Cleanroom Maintenance: Everything You Should Know

cleanroom maintenance

Cleanroom maintenance is a meticulous process that requires much planning and organization to ensure the necessary requirements are adhered to.

This post explains what a cleanroom is, its importance, and the proper cleanroom maintenance to keep it in spec. 

What is a Cleanroom?

A cleanroom is a well-controlled environment with low levels of pollutants, such as dust, chemical vapors, and airborne microbes. A cleanroom environment is designed to maintain specific levels of cleanliness depending on the requirements of the process conducted within the room. 

Depending on how ‘clean’ the cleanroom is, it’s given an ISO classification ranging from 1-9 or a Class M1-M6 according to Federal Standard 209E. ISO class 1 is the cleanest, basically a sterile room with only 100 particles of 0.1 microns or bigger for every cubic meter. 

Importance of a Clean Environment

Cleanrooms are used for various types of industries depending on their ISO classification. The cleaner the room, the more critical the applications.

For example, an ISO class 4 allows 10,000 particles at 0.1 microns or bigger for every cubic meter, making it suitable for electronics assembly, pharmaceutical production, and biotechnology.

Conversely, a highly sterile ISO class 1 cleanroom allows for nanotechnology research and semiconductor manufacturing, both of which are extremely sensitive to contamination. 

Steps on How to Maintain a Clean Cleanroom to Keep it in Spec

Here are the steps to follow for an ideal cleanroom environment.

Step 1: Inspect for Issues

Regular inspection of all cleanroom equipment is vital for the success of the products synthesized within. 

Cleanroom equipment needs regular care. The intervals of how often you maintain your equipment will depend on the type of industry conducted within the room.

Typically, ISO class 1 equipment is often inspected, cleaned, and maintained at shorter intervals compared to ISO class 7 cleanrooms.

Whenever inspection is due, visual assessments to identify any signs of wear, damage, or contamination should be conducted. Such inspection includes tools, machinery, and instrumentation used in the cleanroom environment. 

Further, to ensure the accuracy and reliability of the synthesized products, all equipment should be calibrated at their scheduled intervals. 

Such calibration is particularly important for devices that monitor environmental conditions, particle counts, and other critical parameters. Lastly, calibration certificates must be kept up to date. 

Step 2: Monitor Air Quality

You should check air quality metrics consistently to ensure that standards are continuously met. Particle counters should be used to measure amounts of particulate matter down to 0.1 microns or even below.

You should take the readings at multiple locations around the cleanroom because the issues are sometimes localized. 

In ISO class 1 cleanroom, air changes should be monitored per hour to ensure positive pressure and adequate filtration. You should also measure the temperature, humidity, and differential pressure across all filter banks. 

To further ensure the ideal air quality, you should choose the right air filters. HEPA filters are typically the best choice to trap particles down to 0.3 microns in size, removing dust, microbes, and other contaminants. 

If needed, ULPA filters can capture even smaller particles down to 0.12 microns. In addition to HEPA/ULPA filters, you should also install appropriate chemical filters if you need gas or vapor control. 

Filters should be regularly cleaned and replaced according to the manufacturer’s recommendations, as their performance degrades over time. 

Step 3: Constant Cleaning of Surfaces and Floors

The smallest amount of dirt, dust, or chemical residue in a cleanroom can lead to contamination issues, which is why specific cleanroom cleaning equipment is needed.

The cleanroom cleaning procedure should be done before the working personnel enter, as it’s mandatory for cleanroom maintenance.

Here’s how to clean a cleanroom:

  • Contaminated materials: All contaminated materials from previous procedures should be disposed of in designated double-bagged waste containers.
  • Walls and ceilings: Use damp, lint-free wipes or mops with cleanroom-approved solutions to gently wipe down walls and ceilings. Always work from top to bottom to avoid dripping onto cleaned surfaces.
  • Floors: The cleanroom should be damp mopped with appropriate detergents, followed by a HEPA-filtered vacuum to remove residual moisture particles. Corners and edges are especially susceptible to contaminants, so they should be cleaned thoroughly.
  • Work surfaces and equipment: All workstations, benches, knobs, levers, control panels, and equipment should be wiped with cleanroom wipes and disinfectants. 
  • Hatches and airlocks: Clean and disinfect door handles, seals, and any interior surfaces of pass-through hatches and airlocks to prevent contamination transfer between controlled environments. 

Step 4: Waste and Spill Management

Cleanrooms produce solid and liquid waste that must be dealt with to avoid releasing contaminants in the cleanroom. 

Examples of such waste include glass, needles, chemicals, and hazardous materials. Further, if spills occur, they should be cleaned up immediately using approved cleanroom mops, wipes, and neutralizing agents. 

