Valid questions and concerns. We have also wrestled with the long term effects of cell towers.

I agree that there is no definitive long term info out there and because of that, we have declined to install it in our co-op. For us, it would be like taking blood money at this time.

I'm no expert by any means, but I wonder how much 'radiation' would penetrate downward as opposed to outward from the building, thinking I would feel better under it than across the street from it.

I *am* an engineer, but unfortunately not with the specialties you are looking for. :-) The reason we might notice a proliferation of cellphone towers is not because the Deep State (or your conspiracy group du jour) is trying to exercise mind control by pumping more radiation into our frail physiques, but the opposite. GSM cellphones, the current and almost universal technology, uses less energy than CDMA cellphones. Thus you need more towers for the same coverage area.

GSM is much more directional than CDMA, and JG is correct that as much energy as possible is beamed horizontally. Verizon, AT&T and the like don't obtain any revenue by turning an apartment building into a giant microwave oven. The antennas are aimed, and I would bet there is shielding at the base of the antenna to prevent any leaks into the building.

We're constantly bombarded by radiation from many sources. Cosmic radiation, solar radiation, CT scans, dental X-rays, etc. We've been exposed to all sorts of radiation for so long that the Zombie Apocolypse would have occurred long before now.

But don't believe me. Here's a link to a July, 2019 article in the NY Times about this very topic https://www.nytimes.com/2019/07/16/science/5g-cellphones-wireless-cancer.html . Another good website for debunking conspiracies, myths, urban legends and such is snopes.com

Anything new and not easily understood will frighten segments of the population. So let's look on the brighter side. 5G radiation irradiates and kills the coronavirus. How about that for a benefit!! Prove me wrong! <chuckling>

That all sounds great, but the issue I have is that a cell carrier performed an RF test on our rooftop and within the penthouse areas and found that the radiation bleed is more than 10X the permissible or regulatory limits for safety. Their solution? If they place signs inside and barriers outside, it somehow becomes legal.
Sorry, this has nothing to do with conspiracy, its blatant greed and should be criminal to permit anything over any reasonable (whatever that is) limits. There is no denying that RF of all types are harmful to the human body (which is a virtual electromagnetic antenna). 5G spectrum have been used and weaponized by the military for years.
but that, along with the deep state theories aside... Q
BTW - whos checking the fact checkers? Snopes is soros funded!
So the original posted question was placed as an inquiry as to how to best limit liability, exposure and to see what others who have sites are doing in regard to this,,, I am still seeking someone to create a baseline RF safety report independent of the carrier.