If the ESD continues to happen time and again, it may start to disrupt equipment operation. If there is not a lot of testing in place, circuit boards may leave your plant. They could then come back because there are problems. You want to pay attention to each and every ESD event. This allows you to document problems with the overall amount of electrostatic discharge in the air.
The ESD can occur because of human contact, clothing, and much more. Employees may wear electrostatic wrist straps. This may not be enough. It may involve placing synthetic materials near electronic equipment, moving quickly near electronic equipment, and many other scenarios. You cannot control everything in such an environment and therefore you have to control the static electricity that is present within the air.