Air sampling for 10 minutes for 1000 liters of air is a common practice based on USP Chapter <1116>, which addresses microbiological control and monitoring of aseptic environments. This standard outlines guidelines for assessing the microbiological quality of air in controlled environments.
The 10-minute sampling duration ensures an adequate volume of air is tested to detect the presence of viable particles (microbes), considering the air flow rate of the sampler. For instance, an air sampler operating at 100 liters per minute would collect 1000 liters in 10 minutes. This volume allows for a representative sample of airborne contamination in cleanrooms or controlled environments.
Mechanical air samplers have a limitation: they can only test a small amount of air at once. When the air in a controlled environment, like a cleanroom, has very low levels of contamination, it’s important to test a large volume of air at least 1 cubic meter (1000 liters) to detect any microbes effectively.
𝐅𝐨𝐫 𝐄𝐱𝐚𝐦𝐩𝐥𝐞: a common type of air sampler can process 80 liters of air per minute. To test 1 cubic meter, which is 1000 liters, you would need to run the sampler for about 15 minutes. In some cases, you might need to test for even longer to get a better idea of air quality.
Testing for long periods or with higher air volumes can disturb the airflow in critical areas, which might cause problems.
To avoid this, technicians might use remote sampling systems, which allow testing from a distance, reducing the risk of disrupting the airflow. But when using these remote systems, it’s important to ensure that the extra equipment (like tubing) doesn’t affect the ability of the sampler to detect low levels of contamination.