Suppose you are sitting on a bench on Mars under open sky and under your feet there is a grate from which contantly there is an air flow.
Under the bench there is a tube through which oxygen is pumped from a generating plant and released in the air just under the bench.
This creates higher pressure and oxygen content in the air locally so that you can breath even without a special mask or suite.
I wonder whether this setup is possible on Mars.
Under current Mars conditions
In the case Mars is terraformed for greater pressure by melting its poles, but not for greater oxygen.
If the park is situated under a non-hermetic tent which, possibly, has a non-sealed opening as a door to the outside