The first must-take step here is to understand the scope and intensity of the risk over time. Yet the testing done in May gave only a snapshot of the problem. Long-term air monitoring would provide a much more accurate picture, and it would tell residents of surrounding communities whether the new equipment Sterigenics installed in July has actually made a difference. That information would help regulators and other public officials decide whether to take other actions. DuPage County Board Chairman Dan Cronin and state Sen. John Curran have called for revoking the company’s current state permit to operate.