What Do ISO 14644 Cleanroom Classes Mean for Cleaning?

What does each ISO class number actually measure?

Each class is a ceiling on particle counts at stated particle sizes, measured with a particle counter at defined sampling locations. The scale is logarithmic: every step down in class number allows one-tenth as many particles. ISO 14644-1 classifies a room in one of three occupancy states, as-built, at-rest or operational, and the state matters, because a room certified at rest can read much higher once people and equipment are working in it. Ongoing monitoring to show the room stays in its class is covered by ISO 14644-2.

Older names from the cancelled US Federal Standard 209E still circulate. Class 100 roughly matches ISO 5, Class 10,000 matches ISO 7 and Class 100,000 matches ISO 8. The old system counted particles per cubic foot; the ISO system counts per cubic meter.

How do ISO 14644 cleanroom classes change garments, tools and chemistry?

People are the largest particle source in most cleanrooms, so the first thing that tightens as the class number drops is what the cleaner wears. Tools follow: a mop head or wiper that sheds fibers can push a room out of its class on its own. Chemistry tightens too, because residues become particles once they dry and flake. The pattern below is typical rather than mandatory; your SOP governs.

Technique changes with the class as well. In the cleaner rooms, crews work top to bottom and from the far wall toward the exit, use single overlapping strokes rather than scrubbing back and forth, and keep the number of people inside to the minimum the work allows.

Does a cleaner class mean more frequent cleaning?

Usually, yes, though the frequency comes from risk assessment and monitoring data rather than from ISO 14644 itself. Critical zones are often wiped before and after each operation or shift, ISO 7 floors and work surfaces are commonly cleaned daily, and ISO 8 support rooms may share a daily floor clean but space out walls and ceilings further. When monitoring results trend upward, frequency is the first lever a quality team pulls, and the change goes through change control so the SOP and the logs stay in step.

What a class number does not tell your cleaning crew

ISO 14644-1 counts non-viable airborne particles only. It says nothing about bacteria or mold, nothing about what is sitting on a surface, and nothing about chemical residue. Those limits come from other sources, and a cleaning program has to answer to them as well.

• Microbial limits come from GMP: EU GMP Annex 1 grades A to D for sterile manufacturing, FDA guidance on aseptic processing, or USP chapter 797 action levels in compounding pharmacies
• Surface particle and chemical cleanliness have their own parts of the series, ISO 14644-9 and ISO 14644-10
• Annex 1 grades map onto two ISO classes: Grade B is ISO 5 at rest but ISO 7 in operation, and Grade C is ISO 7 at rest but ISO 8 in operation
• Operational counts include the cleaning crew, so poor technique can push a passing room out of limits during a shift

Questions to settle with a contractor before the first clean

A contractor cannot work to the right class if nobody has written the class down. Before service starts, agree on a room list showing each room's class and occupancy state, the garment set for each, the zones the contractor touches and the zones operators keep, which agents and wipers are approved and who supplies them, the order in which rooms are cleaned, and what triggers an extra clean, such as an excursion or maintenance work inside the suite.

How EBS works within your room classifications

EBS runs cleanroom programs that are aligned with ISO and GMP requirements: full gowning, strict entry and exit discipline, non-shedding tools, HEPA-filtered vacuums and lint-free cloths, with each visit recorded in cleaning logs and service reports. The walkthrough begins with your room list, so the supervisor can note every class and the procedure that governs it and price the work room by room. Crews travel from the EBS office in Corona.