by Richard Rochford
来自PBI Performance Products，Inc。E. Newsletter，由
一份有关某人内部可能遇到的住宅结构火灾的报告遇到了数据调度系统。发动机10、17和4；梯子10和4;，救援17，火5;和安全2响应。发动机10到达现场，并传输此报告：“发动机10在现场。W-3单层住宅，房屋后面有大火和烟雾。Engine10具有指挥，并通过邻居确认有人在内部。下一个发动机将铺设一条供应线。”
Fire 5 arrives on-scene and assumes command. He learns that Engine 10 found a female victim in the back of the house near the fire while performing the primary search, and is bringing her outside to the waiting rescue unit. The victim is unresponsive, is taking shallow gasping breaths, and has heavy carbonaceous soot buildup around the mouth and nose. Rescue crews receive the victim and go directly to work with advanced life support measures. The patient is transported to the nearest medical facility for further medical treatment. Unfortunately, she succumbs, and family members are notified.
Events like this happen every day. We have been given much warning about the dangers of carbon monoxide (CO) poisoning associated with fires. But, there is another danger to firefighters and victims in structural fires that is not as well recognized: That is hydrogen cyanide (HCN). Increasingly, research is pointing to hydrogen cyanide as a substance that is as much as a threat to responders and victims encountering fire smoke as carbon monoxide.
HYDROGEN CYANIDE
On February 20, 2003, a fire in The Station nightclub in West Warwick, Rhode Island, took the lives of 100 occupants when pyrotechnics were ignited during a Great White band performance. The pyrotechnics ignited substandard sound-suppressing foam, which created HCN and CO levels incompatible with life in less than 90 seconds1。
In early 2006, firefighters in Providence, Rhode Island, were tested for HCN after three separate structure fires. Eight of the 27 had elevated levels and required treatment. One firefighter collapsed on-scene and was treated for HCN poisoning.2
Most firefighters can probably recall incidents during which they experienced dizziness, weakness, and rapid heart rate (just to name a few symptoms), and did not realize that they may have been exposed to cyanide. As more firefighters become ill or die, researchers expect that HCN will be involved.
HCN is extremely toxic and seriously affects the body. Following are some facts about hydrogen cyanide3：
- HCN is 35 times more toxic than CO.
- HCN生产时产品,如羊毛、丝绸、cotton, nylon, plastic, and polymers, foam, melamine, polyacrylonitriles, and synthetic rubber burn.
- HCN可以通过吸收，吸入或摄入进入身体，并靶向心脏和大脑。
- HCN can incapacitate a victim within a short time.
- HCN的血液中有一个半衰期为一小时。
- HCN is highly flammable, and most of it will burn away during combustion.
氰化氢从何而来？
氰化氢是日常生活中使用的材料燃烧的副产品（绝缘，地毯，衣服和合成材料）。罪魁祸首是氮。在适当的情况下，大气中的氮气可以促进燃烧过程中少量氰化物的形成。高温和低氧浓度有利于形成氰化物气体。草剪，绿色木材，烟草，棉花，纸，羊毛，丝绸，杂草和动物尸体的燃烧可能含有一些氰化物氰化物。但是，真正的罪犯是人造塑料和含有氮的树脂的燃烧，尤其是在火很热且在封闭空间中的情况下。在燃烧过程中产生氰化物气体的普通人为材料包括尼龙，聚氨酯，三聚氰胺和丙烯腈。这些材料无处不在，在建筑家具，车辆，泡沫绝缘，地毯，窗帘，电器，许多塑料和服装材料中无处不在。
Despite burning away during combustion, objects within a fire continue to produce cyanide as long as their temperature remains elevated. Given that HCN is 35 times more toxic than CO, firefighters should give serious consideration to this deadly gas. Scientists are just figuring out what long-term effects repeated exposures will cause. Until research is definitive, firefighters must protect themselves against the effects of HCN. Many would suggest that the answer lies with SCBA. For years, wearing an SCBA was optional. Today, it is mandatory. The question is: When dp firefighters remove their SCBAs? HCN may still be present in the atmosphere in high concentrations during overhaul. Firefighters must wear their SCBAs until HCN levels have been assessed with atmospheric air monitoring.
How Much Hydrogen Cyanide Gas Can Kill?
