Borganelli G N, Primosch R E, Henry R J
Department of Pediatric Dentistry, University of Florida College of Dentistry, Gainesville 32610-0426.
J Dent Res. 1993 Sep;72(9):1275-8. doi: 10.1177/00220345930720090301.
Investigations have shown that greater than Federally-recommended levels of ambient nitrous oxide often exist in the dental workplace. The purposes of this investigation were to examine the influences of (1) operatory ventilation rate and (2) scavenger evacuation rate on ambient nitrous oxide concentrations within a closed dental operatory. This laboratory investigation utilized a scavenging nasal mask assembly (Porter/Brown) to deliver 40% nitrous oxide in oxygen, at a total flow rate of 5 L/min, to a mannequin positioned supinely in a dental chair. Eight experimental groups were assigned based on combinations of operatory air exchange rates (0, 5, 10, or 15 room air changes per hour) and scavenger evacuation rates (18.8 L/min and 21.4 L/min). Ambient nitrous oxide levels were monitored at four locations (0, 15.3, 30.7, and 61.4 cm) from the nasal mask by means of an infrared spectrophotometer (Miran 1B). The operatory air exchange rate was measured with a flow hood (Short Ridge) and manipulated to one of the desired ventilation rates. Time-weighted average (TWA) concentrations of ambient nitrous oxide (ppm) were continuously recorded at 15-second intervals with a microprocessor (DL332F Datalogger) connected directly to a microcomputer. The results demonstrated that significantly reduced (p < 0.05) ambient nitrous oxide levels were achieved with increasing room air exchange rates and the high scavenger evacuation rate. It was concluded that operatory ventilation and scavenger evacuation rates were significant control measures available for reduction of ambient nitrous oxide to Federally recommended levels.
调查表明，牙科工作场所环境中的一氧化二氮含量常常高于联邦建议水平。本调查的目的是研究（1）诊室通风率和（2）废气清除器抽气速率对封闭牙科诊室内环境一氧化二氮浓度的影响。这项实验室研究使用了一个废气清除鼻罩组件（波特/布朗），以5升/分钟的总流速向仰卧在牙科椅上的人体模型输送含40%一氧化二氮的氧气。根据诊室空气交换率（每小时0、5、10或15次房间换气）和废气清除器抽气速率（18.8升/分钟和21.4升/分钟）的组合分配了八个实验组。通过红外分光光度计（米兰1B型）在距鼻罩四个位置（0、15.3、30.7和61.4厘米）监测环境一氧化二氮水平。使用气流罩（短脊型）测量诊室空气交换率，并将其调节到所需的通风率之一。通过直接连接到微型计算机的微处理器（DL332F数据记录器）以15秒的间隔连续记录环境一氧化二氮的时间加权平均（TWA）浓度（ppm）。结果表明，随着房间空气交换率的增加和废气清除器高抽气速率的提高，环境一氧化二氮水平显著降低（p<0.05）。得出的结论是，诊室通风和废气清除器抽气速率是将环境一氧化二氮降低到联邦建议水平的重要控制措施。
