As altitude increases what happen to air pressure

As altitude increases air pressure decreases.

Explanation:

To understand this better we need to understand the correlation between both. It is believed that depending on the altitude the air molecules quantity will vary. So, at a lower altitude, there will be a higher presence of air molecules, while at higher altitude there will be a lower presence of air molecules. Thus, the air pressure will be higher at a lower altitude than at a higher altitude. This is also the reason why travelers show altitude problems when they travel to places with different altitudes.

Pressure decreases, and air/oxygen become thinner.