No, it's not. It's just a clickbait article you have seen.
There are numerous articles floating around the Facebook newsfeed about how dangerous wifi is to someone's health. Artikulo Health News even described Wifi as a "silent killer" that can be the "cause of various health issues."
Their source is another blog that also came from a clickbait article.
According to HowToGeek, a website specializing on anything "geeky" like technology, these claims are "ridiculous."
"There are a staggering number of articles on the Internet trumpeting the dangers of “Wi-Fi radiation” and how risky it is to your health. Don’t worry: it’s a bunch of nonsense," their article said.
He said the term "radiation" should not always be used as a scare tactic.
"Radiation is also the thing that bathes the world in warm sunlight and makes life on Earth possible. Radiation is also the reason we can turn on a radio and hear music without wires. Radiation is how we change the channels on our television (and for anyone getting their TV fix via over-the-air channels or satellite TV, how the programming gets delivered to their home in the first place)," the article said.
In summary: Long wavelengths? People should not worry. Enjoy your wifi, radio station, and delicious microwaved food. Enjoy using your wifi.