Supreme Court to hear cross-state air pollution rule

With the cross-state air pollution case before the Supreme Court on Tuesday, USA Today takes a look at Maryland's measures against air pollution.

It's called the "radar wind profiler" and by measuring wind speed and direction it helps find out who is polluting Maryland's air, USA Today reports.

The Environmental Protection Agency's rule would require that as many as 28 upwind states cut ozone and fine particle emissions for their Mid-Atlantic and Northeast neighbors.

But 24 states have called on the justices to uphold a federal appeals court ruling, which struck down the EPA rule.