A cleanroom is a controlled environment designed to limit contamination—especially tiny airborne particles you may not be able to see, such as dust, fibers, skin flakes, and residue from everyday materials. In some industries (especially pharmaceutical and biotech environments), contamination can also include microorganisms like bacteria and fungi.
Cleanrooms exist because in modern manufacturing and science, contamination that looks “small” in everyday life can cause serious issues—product defects, equipment failures, safety risks, and regulatory non-compliance. At SOSCleanroom, we focus on helping organizations understand cleanroom expectations and support long-term control through best-in-class cleanroom consumables and practical guidance.
Many rooms can look clean. Fewer rooms are measurably clean.
When someone says a room is “clean”, that can be subjective. When a room is “ISO-classified”, it means the room’s air cleanliness has been measured and shown to meet a specific cleanliness level defined by an international standard.
In practical terms: ISO classification turns “clean” into a number—based on particle counts in a measured volume of air.
Not automatically.
A cleanroom typically refers to controlling airborne particles (and sometimes microorganisms, depending on the industry). Sterile means “free of viable microorganisms,” which generally requires additional validated sterilization methods, microbiological control programs, and stricter operational controls.
In other words: sterile areas are highly controlled, but not all cleanrooms are sterile.
ISO stands for the International Organization for Standardization. ISO publishes international standards so customers, suppliers, and auditors can align on consistent requirements globally.
ISO 14644 is the primary family of cleanroom standards used worldwide. Different parts of ISO 14644 address classification, testing, monitoring, and operations (day-to-day practices used to keep cleanroom performance in control).
What do ISO 5, ISO 7, and ISO 8 mean? These are air cleanliness classes based on particle limits in the air.
- Lower number = cleaner air (fewer particles allowed)
- Higher number = less strict (more particles allowed)
In the United States, many sterile manufacturing expectations are driven by FDA current Good Manufacturing Practice (cGMP) guidance and regulations. Globally, another major benchmark is the European Union’s EU GMP Annex 1, titled “Manufacture of Sterile Medicinal Products.”
Annex 1 was published in 2022 with a stated timeline for coming into operation of August 25, 2023 (and a later date for one specific clause). The core idea is straightforward: sterile operations must be controlled through a risk-based contamination control approach that is documented, measurable, and sustained over time.
Here are the Annex 1 concepts that most directly affect European cleanrooms (and influence global expectations):
- Grades A, B, C, and D for sterile operations: Annex 1 describes four cleanroom/zone grades used in sterile medicinal manufacturing. In plain terms, Grade A is the highest-control zone where the most critical, exposed sterile work occurs. Grades B–D support or surround critical activities with decreasing levels of control.
- “At rest” vs. “in operation” performance expectations: European sterile cleanrooms are commonly evaluated both when equipment is running without operators (at rest) and during actual work with operators and interventions (in operation).
- CCS (Contamination Control Strategy) is central: Annex 1 expects a documented, facility-wide plan that connects contamination risks and controls across premises, equipment, utilities, personnel, materials, cleaning/disinfection, and monitoring.
- Barrier technology emphasis (where appropriate): Annex 1 encourages reducing direct human interventions in critical zones using technologies such as RABS (Restricted Access Barrier Systems) and isolators.
- More focus on monitoring and trends: Annex 1 places strong emphasis on environmental and process monitoring that is designed intelligently, reviewed routinely, and used to detect drift early.
- Validated cleaning and disinfection programs: Risk-based disinfectant effectiveness validation and practical rotation strategies (including sporicidal use where appropriate) are common expectations.
Bottom line: for European sterile cleanrooms, Annex 1 pushes teams toward stronger CCS, reduced human intervention where possible, and a higher expectation for monitoring, documentation, and continuous improvement. For U.S. teams, Annex 1 is often used as a useful secondary benchmark—especially for global supply chains or organizations aiming to strengthen contamination control maturity.
- ISO 14644-1 overview (ISO): https://www.iso.org/standard/53394.html
- EU GMP Annex 1 (European Commission PDF): https://health.ec.europa.eu/system/files/2022-08/20220825_gmp-an1_en_0.pdf
- FDA sterile drug products (aseptic processing) guidance portal: https://www.fda.gov/
- ASTM (test methods and standards): https://www.astm.org/
- IEST (contamination control recommended practices): https://www.iest.org/
SOSCleanroom supports critical environments with best-in-class cleanroom consumables and practical guidance that helps teams stay consistent, audit-ready, and in control.