Overview
This lecture covers filtration methods for removing microbes from air and liquids, focusing on HEPA and membrane filtration, especially when heat cannot be used for sterilization.
Filtration in Air
- HEPA stands for High-Efficiency Particulate Air filter.
- HEPA filters have pore sizes of 0.3 micrometers or smaller.
- HEPA filters are commonly used to remove microbes from air, especially in healthcare environments.
Filtration in Liquids
- Membrane filtration is used to remove microbes from heat-sensitive liquids.
- Membrane filters have pore sizes of 0.2 micrometers or smaller; some are as small as 0.08 micrometers.
- Membrane filtration can sterilize solutions by capturing bacteria, viruses, and prions without heat.
Applications of Membrane Filtration
- Used for sterilizing heat-sensitive materials such as vitamins, antibiotics, and vaccines.
- Vaccines are especially dependent on filtration due to their sensitivity to heat.
- Cold chain (continuous refrigeration) is critical for vaccine efficacy, but maintaining it is challenging globally.
Importance of Refrigeration and Heat Sensitivity
- Many vaccines lose effectiveness without proper refrigeration during transport and storage.
- Lack of reliable refrigeration is a global issue, making alternatives like filtration crucial.
- Ideal vaccines would not require refrigeration to ensure global effectiveness.
Key Terms & Definitions
- HEPA filter — Air filter with pore size ≤ 0.3 micrometers, used to remove airborne microbes.
- Membrane filter — Liquid filter with pore size ≤ 0.2 micrometers, used for sterilizing heat-sensitive solutions.
- Cold chain — The process of keeping vaccines refrigerated from production to administration.
Action Items / Next Steps
- Review filtration methods and their appropriate uses for air versus liquid.
- Consider the limitations of heat-based sterilization and when filtration is preferred.
- Prepare for further discussions on vaccines and the impacts of refrigeration needs.