As altitude increases, the available amount of oxygen to sustain mental and physical alertness decreases with the overall air pressure, though the relative percentage of oxygen in air, at about 21%, remains practically unchanged up to 21,000 metres (70,000 ft).
  State legislators in Texas (both representatives and senators) make a salary of $7,200 per year.
As of 2013, Senators and Representatives earn exactly the same amount per year, which is $174,000. In the Senate and House the majority and minority party leader is paid $193.