Abstract: On December 31, 2009, Employee #1, a Senior Hard Cheese Maker, was filling a 15-gallon vessel and was exposed to Conquest, a 30% sodium hydroxide (NaOH), a cleaning-in-place (CIP) agent. Employee #1 claims a mist developed during the filling, which he inhaled resulting in mild upper respiratory chemical pneumonitis. The filling flow rate was calculated to be 3.8 gallons per minute and the three to five-minute process is performed once or twice per shift. The vessel is never allowed to go dry. On January 11, 2010, the Health and Safety Manager at Land O Lakes, Inc., notified the Division of the injury at their Tulare, CA facility. Observations of the filling process/procedures do not support evolution of a mist or a significant probability of inhalation or contact exposure. This conclusion is also supported by an evaluation of the process conducted by a certified industrial hygienist. The employer submitted documentation to support an effective health and safety program is in place. In consideration for these findings, a root cause was not determined or other factors to support exposure and alleged injury.