It's easy to see the Regional Asset District tax at work. Go to the zoo, a park, play, concert or museum. Like birds, ballet, kayaks or glass work? RAD has an impact there, too.

Last year, 91 organizations shared $83 million from the 1 percent Allegheny County sales tax, from the smallest grant of $2,000 for the North Suburban Symphonic Band to the largest of $17.6 million for upgrades at the Carnegie Library of Pittsburgh.

That's as it should be. Half of the money from the tax goes for property tax relief, and the other half goes to arts and cultural organizations.

But among the 108 requests for funding that the RAD board will consider Sept. 29 is one application that doesn't belong -- the one from the Sports & Exhibition Authority for $2 million to be used for operations at the David L. Lawrence Convention Center.

The convention center gets its money from events, the 7 percent hotel tax and state gambling revenue, but it always has operated with a deficit. SEA Executive Director Mary Conturo says that's true of nearly all convention centers, which often act as "loss leaders," with discounted rates below their actual costs, to lure events to a region. Then the attendees rent hotel rooms, dine in restaurants, shop in stores and take taxis to the airport, which helps the local economy.

In some years, the state has kicked in extra funds to balance the convention center budget; in each of the last two years, RAD provided $2 million.

Nearly half of the authority's financial predicament is the result of a change in the allocation from state slots revenue. The SEA is considering refinancing some debt to lessen that impact, but it says it needs another $1 million for building maintenance.

Neither factor is likely to change permanently, and we'd hate to see the RAD tax, which never was intended as a source for operating the convention center, become a regular part of its funding stream. That would hurt the small cultural groups that add to the region's vitality and have no other place to turn for funds.

The SEA needs to find a solution that doesn't rely on RAD money.