Stairstepping issue with volumetric lighting

Using Movable Spot Lights as head lamps for a vehicle with Volumetric Scattering Intensity set to 12.
Also using Exponential Fog with Volumetric Fog enabled.
Ray tracing is enabled.
How can I reduce or eliminate the visible ‘stairstepping’ in my lighting?

I believe its due to the sample rate. i just watched a video on this,