Cleanroom Biosafety Cabinet

Basics of Biological Safety Cabinet (BSCII) Decontamination

Isolators like fume hoods, bio-safety cabinets, and glove-boxes are used to create environments with low levels of environmental contamination such as biological agents, aerosol particles, and microbes. These contamination barriers improve pharmaceutical production outcomes and allow for more safe and flexible production environments. Isolators can potentially lower the installation and maintenance costs compared to large-scale cleanroom environments. This article focuses on the most fundamental cleaning and wiping procedures.

Isolators and Decontamination

Decontamination is the reduction or removal of biological or chemical agents, including non-active particles to non-hazardous levels to products, processes, or the environment by means of physical or chemical procedures.

Specifically, in pharmaceutical manufacturing environments, research laboratories, and hospital pharmacies, the effective decontamination of biological agents like bacteria, viruses, fungi, protozoa, prions, and spores is essential.

These separative devices have a controlled level of contamination, specified by the number of particles with a defined size per cubic meter, providing controlled environments that are specifically tailored to the needs of its operator. This classification of cleanrooms and isolators, however, is not taking into account specific requirements regarding biological contamination. In order to maintain the low levels of environmental pollutants, isolators have to be decontaminated on a regular basis.

Isolator Cleanliness

Isolator cleanliness levels are defined by different classifications, as shown in Table 1 and Table 2. These classifications are evaluating the environmental pollution by particles, however, not taking into account specific requirements regarding biological contamination. In order to maintain the low levels of environmental pollutants, isolators have to be decontaminated on a regular basis.

Quality supervisors in facilities using isolators have to determine the acceptable level of biological agents in their respective environment and decide on the method to achieve these levels. Several factors influence the choice of method and materials.

Potential Contaminants 

Isolators are used in a variety of industries working with different materials and requirements. Potential contaminants in isolators can, therefore, range from biological contaminants (e.g. pharmaceutical industry, hospital pharmacies), radionuclides (e.g. pharmaceutical industry, research laboratories), to general particulate contaminants (e.g. semiconductor industry).

Chemical Agents: Inactivation

Spills of hazardous chemical agents in isolators or potential reaction products immobilized on isolator surfaces require inactivation or dilution to non-hazardous levels. The chemicals and chemical processes used for inactivation depend on the contaminant.

Biological Agents: Disinfection and Sterilization

To reduce the level of biological agents in an environment, disinfectants/ sanitizers and sterilants can be used. Sanitizers and disinfectants are terms used in different industries for the same kind of product. Whereas the food and food-processing industry use the term sanitizers, the pharmaceutical industry, laboratories, and hospitals are predominantly using the term disinfectant.

Disinfection describes a process that eliminates many of all pathogenic microorganisms on inanimate objects, except bacterial spores¹. On the other hand, Sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out by physical or chemical methods². Depending on the biological agent and the material or media holding it, sterilization can be achieved through the application of heat, chemicals, irradiation, high pressure, or filtration. It is essential to understand the difference between both processes to assure that contamination level requirements are met. Whereas some commercial and technical literature us confusing readers by using both terms interchangeably, it should be noted that  Disinfection and  Sterilization describe two processes with very outcomes. It is not appropriate to talk about partial sterilization or even replace the word disinfection with sterilization.

The efficacy of sterilization depends on a number of factors like:

  • Prior physical cleaning (effective surface and biofilm reduction)
  • Presence of organic and inorganic load-level and type of microbial contaminants
  • Concentration of sterilant
  • Exposure time of sterilant
  • pH, temperature, and humidity of the environment
  • The geometry of object and spaces
  • Physical properties of objects
Frequent application of sterilization processes is facing two major challenges; the potential build-up of resistance against the used sterilization agent as well as disadvantageous interactions with humans and surfaces that get in direct contact with these agents. The applied processes have to be well understood in order to avoid these detrimental effects.
The efficacy of different sterilization methods has been evaluated and reported by a number of publications. Tested microbial agents include bacteria, spores, and viruses³†‡. As discussed in this article, microbiological agents may show a significant difference in resistance to the discussed sterilization methods. Therefore previously mentioned factors (the efficacy of sterilization depends on a number of factors such as in list one as well as the specific resistance to microbiological agents) play a vital role in the selection of the appropriate sterilization method.

