[DB 1506 (8); OAB 35] It is claimed that the atmosphere's level of Helium-4 (which is created by radioactive decay) should be much higher if radioactive decay has been going on in the Earth's crust for 4.6 Gyr. The calculation behind this claim assumes that helium escapes by a simple thermal-gravitational process, as it does from planets without large atmospheres. In reality, the Earth's magnetic field causes it to give off a stream of particles from the poles, in a process identical to the formation of the solar wind. This "polar wind" carries atmospheric particles away from the Earth, and is primarily responsible for removing Helium-4 from the atmosphere at a faster rate than gravitational escape alone would do (see page 8 of D.M. Hunten, Icarus, v.85, pp.1-20 (1990)). Furthermore, if one truly wanted to use noble gas abundances to determine a date for Earth's atmosphere, a much better method would be to use Argon-40 rather than Helium-4. Argon-40 is also created by radioactive decay, but because it is much heavier than Helium-4, it does not escape from the atmosphere at any appreciable rate. H.A. Shillibeer and R.D. Russell attempted to date the atmosphere precisely this way (Geochimica et Cosmochimica Acta, v.8, pp.16-21 (1955)). Although this is not the most accurate dating method, due to uncertainties in the rate at which Argon-40 enters the atmosphere and other outstanding questions, Shillibeer and Russell did arrive at a date in generally good agreement with with the accepted age of the Earth. In conclusion, the polar wind emanating from Earth's upper atmosphere is the main reason that there is less Helium-4 in the atmosphere than would otherwise be expected, but from looking at heavier radiogenic gases that do not escape gravitationally, it is clear that there is no discrepency between atmospheric abundances and the age of the Earth.