Oxygen level card restriction on Terraforming Mars
It is &quot;X% level or above&quot;.
The rulebook gives a few examples of cards, along with the restrictions of when they can be played. Card &quot;D&quot; in the example list is Livestock, which shows &quot;9% oxygen as a requirement&quot;, and the rules state:

To play card D, the oxygen level must be 9% or higher. You also need to have plant production, since the card requires you to decrease your plant production.

(Emphasis mine).
Card E is Shuttles, and it shows the same requirement icon, needing 5% oxygen. The rules state:

Card E requires 5% oxygen and energy production.

So the rules consider &quot;requires x% oxygen&quot; to be interchangeable with &quot;requires x% oxygen or more&quot;.