Yea 30m-50m should be good enough for me.
I have a twin uncles.
One live next to a HTC, another does not.
Both have a similar healthy lifestyle - don't smoke, don't drink etc.
The one uncle that doesn't live hear a HTC passed away 10 years ago from cancer.
The uncle that live near at HTC is still alive and healthy today. He has live in the same house under HTC for more than 30 years.
So I personally think living 30m-50m away from HTC doesn't affect ones health.
Just my opinion.