This alert will continue until 1 PM Saturday. Advertisement Young children, older adults and those with pre-existing heart and lung conditions, including asthma or heart or lung disease, are particularly at risk. Limit your outdoor activities, especially prolonged and vigorous activity. Areas affected by the alert include much of western and southern Wyoming including Yellowstone and Grand Teton National Parks, and almost all of Fremont County. For additional information on Wyoming air quality data from the Wyoming Department of Environmental Quality click here. Advertisement