A Brief Overview of the Problem of Unintended/Incidental EMC

On the other hand, unintended/incidental EMC compliance is less straightforward and most likely will be one of your biggest product verification headaches. It is usually not well controlled and sometimes not even thought about during the design and test stages. Unintended emissions are not part of the design; they are spuriously generated nuisances as a result of a design - mostly when compliance is an afterthought. The basic problem is depicted in the figure below.

A source of an unintended effect (emissions) can disrupt a nearby product (or biological, fuel or ordinance entity). Since the emissions are spurious and not by design, they're effect is more difficult to predict during the design of a device, so elimination or reduction of the disruption is more difficult.
The device or system being designed also must be protected from external emissions and static pollution.

Medical and military products are heavily regulated for susceptibility (immunity) failures, since life threatening and national security issues can occur. The European Union, which may require the CE mark, is tough on product susceptibility too.

Note that EMI (ElectroMagnetic Interference) and RFI (Radio Frequency Interference) are general terms used to describe unintended energy emitted from a product.

So… What Do You Need to Know?

Not the trees, but the forest… You should be informed enough to ensure that your design team has the skills and knowledge to achieve proper EMC compliance.