When the elevator is going upwards with acceleration a then net acceleration will be the sum of a and g(acceleration due to gravity).
Pressure = hρ ( g + a) dyne/cm2
76 × 13.6 × (g+a)/76 × 13.6 × g cm of Hg. 1 + a/g >1cm of Hg.
The final pressure should be more than 76cm of hg