Question

explain why it is dangerous or even fatal for an electronic pacemaker to be near sources of electromagnetic waves?

Answer 1

The truth is that we are 'bathed' in electromagnetic waves all of the time. Cell phone transmissions, computers, power lines, microwaves ovens: all emit significant electromagnetic waves: some with quite tangible amounts of energy.
But while it is true that there is a theoretical danger to pacemakers, people with pacemakers live relatively normal lives: they use phones and microwave ovens, they walk under power lines, and so forth without danger.
There are special situations: like near Magnetic Imaging devices which generate very powerful magnetic fields - where a pacemaker is vulnerable. But these situations are rare. One does not often hear of 'incidental' disruptions of pacemakers.