i was thinking heating with miners is not healthy, as the electronics are releasing toxic materials into the air.
As long as the temperature of the PCB is less than 300 degree, there is no problem about toxic materials.
There has been a lot of debate about this, even a desktop PC will release *some* voc's during it's lifetime. On the plus side it's been agreed that a 1500M household air filter will negate any potential exposure.