Here's a closeup showing a fairly distinct northern edge.
For such a haze pool to form, one typically needs high relative humidities, so a cool morning after a storm is best. I've always assumed that the northern edge of the haze pool lies at the southern edge of the outflow from Parley's canyon. There is some evidence supporting this view in this morning's MesoWest observations. Note in particular the 15 knot exit jet near Parley's Canyon, whereas the flow is weaker to the south in Holladay and southern Olympus Cove. In addition, the outflow from Parley's canyon is warmer (39ºF) and drier (RH=64%, not shown) compared to the airmass over Holladay and southern Olympus Cove where it is cooler 30–36ºF (RH=87–100%).
There are also times when the outflow from Parley's canyon curves southward and then eastward toward the Wasatch near the Cottonwood Canyons, forming what is known as the "Sandy Eddy." This eddy results in upslope flow in the Cottonwood Heights area. Although such flow is not evident in the surface observations above, which shows calm air or very light down-slope flow at low levels, it could be occurring aloft. Note the slight tilt of the smoke plume toward the Wasatch in the close-up photo. This might explain the thicker haze in that portion of the haze pool, although that might also be related to emissions from whatever is generating that smoke plume.