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.
The annual salary of a rank-and-file Representative in 2011 is $174,000. The Speaker gets $223,500 and the two party leaders get $193,400. The current salary (2010) for rank-and-file members of the House and Senate is $174,000 per year.