Zone of sweet air

Zone of sweet air was an abjuration spell that protected a large area from unhealthy vapors.

Effects
All natural and magical (e.g., stinking cloud) poisonous or otherwise damaging gasses are blocked by this spell, except those from dragon breath. Fresh air could get through without hindrance. The barrier was invisible to the naked eye and only prevented the entry of noxious vapors. If any fumes were present when the spell was cast, or created inside the area of protection, they were unaffected. However, the duration of such spells as stinking cloud was cut in half by this spell.

Components
In addition to verbal and somatic components, this spell required the priest's holy symbol or divine focus, a strand of spider silk, and a silk handkerchief.