Id be concerned as well. I wrote my public library about their strong wifi signal but I was ignored. That was years ago. I think we really have to awaken the activist in all of us. I myself am tired of complaining behind closed doors because it doesnt get anything done.
best advice is just don't bother using their service. contact someone who works there and send them peer reviewed articles on how wifi can be dangerous. one decent paper was written by Martin Pall "wifi an important threat to human health" it was included in a reputable environmental research journal.
https://www.researchgate.net/publication/323998588_Wi-Fi_is_an_important_threat_to_human_health