This is the process of verifying that a cleanroom meets the required standards for its intended use. Validation and certification are usually performed by third-party agencies that conduct various tests and inspections to ensure the cleanroom’s performance, safety, and compliance1.

Some of the tests that are commonly performed during a cleanroom validation and certification are:
• Airflow or smoke pattern test: This test uses a smoke generator to visualize the airflow direction and velocity in the cleanroom. It helps to identify any areas of turbulence, stagnation, or leakage that may compromise the cleanliness level 2 
• Particle count test: This test measures the number and size of airborne particles in the cleanroom using a particle counter device. It helps to determine the cleanroom class according to the ISO 14644-1 or FS 209E standards 3
• HEPA filter integrity test: This test checks the efficiency and leakage of the HEPA filters that provide filtered air to the cleanroom. It uses an aerosol photometer to scan the filter surface and detect any pinholes, cracks, or defects that may allow particles to pass through1 
• Air pressure differential test: This test measures the difference in air pressure between the cleanroom and the surrounding areas using a manometer. It helps to ensure that the cleanroom is maintained at a positive pressure to prevent the ingress of contaminants from outside1
• Temperature and humidity test: This test measures the temperature and relative humidity in the cleanroom using a thermometer and a hygrometer. It helps to ensure that the cleanroom conditions are suitable for the product or process that is carried out inside1

These are some of the main tests that are involved in a cleanroom validation and certification. There may be other tests depending on the specific requirements of the cleanroom application, such as sound and lighting, microbial sampling, recovery time, etc.