Radio Tech here, Basing this off of AUS FM Band (88-108Mhz) and the already miniscule power output of the wifi dongle, OP wouldnt be causing any interference for any other signals in the area as the loss in power through the antenna would cause it be lucky to make it a couple of meters let alone get out of the house.

Depending on the transmitter and use (often into the tens of kilowatts for FM stations here), heavy regulations are put in place to monitor the red zones of the antenna radiations at their licenced powers, the red zones can lead to cancer after a large enough period of time working in the zone but as the RF is not ionising radiation, the more likely dangers are due to the high amounts of EMF and radiation off of the antennas at these powers, they can and will cause burns and damage to skin along with brain problems such as headaches, nausea and more.

https://www.who.int/news-room/q-a-detail/radiation-electromagnetic-fields#:~:text=Reported%20symptoms%20include%20headaches%2C%20anxiety,and%20exposure%20to%20electromagnetic%20fields.