Re: things that will trigger a seizure
By your posting I'm wondering if it is vibrations that your body experiences that cause this. If you bicycle at all that could be a comparative (being non electric) to see. Or horseback riding. If other events that are non electric cause similar effects (vibrations).
It could be related to a nerve having pressure on it. The lines above would prove or disprove that theory.
An automobile's motor (most anyway) are not heavially generating emf fields. The generator (alternator) is the primary component that does. Any stereo speaker/amplifer would have an effect **IF** that is whats causing your problems.
However, at the same time, one would think household components such as the fridge, freezer, television, computer components would also be potential issues for you (magnets, motors, compressors, and larger transformers in those devices).