In rec.radio.shortwave Frank Dresser wrote:

Right, but often times there are a large number of people living in high
rise buildings near the FM antenna. It's conceivable there are more people
living in a high power FM radiation area than a high power AM radiation
area.

And the government exposure limits are more stringent at the FM
frequencies (30 to 300 MHz).

See:
http://www-training.llnl.gov/wbt/hc/...Standards.html

Art N2AH