suitable for handling level 4 pathogens, which are known for their high risk and potential for transmission, equipped with specialized safety features, including glove ports for manipulation of samples.

Subtypes of Class II BSCs

• Type A1 and A2:

  • Designed for work with biological materials but have restrictions when it comes to volatile toxic materials due to potential contamination risks.

• Type B1:

  • Capable of handling limited levels of toxic substances, providing a controlled environment for specific experiments.

• Type B2:

  • Features no recirculation and a 100% exhausted air system; suitable for procedures involving toxic and radionuclide substances, ensuring utmost safety for users.

Working in a Class II BSC

• It is essential to follow specific protocols to ensure safety and prevent contamination, including:

  • Adhering to start-up procedures, ensuring proper positioning relative to airflow, and performing regular airflow checks.

  • Maintaining cleanliness and organizational practices within the cabinet to avoid cross-contamination and ensure a safe workspace.

Spill Cleanup Procedures

• In the event of a spill within a BSC:

  • Keep the cabinet fan operational to minimize aerosol escape.

  • Utilize appropriate materials and procedures for disinfection and containment of spills, following five specific steps to effectively cleanup and decontaminate the area.

UV Radiation

• Use Limitations:

  • UV radiation is not recommended as a primary disinfection method; it should only serve as a secondary measure when other cleaning protocols are insufficient.

  • The use of UV equipment requires extensive training to ensure safe operational practices.

• Key Features:

  • UV radiation produces light at 254 nm, which has limited penetration capabilities.

  • The effectiveness of UV light in disinfecting surfaces diminishes with distance and time; therefore, regular testing and cleaning of UV systems are necessary to maintain their efficacy.

Fume Hoods

Purpose

• Fume Hoods are specialized equipment designed to control and minimize exposure to hazardous chemicals, ensuring the safety of laboratory personnel and the surrounding environment.

Operating Guidelines

• To function effectively:

  • Maintain the proper sash height, which is crucial for ensuring optimal airflow and protection.

  • Keep the work area clear of obstructions that could interfere with safe operations.

  • Regular maintenance and inspections are essential to ensure the fume hood is functioning appropriately, adhering to safety regulations.

Types of Fume Hoods

1. Ducted:

   • Directly vents hazardous air and fumes to the outside atmosphere, providing effective ventilation.

2. Recirculating:

   • Filters air and returns it to the room; suitable for certain applications but not for those involving highly toxic or volatile substances due to potential re-exposure risks.

Key Differences Between Fume Hoods and BSC

• Fume hoods are specifically used for handling chemical exposure, whereas BSCs are designed to protect against biological agents.

• Unlike BSCs, fume hoods do not include HEPA filters.

• Air from fume hoods is exhausted directly to the outside environment, while BSCs maintain a contained work area without direct external exhaust.

References

• Canadian Biosafety Handbook, Second Edition

• CSMLS Laboratory Safety Guidelines (8th or 9th Ed.) for regulations and best practices in laboratory safety processes.