In the novel *Dandelion Slap*, the second book of the *Gaia's Wasp* trilogy,
a government official claimed our atmosphere shields us like three feet of solid lead. Was he right?

Let's consider one square centimeter of dirt, about half the size of a dime. That dirt supports a skinny column of air that reaches all the way up to space, roughly a hundred miles. How tall would the column be, if the air were replaced by the same mass of Lead?

Sea-level air pressure, which is just the weight of our atmosphere, is 14 lbs per square inch. This is
2.2*lbs*/*cm*^{2} = 1*kg*/*cm*^{2}.

In other words, each square centimeter of Earth support a skinny column of air that weighs one kilogram. Suppose that column of air was replaced by a column of Lead with the same weight. How tall would it be?

Lead has a density of 11*g*/*cm*^{3}, so a one-kilogram lead column
must contain 1,000 *g* / (11 *g*/*cm*^{3})
= 91 *cm*^{3}.
If its cross-sectional area is 1 *cm*^{2}, then its height must be 91 *cm*, or 36 inches.

In other words, we live under the gaseous equivalent of a three-foot-thick lead slab.

Three feet of Lead is pretty impressive. No wonder it blocks cosmic rays. Would it protect us from the boxcar full of gold?

No.