There actually is alot of evidence that WiFi is harmful.
There are now thousands of peer-reviewed scientific papers showing biological effects from RF radiofrequency microwave radiation.
There are dozens of papers that have reported genetic effects. Two recent studies have found damage to DNA and the reproductive system from WiFi.
WiFi emits levels of RF that are more than high enough to cause health issues. There is tremendous variability in radiation levels, and this can be confusing for those who haven't studied or measured it.
A router emits very high levels right next to it, as do iPads and laptops. The further away from the source, the lower the level. At 10 feet away from a router, the radiation levels are similar to having a cell tower down the street.
I have tested this extensively, and I provide the facts at: