Emissions testing may either be done away with (not likely as it will cause loss of federal highway dollars) or expanded . See story at this link.
For those on Ohio that don't have the tests, every two years you must pass a visual inspection and sniffer test run on rollers. If the car fails, you are required to perform required repairs (up to $250), before you get plates. This is also required when a car changes hands.
Test are currently required in the Dayton / Cincinnati, and Cleveland areas