NAG would be fairly appealing if not for the presence of naturally-occuring toxic compounds in its atmosphere.  The toxins are neutralized by Nag's abundant plant life, but are continously released by native microbes in the soil.  Human society proceeds as normal inside sealed buildings, but not everyone has the luxury of living there.  A unique feature of Naggite society is its progressive caste system.  The lowest-level citizens do all outdoor work like farming, where they must wear helmets and portable breathing apparatus at all times.  All of their children, however, are entitled to move up to the next caste, which labors indoors or transports goods across the globe.  The children of this caste then become managers and administrators.  What becomes of the top-tier's children?  They all join the lowest caste to start over again.  This circle of life is part of the Naggite religion, and no one can advance in caste through any of their own efforts.