Portland had the worst air quality in the world among major cities on Wednesday morning, according to a global monitor, as wildfire smoke from dozens of fires across the Pacific Northwest blanketed the Willamette Valley.

Several days of wildfire smoke are beginning to send more Oregonians to emergency departments and urgent care clinics, according to state health officials. The Oregon Health Authority said Wednesday that visits for respiratory illnesses are running above normal in parts of the state affected by wildfire smoke.