Anomalous amounts of volatile elements found in the Apollo samples brought back from the moon have been traced back to our own planet's leaky atmosphere.

Good news for lunar bases? Earth's atmosphere leaks all the way out to the moon

Source: space
Source Link: https://www.space.com/astronomy/moon/good-news-for-lunar-bases-earths-atmosphere-leaks-all-the-way-out-to-the-moon