Two employees of the Central Storehouse at UC Davis were taken to a hospital by ambulance Wednesday morning after they complained of lightheadedness and dizziness. Tracie Ramsey of Sutter Davis Hospital said both men, who had nitrogen dioxide poisoning, were in stable condition and were expected to be treated and released today. The UC Davis fire department responded about 8:20 a.m. to a fenced area adjacent to the storehouse, on California Avenue north of La Rue Road, but could not find any cause of the men's symptoms. Two 30-pound cylinders of nitrogen dioxide gas that the affected men had been near were tested for leaks, but none was found, according to Assistant Fire Chief Phil Davis. David Ronemus, an environmental health and safety specialist who was at the scene, said later that the men were probably affected by a leak of a small amount of gas remaining in the used cylinders. He said the test for gas leaks -- indicated by the appearance of bubbles in soapy water applied to the cylinders -- would have failed to indicate any leaks if all the remaining gas had already escaped. Nitrogen dioxide is mixed with other chemicals to form an anesthetic used at the California Regional Primate Research Center. Symptoms of acute exposure to a low concentration of nitrogen dioxide may include coughing, choking, nausea, irritation of the lungs, and pulmonary edema (the collection of fluid in the lungs). Exposure to a high concentration may cause death. The gas is neither flammable nor sensitive to impact. Matheson Gas of Newark is expected to remove the two cylinders from campus today, as previously scheduled. UC Davis police secured the immediate area where the cylinders were, but the surrounding area was not evacuated. Media on site included a reporter and photographer from the Davis Enterprise and a reporter/camera operator from KCRA -TV (Channel 3) in Sacramento. The names of the affected employees, Phillip Lacey and John Lopes, were not released to the media, but reporters were informed of their condition.