COLUMBIA, Mo. (AP) - A Planned Parenthood clinic in Columbia will reopen after closing for a few hours when employees reported an unknown hazardous materials emergency. Assistant Fire Chief Brad Fraizer says four clinic employees had eye and throat irritation and were coughing when firefighters responded to the clinic Wednesday afternoon. None of the employees required medical treatment. The Columbia Daily Tribune reports the fire department's hazmat team conducted an air quality test and found an irritant in the air. Investigators are trying to identify the substance. Fraizer says the irritant was confined to one room. No property was damaged. Columbia police are investigating the incident. The building was ventilated and Planned Parenthood Great Plains said the clinic would be open Thursday.