Breathing 0.5% carbon monoxide at a depth of 132 feet is equivalent to how much carbon monoxide at the surface?

The concept at play in this question involves understanding how pressure affects the concentration of gases, particularly in relation to diving. When at depth underwater, the pressure increases, which in turn affects the partial pressure of gases inhaled.

At 132 feet of seawater, the absolute pressure is approximately 5.0 atmospheres (4 atmospheres from the water plus 1 atmosphere from the surface). When a diver breathes in a gas mixture, the concentration of any gas expressed as a percentage at the surface is influenced by the increase in pressure at depth.

To find out the equivalent concentration at the surface, you can use the formula that relates depth and pressure. Since the pressure increases with depth, the effective concentration of a gas increases correspondingly. Specifically, if the diver is breathing a mixture that contains 0.5% carbon monoxide at 132 feet (where the pressure is roughly five times that of the surface), the actual partial pressure of carbon monoxide would be 0.5% multiplied by 5, which is equivalent to 2.5% at the surface.

Thus, breathing 0.5% carbon monoxide at a depth of 132 feet is equivalent to 2.5% carbon monoxide at the surface, which is why that