PHILADELPHIA (AP) — Philadelphia officials say the refinery explosion and fire from last week has not formally been placed under control, but nothing of concern to public health has been found.

Fire Commissioner Adam Thiel says investigators haven't been able to go to some areas at the Philadelphia Energy Solutions Refining Complex because they haven't yet been assessed by a structural engineer. He said understanding the cause and origin of the early Friday blast will take "quite some time."

Dr. Caroline Johnson, city deputy health commissioner, said Tuesday "very aggressive" air monitoring has turned up nothing of concern, and emergency rooms haven't reported increases in people with respiratory distress. She says air samples tested for 61 chemical compounds found "very minor" elevations of acetone and ethanol Friday but nothing since then.

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