How does electromagnetic affect people in the world ?

That depends on the wavelength of the electromagnetic radiation.

-- If the waves are long, then we use them for radio, TV, and cellphones.

-- If the waves are shorter than that, then we use them for GPS in the car.

-- If the waves are shorter than that, then we use them to heat meatloaf
in the microwave oven.

-- If the waves are shorter than that, then they warm us and they
make our plants grow ... like the ones we eat.

-- If the waves are shorter than that, then our eyes use them to see with.

-- If the waves are shorter than that, then they tan our skin.

-- If the waves are shorter than that, then they can cause cancer on
our skin.

-- If the waves are shorter than that, then they can cause cancer and
other diseases in places inside our body.