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Papers on adverse health effects of wi-fi is in the wi-fi wiki:
https://www.reddit.com/r/Electromagnetics/comments/3zvv2q/wiki_wifi_adverse_health_effects/
There are various sources of wi-fi: router, wi-fi emitted by your laptop and other devices, some models of smart meters and internet of things. Other models of smart meters use broadband over power line which produces dirty electricity.
Manufacturers have designed new routers stronger for wi-fi to be transmitted throughout the home for the internet of things. See the wi-fi: routers wiki:
https://www.reddit.com/r/Electromagnetics/comments/5a72rw/wiki_wifi_routers/
There are several android wifi radiation apps which measure the power density of routers:
Wifi Radiation Meter app uses the Russian unit microwatts per centimeter square (uW/cm2) for the total power density of nearby routers. Wifi Radiation Meter uses nano watts per centimeter square (nW/cm2 unit for the power density of each router. Convert nano watts to microwatts. 1000 nanowatt = 1 microwatt.
Quanta Monitor by Cellraid uses microwatts per meter (uW/m2) unit. To compare them, convert one unit to the other unit. The developer is Finnish. Western Europe uses ICNIRP safety standards which is not as safe as Russia's. ICNIRP uses meter square. The ICNIRP based power density measurement uses per meter square (m2). Meter square needs to be converted to centimeter square (cm2) to compare safety standards and to compare exposures of cell phones and routers. See the safety standards wikis in /r/electromagnetics.
Download of Wifi Radiation Meter app by yannisassael.com:
https://play.google.com/store/apps/details?id=gr.ic3man.wifiradiation
WiFi Exposure Meter Free app by Sigint Solutions Ltd
https://play.google.com/store/apps/details?id=com.sigintsolutions.apps.wifihealthmeterfree