If your gaussmeter measures an H field accurately at 900 or 2.4 GHz, I want a) the model number, and b) the stock ticker symbol of the company who makes it, because they are gonna make BAZILLIONS.
Of course, no such instrument exists, and your gaussmeter is useless for such purposes. You should be using a field strength meter.
As it seems, that company - Alphalab - specializes in making test equipment for a hypochondriac.
The easiest way to measure field strength is by using a calibrated antenna and a calibrated spectrum analyzer, often with a calibrated amplifier. That's what compliance labs are using.
Also, 10 milligauss reading doesn't say anything except that the [static] magnetic field is probably 10 milligauss. To compare, a common refrigerator magnet produces 50 gauss - which is 5,000 times as much. I guess all housewives are now doomed? By the way, that 10 milligauss reading probably comes from steel screws that got magnetized in Earth's magnetic field (which is about 400 milligauss at the surface of this planet.)
But the fact is that human body, unless augmented with magnetic materials, is not sensitive to magnetic fields. That's why MRI scans are possible. It is pointless to measure something unless it is clearly understood what it is that you are measuring and what the measured field does to you.
If someone wants to be really scared, they should get a proper microwave power meter, with a small horn, and measure the leakage from their microwave oven in the kitchen. The magnetron (or klystron) there is happily producing kilowatts of power just inches from your face. The door is equipped with a mesh that is supposed to block the RF, but often there are leaks from other places. But hardly any home oven is ever checked for leaks. I had a radar detector a couple of decades ago, and I tested it on a microwave oven, and it did register the signal. Mind you, it was a simple diode in a horn... think of how much power was leaking to get to a reasonable voltage across the waveguide.