Notes on Fume Hoods and Biological Safety Cabinets

Course Overview

• Course offered by the College of Anderson, focusing on safety in laboratory settings crucial for preventing accidents and ensuring compliance with health regulations.

• Key topics include detailed operations, safety protocols, and compliance standards for Biological Safety Cabinets (BSC) and Fume Hoods, emphasizing the importance of worker and environmental safety in laboratory procedures.

Readings

• CSMLS Laboratory Safety Guidelines (9th Ed.) by Eoin O’Grady - Focus on Section 6.8: Biological Safety Cabinets

  • Pages 37-48 are crucial for understanding BSC functions and safety specifications, including evaluation criteria for effective laboratory practices.

Course Objectives

• Understand the functionalities of BSC and Fume Hoods, including their design principles and operational standards that protect laboratory personnel and the environment.

Biological Safety Cabinet (BSC)

Purpose

• Provides primary containment for handling human pathogens, significantly reducing airborne exposure risks.

• Ensures the safety of the worker and keeps samples uncontaminated through effective filtration and airflow control methods.

Uses

• Ideal for procedures with:

  • Infectious aerosols that pose a risk of airborne transmission.

  • High concentrations of infectious materials requiring stringent containment.

  • Large volumes of infectious materials that necessitate secure handling practices.

Function

• Air supply and removal systems are designed to minimize the escape of aerosols, incorporating advanced filtration techniques.

• Most critical component: HEPA filter - Densely pleated filter composed of glass and paper fibers, which removes biological particles efficiently by trapping particles as small as 0.3 µm, recognized as the most difficult size to filter.

HEPA Filters

Standards

• Tested based on removing 0.3 µm particles, the hardest to filter, to ensure high efficiency.

• Filters must be:

  • Tested and certified during installation and relocation

  • Evaluated annually to maintain compliance and effectiveness in particle removal.

Classes of BSC

Class I

• Air does not re-circulate; unwanted air is expelled after HEPA filtration, ensuring no contamination to product or environment.

• Protects the operator from biohazards without compromising sample integrity, making it suitable when the product is not at risk of contamination.

Class II

• Designed for personnel, product, and environmental protection, providing a balanced containment approach.

• Suitable for laboratories with containment levels 2, 3, and 4, accommodating various safety needs based on the type of work conducted.

• Divided into types based on:

  • Construction materials, ensuring durability and chemical resistance.

  • Airflow velocities and patterns tailored to different laboratory procedures.

  • Exhaust systems designed to mitigate chemical and biohazard risks effectively.

Class III

• Fully enclosed, gas-tight design that prevents any exposure to hazardous materials.

• Equipped with double HEPA filters for exhaust, ensuring maximum contaminant removal.

• Used for handling level 4 pathogens, safeguarded with an autoclave for decontaminating removed items, facilitating safe disposal practices.

Class II Types Comparison

Safe Practices in BSC

• Essential to maintain airflow; do not block grilles to ensure effective airflow dynamics.

• Follow workflow protocols for clean and dirty items to minimize cross-contamination risks.

• Ensure disinfection procedures are in place before and after usage, employing appropriate agents that meet safety standards.

Spill Cleanup Procedure in BSC

1. Leave fan on to maintain airflow, preventing contaminants from escaping.

2. Cover spills with absorbent paper towels to contain the spill.

3. Circulate disinfectant carefully around the towels, ensuring thorough coverage.

4. Wait 30 minutes before removal using forceps to allow adequate contact time for disinfection.

5. Decontaminate catch trays and clean thoroughly with appropriate agents to ensure complete safety.

UV Radiation in BSC

• Generally discouraged due to limited effectiveness and potential hazards.

• Recommended to use as a supplementary disinfection method only, not as the primary method due to inconsistent efficacy.

• Regular maintenance and testing are essential for safety, ensuring UV systems are functioning properly.

• Do not operate UV during human presence due to risks associated with radiation exposure, emphasizing the need for safety protocols.

Fume Hood Overview

Purpose

• Designed to control exposure to hazardous chemicals, protecting laboratory personnel from toxic fumes.

• Efficiently remove chemical fumes and aerosols from the work area to maintain a safe environment for laboratory activities.

Types

• Ducted Fume Hoods: Air expelled outside the building, ensuring complete removal of toxic substances.

• Recirculating (Ductless) Fume Hoods: Filter fumes through HEPA or other filters and return safe air back into the laboratory, emphasizing energy efficiency and reduced environmental impact.

Maintenance

• Periodic inspections required to ensure no blockages; verify that all components are functioning correctly to maintain safety and operational integrity.

Differences Between BSC and Fume Hood

• BSC is suited for biological agents requiring containment, whereas Fume Hood is designed primarily for hazardous chemicals, focusing on minimizing inhalation risks.

• BSC protects the environment, user, and material simultaneously, while Fume Hood primarily focuses on user safety.

• BSC must include HEPA filters to ensure biological safety; Fume Hoods may not require HEPA filtration depending on their design and application.

• Fume Hoods exhaust air outside the laboratory, while BSCs do not expel air without ensuring proper decontamination first.

Reference Materials

• Canadian Biosafety Handbook, Second Edition which outlines best practices and regulations for biosafety in laboratory settings.

• CSMLS Laboratory Safety Guidelines (8th and 9th Ed.) for essential safety advice and guidelines applicable to clinical laboratory environments.