A redetermination of the isotopic composition of atmospheric neon gave abundance ratios 20Ne/22Ne = 9.80 ± 0.08 and 20Ne/21Ne = 338.0 ± 2 .5 , corresponding to percentage abundances of 90.50 ± 0.07 , 0.268 ±0.002 and 9.23 ±0.07 for 20Ne, 21Ne and 22Ne, respectively. These abundances correspond to an atomic weight of 20.179 ± 0.002 for atmospheric neon.