What layer of the atmosphere has the highest pressure?

TroposphereWhat layer of the atmosphere has the highest pressure?
on a technical note there is atmoshear all through out the earth dirt has gasses like oxyen in it and it actually has a larger percentage of oygen than breathable air does as does water but you cannot breath very dense oxygen and hydrogen as you would drowned in them so the core has the densest but not the most useable atmosphear.What layer of the atmosphere has the highest pressure?
All aviation instruments are calibrated on the Standard Atmosphere (SA) which is defined as such:


1013.25 hPa (29.9 Mg Inch) at sea level.


from there, the pressure goes down with one hPa (a.k.a millibar) per 8 meters of altitude. But this changes with altitude and at about 500 hPa, which is about 5 km of altitude or half way to the tropopause; the top of the troposphere, the pressure goes down one hPa per 16 meters.
lowest layer highest pressure
The one we live in, called the ';troposphere.';
The Biosphere
The troposphere, the lowest layer.