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.
Members in the House are called representatives. Each state receives representation in the House in proportion to the size of its population but is entitled to at least one representative. There are currently 435 representatives, a number fixed by law since 1911. The most populous state, California, currently has 53 representatives. There are seven states with only one representative: Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont and Wyoming. Each representative serves for a two-year term. There are no term limits.