Earth: 2.5x1019 mol/cm3 (STP, 1 atm)
Moon: ≈104 mol/cm3 day and ≈ 2x105 mol/cm3 night or approx. 10-14 of that found on Earth i.e. 10-14 torr.
Carrier, W.D., Olhoeft, G.R., and Mendell W. (1991). "Physical properties of the lunar surface." The Lunar Sourcebook. Heiken, V. and French, eds., Cambridge University Press, New York, Vol. 1, pp. 284 - 293.