In 2021, after Philips Respironics sold millions of defective medical devices to those who struggle to breathe, the federal agency charged with protecting the health of the American public swept in.

The Food and Drug Administration accused the global powerhouse of a succession of mistakes — casting aside test results and health risks — long after the company discovered an industrial foam embedded in its breathing machines could break down and send tiny particles and fumes into the lungs of patients.

The FDA maintains that it acted as soon as it learned of the safety concerns in April 2021, just weeks before Philips launched one of the largest recalls of its kind.

But a ProPublica and Pittsburgh Post-Gazette investigation found that in the years leading to the recall, the FDA repeatedly failed one of its most critical missions: alerting the public about devices that can inflict serious harm. Over the course of a decade, the agency missed a pattern of warnings from health care workers, patients and others that something was very wrong with the company’s popular sleep apnea devices and ventilators.