The Nasosphere is a distinct atmospheric layer that contains large amounts of Nastium Oxide (between 5% and 70%) in the form of gas, dust or vapour. The Nastium Oxide in this layer gives a blue-green colour (or variations between green and blue) to planets with a Nasosphere. Examples of planets with a distinct Nasosphere include Mediosa, Teros, Stabilowobelia and Dinostoria, along with many others.
Though Nastium Oxide is mildly toxic (not fatal) to humans, the Nasosphere poses little threat as it is usually outside of the inner atmosphere of the planet. Some Nastium Oxides in rain may can cause minor trouble as they contaminate water sources, but these usually mutate into their less dangerous forms by the time they are consumed, or crystalize quickly after deposition.