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What factors determine your Cleanroom Classification?

Feb 18, 2022 9:15:00 AM / by The Pegasus Team

Cleanrooms are essential to your operation, and the classification needs to be in line with your business needs. The classification of your cleanroom is critical, especially for company clients intent on making sure they are getting the highest quality of a product. The ISO classification says more about your company than you might know.

What are the levels of certification and the needs of the cleanroom to ensure they are met and maintained? Here they are:

Industries Needing Clean Rooms

The industries that use clean rooms most include:

  • Military and aerospace research
  • Life sciences
  • Food processing
  • Computer server farms
  • Computer chip manufacturing
  • Medical device manufacturing
  • And more

Cleanroom Classification Factors

Cleanrooms have different International Organization for standardization or ISO standards, and these standards are international and therefore understood by customers worldwide. The standards we are using are US FED STD 209E.

ISO8 - ISO 8 allows for a maximum particulate count of 100,000 ≥0.5 microns (um) per foot area. Seven hundred particles are the maximum particles ≥5 um per foot area.

ISO7 - Reduces the particulate counts to 10,000 ≥0.5 um and 70 ≥5 um.

ISO6 - This is the next level allowing 1,000 ≥0.5 um and 7 ≥5 um

ISO5 - 100 particles ≥0.5.

ISO4 - ISO4 introduces particulate counts for even smaller particles per square area. They are:

  • 350 ≥0.1 um 
  • 75 ≥0.2 um 
  • 30 ≥0.3 um 
  • 10 ≥0.5 um

ISO3 - The final US FED STD:

  • 35 ≥0.01 um
  • 7 ≥0.2 um
  • 3 ≥0.3 um
  • 1 ≥0.5 um

Our cleanroom cleaning process guide is an excellent tool for facilities managers wanting more comprehensive information on maintaining and improving their cleanroom ISO rating. Download a copy today.

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What are the Main Factors that Help Determine Cleanroom Classification?

Cleanroom maintenance is constant. Perform maintenance daily, weekly, monthly, and quarterly to maintain an area that needs this cleaning.

Equipment Maintenance

Cleanrooms might use specific equipment that needs to be specifically maintained to prevent organic contaminants from spreading. Also, cleanrooms use HEPA filters and ionizing grids that need regular maintenance.

When maintaining equipment, preventing the spread of grease, and containing its airborne molecular contamination (AMC), tremendous precautions need to be taken. The equipment must be isolated, and the maintenance worker must be fully gowned and wearing three pairs of latex gloves to prevent the spread of grease.

Filters need to be vacuumed every three months to remove particles. Clean ionization grids should and recalibrated every six months.


Cleanliness is the most critical aspect of cleanroom maintenance and meeting the required standards for your cleanroom classification. Cleaning needs to be constant, including those working in the cleanroom wiping down surfaces as required. Daily cleaning (before the shift begins) and weekly cleaning are necessary. Cleaning can have additional requirements when performed on hospital cleanrooms, pharmacy cleanrooms, and research center cleanrooms, to name a few.

Any work performed in a cleanroom will dirty it. Movement and even wiping down work areas create particles. All items brought into the cleanroom need to be wiped down with de-ionized water, regardless of how clean they seem. Cleanliness is considered a four-part operation of environment, tools, processes, and people. All staff has to be dedicated and routinely reminded of the need for cleaning.


The higher the ISO level, the more intensive and frequent cleaning becomes. Here are the basic requirements for each cleaning:

Daily Cleaning

  • It needs to be done before a shift and includes moping and vacuuming to dry.
  • A HEPA filter vacuum is used to vacuum walls.
  • All windows and pass-throughs need to be washed and wiped dry.
  • Employees need to wipe down all work areas at the end of the shift and maybe even more frequently.
  • Supplies and products need always to be properly stored to prevent contamination.

Weekly Cleanroom Cleaning

  • Use a specific detergent and distilled water to mop floors with a HEPA filter vacuum used for drying.
  • Walls receive the same treatment.

As Needed Cleaning

  • Wash ceilings regularly to remove deposits and residue.
  • Periodically wipe down area light lenses.
  • Sticky mats need to be changed the minute they show wear.

Antibacterial Fogging

Antibacterial fogging deserves special mention as an occasional cleaning practice. Biological contaminants can be especially problematic for cleanrooms. Hydrogen peroxide fogging uses aerosolized hydrogen peroxide to destroy bacteria, mold, and microbes. It is a safe and effective cleaning method that leaves no residue behind. Employees can return to the cleanroom after 24 hours of cleaning.

Educating Staff

Staff responsibilities and commitment to cleaning are crucial. As you’ve seen, every movement or touch impacts the number of particles in the cleanroom. It can be challenging for staff to imagine such enormous repercussions from minor activities or just how clean a cleanroom must be to meet ISO standards. Just telling someone that the difference can be between millions of particles in a one-foot area and seventy, and it isn’t easy to understand such a magnitude of difference.

Training staff thoroughly and often is one of the most essential activities in the entire facility. Once trained, reminders need to be every day using signs and mentions of benchmarks being met or not met.

Achieving High Cleanroom Classifications

As your status is checked for cleanroom compliance with ISO standards, certification increases can happen with maintained filters and ionizers and a consistent focus on cleaning. Higher ISO ratings mark maintenance success and a value enhancer for the company. Anytime a company can market itself as achieving high ISO standards, it adds value to its products.

Cleanroom cleaning classification is essential to your company and reflects your contribution and dedication, which is undoubtedly appreciated company-wide. Cleaning is the most mission-critical aspect of maintaining and achieving ISO standards.

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Posted in: Cleanroom

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