Earth's is 101,000 Pa dropping to 30,000 on top of mount Everest. Mars's mean surface pressure is around 600 pascals which is below waters triple point which prevents water from forming regardless of temperature. http://en.wikipedia.org/wiki/Triple_point Still that's close and in some creators the pressure increases high enough so it's possible for water to form.
Unfortunately, on top of that what makes the atmosphere truly deadly is a lack of Nitrogen one of the primary building blocks for organic chemistry.
Unfortunately, on top of that what makes the atmosphere truly deadly is a lack of Nitrogen one of the primary building blocks for organic chemistry.