How safe is radar ?

Non-ionizing radiation protection is about keeping the intensity at occupied positions below certain thresholds. You can do that by controlling the output power and direction, prohibiting personnel from certain areas, or shielding certain areas.

For microwave energies, you shield with high-conductivity materials, not high-density materials. Lead shielding is for keV to MeV energies.

No, it doesn't work like that. Even considering only EM (photons), different energy ranges have hugely different effects. Hence, we have very different regulatory limits for each type.

Example:

People can tolerate an intensity of 1000 W/m2 more-or-less indefinitely with no ill effects in the visible (1 eV) band. We are biologically adapted to tolerate this very well as it is part of our regular outdoor environment.

That same intensity in the microwave communication bands (say 10 ueV, so 100,000 times more photons each at 1/100,000 the energy) is a hundred times more than generally accepted exposure limits. The problem here is tissue heating as the water in our cells tends to absorb these energies very well; if the heating outpaces our internal cooling systems, there is a risk of hyperthermia.

That same intensity at 50 eV (1/50 as many photons, each of which is 50 times more energetic) will give you serious sunburn in minutes. The problem here is that these photons are energetic enough to strip electrons from their atoms, thereby causing chemical reactions that damage key components of your skin cells.

That same intensity at 1 MeV (1/1,000,000 as many photons, each of which is 1,000,000 times more energetic) will, in half a minute, leave you with fatal radiation poisoning. As with the previous example, these photons are knocking electrons out of their atoms, except that at 1 MeV they can reach your internal organs instead of just your skin.

There is a lot more to this problem than "AAAAAARADIATION!". Radiation protection is a well-understood science grounded in sound physical principles and very conservative estimates of risk. Its remaining unanswered questions are about teasing extremely weak epidemiological statistics out of very loosely correlated data concerning the long-term biological effects of repeated / continuous exposure to extremely low intensities in various energy ranges. The fundamentals, along with just about everything regarding higher-than-background intensities, have been well known for many years.

 

Yep HERO from escorts have caused activation of ordinance. And standing in the beam of certain radars will cook you. FWIW though, the US Navy has more injuries caused by the rotating units than the beam itself.

 

Radar or microwave energy can be stopped by a wire mesh. You do not need lead or sheet metal. The wavelength is so small that a 1.5 mm. mesh can absorb the energy by not allowing the electrical wave to pass through. FRP boats radar base uses grounded aluminum or ss wire mesh protecting its crew and the electronics below.

Microwave oven glass door is lined with wire mesh so you can see what's cooking without being exposed to the microwave energy.

Big sattelite (C band) dish reflectors are made of wire mesh supported by frames. The smaller sattelite dishes operating on the higher frequency band can be wire mesh but it is more economical to stamp it out of sheet metal.