“The voluntary exposure of the brain to microwaves from WiFi and hand-held mobile phones is the largest human biological experiment ever. There is clear evidence that this radiation causes leakage of the brain’s blood-brain barrier with adverse effects on brain function.” ~ Neurologist, Professor Salford, MD, Lund University
The great reduction in size & costs of electronic components since the 1980s and the great increase in their ability to oscillate at ever higher frequencies has opened up increasingly greater amounts of radio spectrum - for every conceivable use. Wireless use has mushroomed ever increasingly for cell phones and WiFi - not only at work - but at home & everywhere else. The greatest increase in wireless use has been in the use of microwave frequencies; those at or somewhat above the UHF-TV band.
"Microwaves", for this overview, will include frequencies from 500 MHz up to 3000 MHz (or 3 GHz). Such wavelengths lend themselves well for uses where compactness is desirable; in rooms where their transmitters are near people and for portable uses near the body. Small wonder, then, that occurrence of some diseases has increased alarmingly since the 1990s. Studies show correlation between cellular use and specific, previously rare brain cancers. Autism has also spiked markedly. A general overview pulls together such observations and more. 
It has been known that radio frequencies and microwaves affect living things. The U.S. Navy knew of such effects when they began working on radar in the 1930s. 
1 THE WIRELESS ELEPHANT IN THE ROOM, Camilla Rees, February 5, 2017