is been blasted by KW's of ultrasound all day dangerous?
The simplest answer is - nobody knows for sure, but there are enough data points to be concerned. It doesn't exist naturally, and there's not been any equipment over the last century that consistently outputs 140dB+ in the 40 to 100 kHz range without far worse effects in the audible range swamping it, or consistent studies to isolate that effect. There are studies that show we should be concerned both with long term effects, as well as more short term ones - long term hearing damage, sub harmonic generation, heating etc - but nothing definitively proven. It would also be unethical to run those experiments on people, so basically we're in the early stages of a mass experiment in this regard where the public are the test subjects. In a sane world, this wouldn't be allowed to be tested in this manner until proven safe, rather than the situation we have now which is "prove it's dangerous and then we'll stop", where those tests are illegal as well as unethical - an unattainable burden of proof
uBeam claim to have run lots of independent 3rd party tests that prove it's safe. Except they won't release those test results or say who the third parties are. I call bullshit on this. There's enough data out there that makes it very suspicious. That they keep claiming that "99% of energy bounces off the skin" is telling, as it's not the skin that's the problem, it's the hair on it that causes the problem (loss in hair causes heating, burns, and in small animals death at high enough levels).
I put together a list of information on this topic if you want to study further:
https://liesandstartuppr.blogspot.com/2019/01/ultrasound-in-air-safety-and-regulations.html