Guidance Addresses Nitrous Oxide Exposure among Maternity Ward Workers
New guidance published by Britain’s Health and Safety Executive (HSE) is intended to help protect workers on maternity wards from exposure to nitrous oxide, a colorless anesthetic gas used in healthcare. Nitrous oxide is commonly mixed with oxygen to help control pain during childbirth, presenting an exposure risk to workers who spend extensive time in labor rooms. Workers’ risk of exposure to higher levels of nitrous oxide depends on how well exhaled gas from women in labor is controlled, according to HSE. Symptoms of exposure to nitrous oxide include difficulty breathing, drowsiness, and headache, notes the NIOSH Pocket Guide to Chemical Hazards, while HSE stresses that exposure to high levels of the gas over time can cause health effects like neurological problems and anemia. HSE’s long-term workplace exposure limit for nitrous oxide is 100 ppm or 183 mg/m3 as an eight-hour time-weighted average. For comparison, the NIOSH recommended exposure limit for exposure to waste anesthetic gas is 25 ppm or 46 mg/m3 as a time-weighted average over the time exposed. There is no OSHA permissible exposure limit for nitrous oxide.
HSE’s guidance describes three types of control measures used to address the risk of occupational exposure to nitrous oxide, in order from most to least effective: a demand valve and mouthpiece or facemask used to capture patients’ exhaled breath, an extraction or scavenging system with an extraction unit located close to patients’ breathing zones, and general ventilation. HSE explains that a demand valve and mouthpiece or facemask system is most effective “because the exhaled air is not released back into the room, as long as the mouthpiece or facemask is not removed before the patient exhales.” General ventilation alone “is unlikely to achieve adequate control” due to its distance from the source and because it relies on the effectiveness of room ventilation, the guidance states.
Other topics covered in the guidance include exposure monitoring and the role of effective management systems in controlling the risk of exposure to nitrous oxide.
The new guidance was developed by HSE, Britain’s national regulator for workplace health and safety, in collaboration with maternity specialists in the National Health Service, the U.K.’s publicly funded healthcare systems. It can be found on the HSE website. According to HSE, the guidance is also relevant to health and safety professionals working in other parts of the healthcare sector in which nitrous oxide is used.
Related: AIHA’s white paper “Recognition, Evaluation and Control of Waste Anesthetic Gases in the Post-Anesthesia Care Unit” discusses the hazards of anesthetic gases used to keep patients unconscious during surgery. These gases, such as nitrous oxide and the halogenated agents isoflurane, desflurane, and sevoflurane, can leak into the surrounding room and are present in the exhaled breath of patients.