Additionally, personnel should report all incidents and document all cleanup procedures to ensure that whatever contaminant is properly dealt with.

Step 5: Entry Protocols Should Be Clearly Established

Even the cleanest cleanrooms will be contaminated if entry protocols aren’t followed. Often cleanrooms should have an airlock system with interlocking doors to allow the opening of only one door at a time.

Personnel entering the room must wear the proper gowning apparel, which typically includes head/foot covers, masks, gloves, suits, and booties. Proper body cleanliness and hand washing with antibacterial soaps and solutions must be done before dressing even begins.

Cleanroom Standards & Classifications 

Cleanrooms have certain standards and classifications. The primary standards organizations that define cleanroom classifications are ISO and the US Federal Standard 209E.

Here are the classifications under each standard:

ISO Classifications

  • ISO Class 1: Allows no more than 10 particles of ≥0.1 μm per cubic meter.
  • ISO Class 2: Allows no more than 100 particles of ≥0.1 μm per cubic meter.
  • ISO Class 3: No more than 1,000 particles of ≥0.1 μm per cubic meter.
  • ISO Class 4: No more than 10,000 particles of ≥0.1 μm per cubic meter.
  • ISO Class 5: No more than 100,000 particles of ≥0.1 μm per cubic meter.
  • ISO Class 6: No more than 1,000,000 particles of ≥0.1 μm per cubic meter.
  • ISO Class 7: No more than 352,000 particles of ≥0.5 μm per cubic meter.
  • ISO Class 8: No more than 3,520,000 particles of ≥0.5 μm per cubic meter.
  • ISO Class 9: No more than 35,200,000 particles of ≥0.5 μm per cubic meter.

Federal Standard 209E Classifications (Conventional)

  • Class M1: Allows no more than 1 particle of ≥0.5 μm per cubic foot.
  • Class M1.5: Allows no more than 10 particles of ≥0.5 μm per cubic foot.
  • Class M2: No more than 100 particles of ≥0.5 μm per cubic foot.
  • Class M2.5: No more than 1,000 particles of ≥0.5 μm per cubic foot.
  • Class M3: No more than 10,000 particles of ≥0.5 μm per cubic foot.
  • Class M3.5: No more than 100,000 particles of ≥0.5 μm per cubic foot.
  • Class M4: No more than 100,000 particles of ≥0.5 μm per cubic foot.
  • Class M4.5: No more than 500,000 particles of ≥0.5 μm per cubic foot.
  • Class M5: No more than 1,000,000 particles of ≥0.5 μm per cubic foot.
  • Class M6: No more than 5,000,000 particles of ≥0.5 μm per cubic foot.

How Often Should You Check A Cleanroom

Here are the typical checks of cleanrooms along with how often they should be done:

  • Daily Checks: Particle counts, differential pressures, temperature/humidity, facility inspection.
  • Weekly Checks: Gowning inspection, cleaning efficacy, consumables inventory.
  • Monthly Checks: Airflow visualization, filter installation inspection, deeper facility inspection.
  • Quarterly Checks: Full particle mapping, filter leak scanning, pressure mapping
  • Annual Checks: Complete airflow balance study, filter penetration tests, and full HEPA certification.

More critical cleanrooms used for pharmaceutical or medical device manufacturing may undergo even more frequent checking on key parameters like differential pressures and particle counts. Unexpected shifts can indicate issues needing quick response.

How Often Does A Cleanroom Need To Be Recertified?

Full cleanroom recertification is typically conducted annually. This involves third-party testing and verification to confirm the cleanroom still meets the original ISO classification standards it was built and qualified to meet.

Key testing includes:

  • Particle count measurements at designated sampling points.
  • Filter leakage scans using discrete particle counters.
  • Airflow visualization analysis.
  • Airflow velocity, turbulence intensity, and directionality checks.
  • Air pressure differential monitoring.
  • Filter penetration tests using PAO.
  • Air change rate verification.
  • Room recovery checks after particle injection.

Any deficiencies uncovered must be corrected before certification is renewed. More rigorous cleanrooms may be recertified every 6 months. Facilities used for pharmaceutical processing often schedule recertification around major manufacturing events or equipment upgrades.


  • Cleanrooms are controlled environments used in various industries that require meticulous cleaning processes to maintain required ISO standards.
  • Maintaining cleanrooms involves inspecting issues, monitoring air quality, cleaning of floors and surfaces, managing waste, and ensuring protocols are followed upon entrance and exit of the area.
  • There are several standards and classifications for cleanrooms, depending on its purpose including ISO classifications and Federal Standard 209E Classifications.
  • There should be daily, weekly, monthly, quarterly, and annual checks of cleanroom inspection to ensure maintenance.