NP Atmospheres

Atmosphere Classifications
The Coalition standard for rating planetary atmospheric conditions on planets or other material bodies of sufficient mass for scientific classification or even simple travel advisories.

Type I (Breathable)
A type I atmosphere has a proper mixture of oxygen, nitrogen and other gases so that humans and comparable species can breathe it unassisted. These atmospheres may have contaminants that over the long term have a detrimental effect. Planets with a type I atmosphere will have life or at least had life recently.

Type || (Breath Mask Suggested)
Type II atmospheres can support life without use of a breath mask, but either due to too much or too little atmospheric pressure or oxygen, or unusual gases or contaminants, it is recommended that a breath mask be worn. Without a breath mask, detrimental effects, such as slowed reactions, reduced brain activity, poisoning, or a myriad of other effects can begin to occur within just a few hours of exposure. Many alien species can comfortably breathe type II atmospheres without having to resort to breath masks. Planets with a type II atmosphere will have life or at least had life recently.

Type III (Breath Mask Required)
Type III atmospheres are unbreathable without a breath mask, again due to a number of possible characteristics. The atmosphere could be highly poisonous, or simply not have enough oxygen to breathe. Characters without breath masks can begin to suffer detrimental effects immediately. A small number of alien species (and certainly native creatures) will be able to breathe these atmospheres unaided. Type III atmosphere planets frequently support life.

Type IV (Environment Suit Required)
Type IV atmospheres are not only poisonous, but they are so reactive that they will cause injury to persons who are exposed to it. Environment suits, spacesuits or life-support equipment is required to venture through the atmosphere, or characters will suffer burns and other grievous injuries. If the planet is frigid, a thermal suit may be necessary. These atmospheres may also be flammable or highly explosive.

None
This planet has no appreciable atmosphere and a space suit is required simply to survive on the world. Planets without an atmosphere typically have much greater temperature variations because there is no atmosphere to disperse solar energy (on the sun side) or retain heat (on the night side).