Cities worldwide AND entire countries have taken action to ban, delay, halt, and limit 5G installation AS WELL AS issue moratoriums. There IS research that HAS determined that exposure is NOT safe.
There have also been reports of people and animals experiencing symptoms and illness after it was installed and turned on (see 1. 2, 3, 4) since 2018.
Of course, exposure to other sources of wireless radiation can cause health issues as well. In fact, last year The World Health Organization warned that high levels of Electromagnetic Radiation (aka "Electrosmog") could lead to health issues in 30% of the population.
5G opposition is about A LOT more than health and environmental risks (see 1, 2, 3). Robert F. Kennedy Jr. spoke about this yesterday at a rally in Berlin.