At a distance of 20 pc from the purported supermassive black hole powering quasars , temperatures and densities are inferred from optical observations ( [ Osterbrock 1989 ] ) to be \sim 10 ^ { 4 } K and \sim 10 ^ { 4 } cm ^ { -3 } .
Here we present Very Long Baseline Interferometry radio observations revealing organized magnetic fields on the parsec scale in the hot plasma surrounding the quasar OQ 172 ( 1442+101 ) .
These magnetic fields rotate the plane of polarization of the radio emission coming from the core and inner jet of the quasar .
The derived rotation measure ( RM ) is 40,000 rad m ^ { -2 } in the rest frame of the quasar .
Only 10 mas ( a projected distance of 68 pc ) from the nucleus the jet absolute values of RM fall to less than 100 rad m ^ { -2 } .