Text For Citation: 01 Item/Group: 001 Hazard: CHEMICAL

Section 5(a)(1) of the Occupational Safety and Health Act of 1970: The employer did not furnish employment and a place of employment which were free from recognized hazards that were causing or likely to cause death or serious physical harm to employees in that employees were exposed to: Employees performing dental procedures where nitrous oxide was administered to patients as an anesthetic gas, were exposed to the waste nitrous oxide at levels exceeding the recommended exposure level (REL) of 25 parts per million parts of air (PPM) as an 8 - hour time weighted average (TWA). This REL was established by the National Institute of Occupational Safety and Health (NIOSH), U.S. Department of Health and Human Services to protect employees from harmful health effects including reduced fertility, spontaneous abortion as well as neurologic, renal and liver disease: A dentist administering nitrous oxide to patients on 4/3/98 was exposed at an 8-hour time-weighted average level of 270.16 PPM. This level is approximately 11 times the REL of 25 PPM. This exposure was derived from one sample collected over a 273 minute sample period, a zero increment was added for the 207 minutes not sampled. Among other methods, reasonable and acceptable methods to correct this hazard are: 1. Utilize a properly installed and maintained scavenging system; this system should be maintained at an exhaust ventilation rate of 45 liters per minute (LPM). The flow rate should be measured by a calibrated flow device and exhaust from this system should be vented outside of the building. 2. Room ventilation should use 100outside air with sufficient separation of the supply and exhaust vents to assure good mixing and prevent "short-circuiting". 3. An additional exhaust ventilation hood placed near the patient's mouth located so as to capture exhaled gas. 4. Assure that the masks used properly fit the patient so as to minimize leakage. It may be necessary to obtain several different sizes to fit assure a low leakage fit on each patient. 5. Periodic testing for leaks in all hoses, connections and fittings. 6. Not supplying the nitrous oxide until the scavenging system is properly operating and the mask is properly fastened and placed. 7. Flushing of the system with oxygen for at least 5 minutes prior to disconnecting the gas delivery system at then end of the procedure. 8. Encourage patient to minimize talking and mouth breathing during the procedure. In the event that modifications do not limit employee exposure to levels below 25 PPM and until such time as these modifications are put in place, employees should be provided with supplied air respirators to allow them to breathe air free from excessive nitrous oxide exposure. If respiratory protection is used, compliance with 29 CFR 1910.134 is required.