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The New Horizons spacecraft's nominal trajectory crosses the planet'ssatellite plane at $\sim 10,000\ \rm{km}$ from the barycenter, between theorbits of Pluto and Charon. I have investigated the risk to the spacecraftbased on observational limits of rings and dust within this region, assumingvarious particle size distributions. The best limits are placed by 2011 and2012 HST observations, which significantly improve on the limits from stellaroccultations, although they do not go as close to the planet. From the HST dataand assuming a `reasonable worst case' for the size distribution, we place alimit of $N < 20$ damaging impacts by grains of radius $> 0.2\ \textrm{mm}$onto the spacecraft during the encounter. The number of hits is $\approx$200$\times$ above the NH mission requirement, and $\approx$ $2000\times$ abovethe mission's desired level. Stellar occultations remain valuable because theyare able to measure $N$ closer to the Pluto surface than direct imaging,although with a sensitivity limit several orders of magnitude higher than thatfrom HST imaging. Neither HST nor occultations are sensitive enough to placelimits on $N$ at or below the mission requirements.

New Horizons Ring Collision Hazard: Constraints from Earth-based Observations