Since my vera has been leaving me in peace for some time now my interest has turned to some research on the health impact of smart homes related to the increased RF emissions.
My setup has a variety of devices and a quick search online can lead to discovering that a lot of our devices are running in the 2.4GHz spectrum because… it is unregulated. Microwaves run at 2.45GHz for a reason… and it is because it is very effective at exciting water molecules. Without trying to paraphrase articles I have read, the conclusion I have come to has been that both 900MHz and 2.4GHz are most harmful to health and likely everything in between as well. My physics background also tells me that lower frequency propagate to longer ranges at the same power and that higher frequency can carry higher bandwidth. 2.4GHz unfortunately is a completely saturated spectrum with so many devices and protocols screaming on top of each other causing poor signal quality/interference.
I went around my house with a 2.4GHz spectrum analyzer and an EMF meter and these are my findings (note the units):
Highest emission devices at minimum distance:
Cordless DECT phones: If not on, they emit 2-5mW/m2, when on, the phone switches to 100W/m2. The base station of the phone hovers around 60W/m2 all the time. This is incredible.
Wifi Smart plugs: I have a number of these based and they are horrible reaching over 200mW/m2 almost as high as my UBNT unifi APs.
The Sonosnet system is also horrible emitting a very large spectrum with high power at 200mW/m2 when not playing and going up to 1W/m2 when playing. I am now trying to disable sonosnet so it can just use my wifi network.
I have a number of other wifi devices running on 2.4GHz like the filters and vacuum robots and none goes higher than 20mW/m2
I have all of my amazon echo devices run on 5GHz and their signal range is short.
Zigbee devices have very low and narrow spectrum pulse. They are generally relatively low energy and low range. and I found them to never emit more than 4mW/m2. (the aeotec HEM is constantly transmitting) and generally within noise of the emission from the 60Hz AC power.
Zwave devices carry lower energy due to lower frequency and power but have a higher signal range/power ratio. I found none exceeding 10mW/m2 either. They actually pulse going from 0-20mW
This is the advantage of mesh: using low power over short distances reducing interference with one another and with anyone else (i.e,. neighbors)
The lowest point in the house is at 200uW/m2 and the normal far away from any device baseline is 1 to 2mW/m2
Conclusion for your smart home: avoid wifi whenever you can especially at 2.4GHz. It is overkill for bandwidth, noise and power consumption which as I am finding out also contributes or cause autism in children, cancer, Alzheimer, etc… Another good reason to get rid of nest, ecobee, Google home, MyQ, Skybell, Ring and replace them with zwave/zigbee whenever we can and at least get 5GHz for devices requiring higher bandwidth than what zwave and zigbee can offer.