cosmic background

i am curious about measurements of the background radiation in the universe, and maybe how em signal levels compare to that.

This is one of the most essential questions to put forward.
We live in a totally unnatural world here on earth at the moment.
Apart from natural radio-activity locally and a strong static magnetic field ( the latter being not really radiation anyway ), i guess on the whole the radiation levels caused by technophile "progress" or modern "civilization" are at least in the order of a million times stronger than the background radiation from the planet itself and from the universe.
But it's getting worse, much worse : we and other living creatures over here are not evolutionarily adjusted to these funny new frequencies.
And it is even worse : these man-made frequencies often do not have smooth analogue wave-forms and actually may merely consist of digital pulsed spikes that lack any sort of harmony.
For those who search for examples of stupidity, just look for anything humans call "smart".

Sunlight is radiation too of course, it's likely the strongest and fortunatedly a nourishing and healthy form ( if not overdosed, but even water will kill us when we drink too much too fast ... ).
Lighting also creates frequencies, mostly in the lower kHz range.
As a measurable influence should the impact of sunspot activity probably be worth mentioning as well.
Then let's not forget about the Schumann resonance at 7.83 Hz plus its harmonics, with a strength of 0.22 to 1.1 mV/m, or about -90 dBm to -76 dBm , the latter conversion according to
http://www.aaronia.de/grundlagen/grenzwerte/umrechnung-von-masseinheiten/#c120 
I always simply use these tables, being incapable of converting the values properly.
The biological emf within our bodies is very weak, so one can expect some serious interference by frequencies from the outside, even more if the protective layer around the nerves is damaged, for example as a result of lyme disease.
A radiant aura ( body-awareness and raw food may help here ), low levels of toxins ( quicksilver etc. ), health in general of course, and as little exposure to technocrazy emfs as possible, could be keys to handling a civilized environment.