Health care workers treating Thomas Eric Duncan in a hospital isolation unit didn’t wear protective hazardous-material suits for two days until tests confirmed the Liberian man had Ebola — a delay that potentially exposed perhaps dozens of hospital workers to the virus, according to medical records. The 3-day window of Sept. 28-30 is now being targeted by investigators for the Centers for Disease Control and Prevention as the key time during which health care workers may have been exposed to the deadly virus by Duncan, who died Oct. 8 from the disease.