I know I'm replying to my own question, but here's what I found:
OSHA has determined that the recommended maximum safe level of exposure to microwaves is 0.2 milliwatts per centimeter squared. The average intensity can be as high as 0.8 (milliwatts per centimeter squared) when the scanner is stationary. At a distance of 7 to 10 feet from the scanner, the average intensity drops to safe levels (i.e. below 0.2 mW/cm2).
Crewmembers should be briefed about the hazards of RF energy and instructed to avoid the scanner by a minimum horizontal distance of 6 feet and a vertical distance of 2 feet when the radar is operating. Crewmembers should be briefed to not remain within the hazardous area for prolonged periods.
During normal radar operation, the average exposure is reduced, because the scanner rotates and a person is exposed only when the beam sweeps past. For example, a person standing three feet away from a four-foot rotating scanner is exposed to less than 20 percent of the average radiation level of a stationary beam. Exposures to microwave radiation above the recommended safe limits are most likely to occur in the immediate vicinity of a transmitting scanner when it is stationary. When the scanner is rotating for normal radar operation, average exposure is below the recommended safe limits; even at points as close as 3 feet.
Information "borrowed" from
SailNet .