Protect Atmosphere
(Abjuration, Alteration)

Range:  10 feet per level
Components:  V, S, M
Duration:  1 week per level (or 1 turn per level)
Casting Time:  5 rounds per ton (or 1 round per foot)
Area of Effect:  One ship's atmosphere (or one 1-foot radius per level sphere for one creature per level)
Saving Throw:  None

This spell exists in two versions: one ship-bound version and one person-bound version.
The ship-bound version causes the atmosphere of a ship to be protected from the effects of external sources of pollution. Thus, it does not allow the atmosphere of two ships to mingle that touched each other with their air envelopes (even if that would be desired). This also causes the phlogiston to stay out of the area of effect. Thus, it would be possible to light fires within the phlogiston or to cast fire-based spells within the area of effect without the atmosphere to explode. It is possible to open this shell around a ship if the caster desires such an opening. This opening of the shell takes one round per ton of ship to be opened. Thus, it would still be possible to exchange air through the air envelopes. This shell does not offer protection from other effects with the exception of gaseous spells that are cast from the outside of the air envelope of the ship: they are completely negated if they are cast across the border of the shell. Even if two ships touch each other their air envelopes still do not mingle; thus, it would not be possible to cast a cloud kill from one ship to the other if the caster is not on the other ship, respectively.
The material component for this version of the spell is a perfect model of the ship in a 1:1000 size including any rooms to be made. This model is lit and burned within a sealed bottle which contains pure elemental air from the plane of air. The bottle has to be large enough to contain the unshrunk model of the ship. The bottle has to be sealed with a single diamond carved into a stopper.
The person-bound version allows the affected creatures to enter any area which contains either dangerous gases or no gas at all without negative effects. The effects are completely negated even if cast inside the sphere around each creature. Thus, it protects the creature inside the sphere from any gas attacks, even those of an incredibly high wind. The notes within parentheses pertain to this version of the spell.
The material component for this spell is one hollow, perfectly round sphere of blown glass for each creature to be affected.

