Wireless safety advocates have called for more studies on the effects of the exposure, and one group is trying to stop the rollout of 5G networks in Chicago’s neighborhoods. Verizon and Sprint turned on their 5G networks in parts of Chicago earlier this year, putting the city among the first in the nation with access to 5G. AT&T plans to turn on parts of its Chicago network later this year, and T-Mobile is aiming for 2020.