What are laboratory cleanrooms?
— Equipo JP Selecta
A cleanroom is an environment designed to control the concentration of particles and, where the process requires it, microbiological contamination.
A cleanroom integrates ventilation, filtration, pressures, materials, procedures and staff behaviour to maintain repeatable environmental conditions. For this reason, when asking what a cleanroom is, the answer must include both the physical space and the control system that makes it work.
Its purpose depends on the activity: protecting an analytical sample, preventing cross-contamination during cell culture, preserving the reliability of an assay or protecting a sensitive product. The level of cleanliness is selected on the basis of the actual risk of the process; not all operations need the same classification or the same degree of segregation.
What are cleanrooms designed for?
Cleanrooms are designed to reduce and control the sources of contamination that can compromise a result, a process or the safety of staff. The aim is not to eliminate all risk, but to keep it within defined and verifiable limits.
In a laboratory, a particle, a microorganism or a misdirected airflow can invalidate an assay, alter a clinical result or encourage cross-contamination. In pharmaceutical manufacturing, the impact can extend to an entire batch. That is why the cleanroom is part of the quality system: environmental design, operation and records must demonstrate that the process is carried out in a controlled manner.
Main characteristics of a cleanroom
The performance of a cleanroom depends on elements that act in a coordinated way. A filter alone cannot sustain an ISO classification: the installation, operating routines and maintenance must keep the room in a state of control throughout the activity.
- Air filtration and air changes: the air is treated and renewed to limit the build-up of airborne particles. The efficiency required depends on the class of the area and the criticality of the process.
- Airflow and pressure cascade: air must move from the cleanest areas to the less clean ones. Usually, the most demanding areas are kept at a higher pressure to make it harder for uncontrolled air to enter when a door is opened.
- Controlled access: airlocks, changing rooms and pass-through hatches reduce direct transfer between environments with different classifications. The entry protocol for staff and materials is as important as the physical construction.
- Surfaces suitable for cleaning: walls, floors, ceilings and furniture must be smooth, continuous, resistant to cleaning agents and have as few hard-to-reach areas as possible. This limits the release and build-up of particles.
- Monitoring: reading differential pressure, temperature, humidity, air velocity and particles makes it possible to detect deviations before they affect the process. Acceptable values must be defined on the basis of the design and the risk assessment.
Types of cleanroom
Cleanrooms are classified by the maximum concentration of airborne particles.
ISO 14644-1 defines the classification according to the concentration of airborne particles and sets out how to determine it using particle counters at defined sampling locations.
The class chosen must reflect the risk and the operation carried out, not a generic preference for a stricter class.
| ISO class | Typical use | Particles ≥ 0.5 µm per m³ (max.) |
|---|---|---|
| ISO 5 | Critical areas and localised aseptic operations | 3,520 |
| ISO 7 | Preparation and support areas with high requirements | 352,000 |
| ISO 8 | Access areas, preparation or controlled storage | 3,520,000 |
The table gives indicative examples of use. The final assignment of a class requires an assessment of the product, the method, the workload, the number of operators and the barrier measures available.
Cleanroom regulations
Cleanroom regulations are structured around technical standards and sector-specific requirements. ISO 14644-1 establishes the classification of air cleanliness by particle concentration and covers classes from ISO 1 to ISO 9; the lower the number, the lower the permitted concentration.
ISO 14644-2 complements this approach with the monitoring needed to demonstrate that performance is maintained.
In the manufacture of sterile medicinal products, EU GMP Annex 1 requires a contamination control strategy (CCS): facilities, equipment, staff, cleaning, validation and monitoring must work as a system.
For hospital areas or other regulated environments, additional requirements may apply. Compliance is therefore not achieved by purchasing a single piece of equipment: the design must be documented, the installation qualified and operating procedures established in line with the intended use.
Cleanroom maintenance
Cleanroom maintenance combines preventive upkeep, metrological verification and trend review.
The plan must define what is measured, by which method, which limits apply, who reviews it and how to act in the event of a deviation. Frequencies are justified by the ISO class, the process risk and the history of results, not by a universal schedule.
- HEPA filter integrity: verified by an aerosol leak test with a photometer when this is part of the qualification plan. The pressure drop and the general condition of the ventilation system are also checked.
- Particle counting: performed with a calibrated counter in the states defined for the room, for example at rest and in operation. The comparison with the established limits must be recorded.
- Airflow and pressure: air velocity, air changes and differential pressure are checked against the design values. Alarms, pressure gauges and probes only add value if they are calibrated and their records are reviewed.
- Microbiological control: sampling of viable particles in the air and on surfaces is established when the process requires it. Results are interpreted as trends and together with incidents relating to cleaning, staff, materials and operation.
- Documentation: each verification must identify the date, equipment, result, person responsible and decision taken. This traceability turns measurement into useful evidence for investigating deviations and handling audits.
The role of equipment in laboratory cleanrooms
Equipment must support the contamination control strategy without becoming a new source of risk.
A biological safety cabinet or laminar flow cabinet provides a working area with filtered airflow for specific applications, but it does not replace the classification or validation of the entire room.
The selection must take into account the type of protection required (product, operator, environment or a combination), the method and the workload.
For processing materials, media or waste, our laboratory autoclaves make it possible to integrate steam sterilisation processes compatible with the operating workflow.
Ovens and incubators are equally relevant when the method requires incubation, culture or reproducible thermal control. The traceability of parameters and the maintenance of this equipment must be incorporated into the validation plan for the area.
The practical decision begins by mapping the movement of people, samples and materials; it continues with the selection of the right equipment and ends with cleaning, maintenance and documented control procedures. In this way, equipment stops being a set of independent devices and becomes a coherent part of environmental control.