A cleanroom can look spotless and still fail the moment someone measures it. Clean surfaces and gowned staff are only part of the story, because contamination control also depends on invisible factors such as filter integrity, airflow and pressure. This checklist covers seven tests that sit at the heart of a thorough cleanroom inspection in UAE hospitals, laboratories and manufacturing plants.
Test 1: Airborne particle count
A particle counter samples the air at locations chosen according to the room volume, and the results are compared with the ISO cleanliness class the room is meant to meet. The count can be taken in the as-built, at-rest or operational state, so it is worth agreeing which one applies before testing begins. This is the headline figure that shows whether the room still deserves its classification. A reading above the class limit is usually the first sign that filters, airflow or housekeeping need attention.
Test 2: HEPA filter integrity
Technicians challenge each installed HEPA filter with an aerosol and scan it with a photometer to find leaks. A damaged or poorly seated filter lets unfiltered air slip past the barrier the whole room depends on. Any leak the scan finds should be repaired and the filter retested before the room returns to use.
Test 3: Air velocity and air change rate
Air velocity is measured with an air velocity meter, while the air change rate is calculated from the total airflow, captured with an air capture hood, and the volume of the room. Together they show whether enough clean air is arriving to dilute and carry away particles. Low readings can point to loaded filters or HVAC balancing problems.
Test 4: Differential pressure
A digital manometer measures the pressure difference between each clean room and the spaces next to it. Cleanrooms are generally kept at positive pressure so air flows outward, while rooms that handle hazardous or biological materials may be set to negative pressure for containment. When readings drift outside the specified limits, contaminated air can move the wrong way through doors and gaps.
Test 5: Airflow direction and visualisation
A smoke generator releases visible fog so inspectors can watch, and record on video, how air moves through the room. The test confirms that airflow matches the design and exposes dead spots or turbulence where contamination could linger. It is best carried out after the velocity and pressure tests, so the pattern reflects a properly balanced system.
Test 6: Recovery
After a brief burst of particles is released, the room is monitored to see how long it takes to return to its specified cleanliness level. This matters because a cleanroom has to bounce back after people, equipment and activity disturb it, not just look good at rest. Slow recovery can indicate a filter leak or an air change rate that is too low.
Test 7: Temperature and relative humidity
A thermo-hygrometer records temperature and humidity over time to confirm they stay within the limits set for the room. Stable conditions protect products, processes and people, and humidity that drifts too high or too low can affect both materials and equipment.
Keeping the checklist current
Testing intervals depend on the cleanroom class, the industry and your own risk assessment, so agree a schedule with your inspector. Repeat the relevant tests after filter replacement, major maintenance or any change to the room layout. Many sites also add lighting level and sound level checks to the schedule. When arranging cleanroom testing Dubai operators should ask for a written report that records each method, instrument and result.
Why URS Labs?
URS Labs provides inspection through qualified engineers using advanced equipment, covering hospitals, fertility centres, pharmaceutical plants, data centres and laboratories.
Explore our Clean Room Inspection Services or contact us to schedule your inspection.