Wipers for Cleanroom Isolator Cleaning & Decontamination

In isolators with processes using chemical agents, the successful inactivation of these agents precedes any removal attempt in order to avoid further contamination of the environment or reaction with the isolator surfaces and cleaning materials. After successfully inactivating hazardous chemicals, high absorbency wipes are used to physically remove the reaction products.
When choosing isolator cleaning tools and materials, it is recommended that operators introduce the least amount of particle and fiber generating materials into the isolator. Typically a cleanroom laundered 100% continuous filament polyester knit material with sealed edges is recommended for use to clean surfaces inside the isolator. Additionally, isolator cleaning tools with replacement covers that have been tested for particle and fiber release are appropriate to extend the reach of the cleaning area as well as providing ergonomic benefits to the operator.
One can also use cleanroom wipes with specific surface treatments to allow the wiper to capture and retain particulate contamination, resulting in more efficient cleaning and reduce likelihood or re-contamination of critical surfaces.
The recommended steps to be performed when cleaning a contaminated surface do not change and are the same for all kinds of contaminants.
  1. Always clean from the cleanest to the dirtiest surface
  2. Clean with overlapping strokes and change wiper surface with each stroke
  3. If using an isolator cleaning tool or mop, change out cover material with each surface side of the isolator

Biofilm Cleaning and Sanitation

In the case of isolators with biological contaminants, like bacteria, spores, and viruses, regular sterilization might seem to be sufficient in killing the microbial agents. However, it is extremely important that prior to sterilization, a physical removal of these contaminants is done in order to avoid a subsequent buildup of biofilms that would increase the resistance to sterilization attempts in the future. Biofilm is composed of polysaccharides that consist of carbon, hydrogen, and oxygen. Hydrogen and oxygen are most likely to be found in most isolators with natural atmosphere, leaving killed microbial agents behind would provide the required carbon for bacteria to reproduce and form new biofilms.

Standard Isolator Cleaning Procedure 

Developing a Standard Operating Procedure (SOP) for your isolators is a difficult task and depends on the very specific requirements of a facility’s processes and regulation in its industry.
As a rule of thumb, Table 3 can serve as a general guideline to develop your own SOP††.
Questions to ask yourself:
  • What contaminates am I concerned about?
  • Would they contaminate my processes (inside) or the environment (outside)?
  • Are these contaminants inert, chemical-, biological-, or radioactive?
  • What contamination limits have to be considered?
The use of an isolator cleaning tool should also be considered to allow efficient cleaning†† of hard-to-reach areas and guarantee an equal pressure distribution of your cleaning material (wipes/pads) on the isolator surface. The applied pressure is a determining factor in the physical removal of contaminants from a surface.


Proper decontamination and cleaning are critical to the long-term success of materials produced in these environments. Reducing the risk of cross-contamination starts with a full understanding of the type of potential contaminants introduced before, during, and after the production process. Sterilization and spraying with disinfectants alone are not enough to remove residual particles that could result in the buildup of biofilms. Proper wiping and rinsing protocols are needed to ensure the total removal of contaminants and the cleanliness of the isolator.
  1. Healthcare Infection Control Practices Advisory Committee (HICPAC), “Guideline for Disinfection and Sterilization in Healthcare Facilities”, 2008
  2. McDonnell, G.; Russell, A.D.; “Antiseptics and Disinfectants: Activity, Action, and Resistance” Clinical Microbiological Reviews, Jan. 1999, p. 147-179
  3. Mehmi, M.; Marshall, L.J.; Lambert, P.A.; Smith, J.C.; “Evaluation of Disinfecting Procedures for Aseptic Transfer in Hospital Pharmacy Departments” PDA Journal of Pharmaceutical Science and Technology, Vol. 63, No. 2, p. 123-138
  4. † Block, S.S.; ‘Disinfection, Sterilization, and Preservation” Philadelphia: Lea & Febiger 1991
  5. ‡ Siegerman, H. “Wiping surfaces Clean” A2C2 Magazine, April 2003
  6. †† “Isolator Cleaning Guide” 01 Aug 2010 Berkshire Corporation
© Dr. Thomas H. Treutler, CTO Berkshire Corporation

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Mel Meadows

Mel Meadows

Mel Meadows is a product specialist with over 13 years of experience. She’s a central source of expertise for thousands of industrial and critical-class products featured on the Production Automation web store. By working directly with manufacturers, Mel deciphers technical documentation and outlines product use in real-world environments. View her profile to learn more about proper techniques, protocol, and product usage in both industrial and cleanroom facilities.

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