The air that enters the AIIR Watch is purified using the combination of HEPA filtration and UV-C light, regardless of which unit is purchased.
To create negative pressure that air must be removed from the space, therefore it cannot be recirculated. The air that gets exhausted out is purified and safe to exhaust anywhere.
The increased Air Changes per Hour, from the action of exhausting the air out and replacing it with new supply air, does increase overall air quality inside the space through increased circulation, but the AIIR Watch is not acting as an in-room purifier in the Negative Pressure scenario. The purified air must be exhausted outside of the space to create the negative pressure needed for effective isolation.