As with any controversial subject there are people with many different views on the subject. Some people believe that WiFi is dangerous and should be avoided, some people think that WiFi might be dangerous, and some people think that there is no way that WiFi is dangerous.
One reason that some people think WiFi is dangerous is because it emits radiation. However as you can see from the image below some types of radiation are dangerous and other types are not. The radiation types go from not dangerous to more and more dangerous as they move to the right and go from long wavelengths to short wavelenghts. That is why it is important to control your exposure to sunlight and x-rays.
These forms of radiation can be separated into ionizing radiation and non-ionizing radiation. Ionizing radiation is the type of radiation that is considered dangerous and it includes Gamma-rays, x-rays and high amounts of ultraviolet light on the high end of the ultra-violet spectrum. Non-ionizing radiation is all the other types of radiation shown in the picture below and is considered to not be dangerous.
In the picture below Wi-Fi is a little to the left of micro-waves on the spectrum. This makes it non-ionizing radiation that is not dangerous. In fact the World Health Organization very clearly states that there is no health risk from forms of long wavelength radiation.
I personally think that Wi-Fi is not dangerous unless new data shows up in the future to prove otherwise. I think that people are worried about it because the word radiation makes people nervous. I also think that people worry about Wi-Fi because it is a new technology to some people because it was invented in 1991. Just like how many people used to think that Micro-waves were dangerous.