I dont tolerate led or lcd tvs or monitors. Only a tiny bit, of course depending on size, lightstrength and distance. Even Smartphones and tablets. What detector do I need to measure the bad radiation that these Things emits?
You could try a dirty electricity meter. Some TVs make more dirty electricity than others.
But this only tells you how much EMF is going in the wiring, not coming out of the TV.
Generally not a lot that you can measure. E fields can be high unless a coax cable is hooked up which will ground the TV. Most TVs have 2 prong, no ground. So the coax can ground it, if it's a grounded coax cable which they all should be if installed properly.
M fields are pretty low also, and RF fields will be in the range that can't be easily measured. An AM/Shortwave radio works best, and will buzz loudly when closer to the TV.
There is also the ESmog Spion meter that can measure light emissions. I don't think it's the light coming out that causes problems, unless it's flickering then maybe it can cause headaches, but not skin burning. For me face burning is EMF related, not light.
There are USB laptop screens that are supposed to be better, but I haven't tried any. It plugs in the USB only, not in the power outlet. If you use that with a laptop on batteries it should be better, but you also have to ground the laptop. There are USB ground cables that you can use to ground any laptop.
I find laptops that cause minimal heat and don't have a fan running most of the time are best. More heat and fan running will emit more EMF.
Just buy a very low wattage screen/ tablet with no hard drive or fan. 12vDC motors are the dirtiest things about for magnetic and FRI pollutions. Sellers should have to put the wattage of devices on the spec. My monitor is less than 10 watts but they don't make them that energy efficient any more cos they think bigger and hotter is better and we cannot choose cos they don't tell us this info..Cheap AM radios are best for showing emissions. Never be within the range you can pick up as a fuzzed mess. Use wired every thing with ferrite chokes. I only use 12vDC from a linear power supply. Avoid 5v USB as this is harder to get clean because of pulsed chipped transformers power supplies. Who decided on 5 volts? Why not 6? Sadly most USB devices cannot handle 6 volts.
All you need is a radio to see the difference that chokes make! Foiling your wires will cut out electric field. If you are using a 12vDC linear power supply you don't get an electric field". You do get dirt from your devices. You can stop some of that with ferrite chokes. Put at device end to start. This will stop your wire broadcasting. Attach more at 10P each until you are comfortable!
You say " glass fibre around the power supply helps a lot". What is this magic glass fiber please? I have wrapped ali foil around switching power supplies ( very dirty).
A linear power supply will not make any thing but 12vDC so needs no cleaning. It will have an electric field going to it and a mag field at the box but after that and near to you nothing but clean 12vDC. Use a shielded cable to the box if you need to. I run my TV and computer and lights of one.