As an expert in the field of astrobiology and planetary atmospheres, I can provide you with a detailed answer to your question. "Mars" does indeed have an atmosphere, but it is significantly different from Earth's. The Martian atmosphere is incredibly thin, being approximately 100 times less dense than Earth's. This low density is due to the fact that Mars has a much weaker gravitational pull, which makes it difficult for the planet to retain a thick atmosphere. The composition of the Martian atmosphere is also quite distinct. It is composed mostly of carbon dioxide, which makes up about 95% of the atmosphere, with the remaining being a mix of other gases such as argon, nitrogen, and traces of oxygen and water vapor. The percentage of oxygen in the Martian atmosphere is extremely low, far below the level required to support human life. Given these conditions, humans cannot breathe the air on Mars. The lack of sufficient oxygen and the overall thinness of the atmosphere would make it impossible for an unprotected human to survive. An astronaut on Mars would require a spacesuit with a life support system that provides oxygen to breathe and protects from the harsh conditions. In summary, while Mars has an atmosphere, it is not breathable by humans. The thin atmosphere and the low oxygen levels necessitate the use of specialized equipment for any human presence on the Martian surface. read more >>

Mars does have an atmosphere, but it is about 100 times thinner than Earth's atmosphere and it has very little oxygen. The atmosphere on Mars is made up of mainly carbon dioxide. An astronaut on Mars would not be able to breathe the Martian air and would need a spacesuit with oxygen to work outdoors.read more >>