  We report on our recent detection of the transverse proximity effect of 4
foreground quasars near Q0302-003 (z=3.285) as a local hardness fluctuation in
the spectral shape of the intergalactic UV radiation field, found by
correlating the HI Ly\alpha absorption with the corresponding HeII Ly\alpha
absorption. We argue that the spectral hardness is a sensitive physical measure
to reveal the influence of quasars onto the UV background over scales of
several Mpc, and that it breaks the density degeneracy hampering the search for
the elusive transverse proximity effect. From the transverse proximity effect
on scales of several Mpc we obtain minimum quasar lifetimes of ~10-30Myr.
