They cause health problems if you have VERY long term VERY close exposure to them, Like 1 foot or less, It's why people who install them have to wear protective clothing, The technician who installed one near my work was wearing a full radiation suit but again he does maintenance on multiple masts per day and exposure over the long term does cause health problems, This is why the masts are usually very high up so they pose no danger to the general public.
There may be some workers out there who choose to wear a full suit, but a hazmat suit cannot offer any form of protection against electromagnetic radiation (Even if there were a risk/the radiation was ionising, there is no hazmat suit capable of blocking ionizing radiation), and in fact this claim that workers *need* to wear suits has been roundly disputed by and disproven.
https://www.snopes.com/fact-check/hazmat-suits-5g-equipment/
Also worth noting, that if there ever was a real risk from non-ionising radiation, it would be roughly at the same level of the risks from vegetable oil and talcum powder, while even then 5G antenna's are
significantly less powerful than 4G or earlier masts & antennas as far as their power output (And therefore radiation output).
It's also false that these have to be placed far away from people, with modern technologies of 4G and 5G that have lower power/penetration, often hundreds of antennas could be fitted in the nooks and crannies of a built up city centre. Placing them higher is purely so you get better range/signal. The large tall masts are mostly for covering more rural areas with shorter buildings only, or for offering older technologies, nowadays.
If there were a risk from antenna's, there would be an equal risk from your phone, since the communication is two way and signal strength needed of both your phone's antenna and a network antenna would roughly match at best anyway.
For reference, this is what an urban microcell antenna of modern 3G and onwards tech can look like. These are for upto about a 2KM area, but modern antennas can be fitted for covering areas as small as a few hundred meters per antenna (picocells) in city centres, esp under bridges or between buildings or whatever.