Which would kill you first if you were kicked out of an air lock naked on Mars Remember a habitat on Mars would not be kept at 1 standard Earth atmosphere. It would be more likely at the pressure of a airliner at 30,000 feet which is the air pressure at about 7000 feet.
Freeze to death
Blood boil
Asphyxiate.
Brain hemorrhage/stroke.
Remember that there are no Earth habitats on Mars, and that the surface conditions won't support anything other than microbial life -- no humanoids, no insects, none of Arthur C. Clarke's banyan trees.
The pressure is equivalent to Earth at 100,000 feet. The atmosphere is predominantly carbon dioxide, but at that pressure it doesn’t matter. Your blood boils as you asphyxiate, without a pressure suit.