这职业安全与健康管理局（OSHA）lists the threshold odor concentration for detection of HCN as 0.58 parts per million (ppm) by the most sensitive individuals,4但是，消防员和其他因燃烧材料而暴露于烟雾的人可能无法闻到气体的气味。同样，多达40％的人群缺乏闻到HCN的遗传能力。氰化氢通过代谢窒息导致快速死亡。空气中的致命浓度（LC50浓度估计杀死50％的测试人群）取决于暴露期限。下表详细介绍了人类估计的空气中的LC505。
| LC50 PPM | 暴露时间 |
| 3,404 PPM | 1分钟 |
| 270 PPM | 6to 8 minutes |
| 181 PPM | 10 minutes |
| 135PPM | 30 minutes |
这American Conference of Governmental Hygienists reported that workers exposed to hydrogen cyanide concentrations ranging from 4 to 12 ppm for seven years reported increased headaches, weakness, changes in taste and smell, throat irritation, precordial pain, and nervous instability. Workers exposed to low concentrations developed enlarged thyroid glands. The following permissible limits have been established:
- OSHA允许的HCN暴露量为8小时的平均水平为10 ppm（TWA）。
- 这National Institute for Occupational Safety and Health (NIOSH) lists a short-term exposure lower limit of 4.7 ppm for workers. The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned 4.7 ppm as a worker ceiling limit.
- 这word “SKIN” in the NIOSH and OSHA listings means that hydrogen cyanide is absorbed through the skin and eyes.
SYMPTOMS OF EXPOSURE
消防员和吸入与烟雾相关的氰化氢的受害者通常会遭受认知功能障碍和嗜睡，这会损害逃脱或进行救援行动的能力。6Exposure to low concentrations (or initial exposure to higher concentrations) may result in stupor, confusion, flushing, anxiety, perspiration, headache, drowsiness, tachypnea. Exposures to higher concentrations of HCN result in prostration, tremors, cardiac arrhythmia (which can be delayed two to three weeks after the fire exposure), coma, respiratory depression, respiratory arrest, and cardiovascular collapse.
PREHOSPITAL MANAGEMENT
这prehospital treatment of acute cyanide poisoning entails removing the patient from the source of cyanide, implementing supportive modalities including 100 percent oxygen and providing cardiopulmonary resuscitation, if necessary. There is some concern about providing antidotal treatment to victims exposed to HCN from smoke inhalation.
Antidotal treatment of smoke-inhalation victims on the basis of presumptive diagnosis of HCN poisoning in the prehospital setting is discouraged because nitrate-based kits is the only form of antidote available in the United States. These kits can pose dangers for smoke inhalation victims with concomitant carbon monoxide poisoning. Carbon monoxide displaces oxygen from hemoglobin to form carboxyhemoglobin, whereas nitrates in cyanide antidote kits displace oxygen from hemoglobin to form methemoglobin. The cumulative oxygen-depriving effects of nitrates and carbon monoxide can be fatal.
A new antidote called “hydroxocobalamin” has been effectively used in France for the past 10 years. It is designed specifically for use on-scene or at the hospital for acute HCN poisoning from any source. Hydroxocobalamin neutralizes cyanide by fixing it to form cyanocobalamin (vitamin B12), which is excreted in the urine. It does not reduce the blood’s capacity to carry oxygen.
氰化物暴露是封闭空间火灾中烟雾吸入的预期结果。研究表明，氰化物中毒可能是丧失能力和死亡的重要原因，也是消防员慢性健康并发症的潜在来源。这也表明氰化物可以独立于或可能与一氧化碳协同作用，从而引起发病率和死亡率。由于火灾引起的烟雾中的氰化物气体可能会迅速致命，因此在院前环境中与烟雾吸入相关的氰化物中毒的早期治疗对于挽救生命至关重要。此外，国际消防战士协会本地799（罗德岛当地799，2006）建议遵循以下培训格式7：
- Training and equipment. Develop and institute a training program that focuses on making members aware of the hazards of hydrogen cyanide at fires. Include the following:
a.) the reason cyanide is more significant today than ever before.
b.) The chemistry, identification, and toxicology of cyanide.
c。）与火灾，EMS和医院的氰化物有关的医疗问题。
d。）消防员不能仅仅依靠他们过去的经验来确定特定气氛是否安全的原因。 - Compliance. Develop enhanced compliance with mandatory mask regulations. Company officers must focus on protecting their members while ensuring that SCBAs are used. I tell my members: “Your SCBA bottle contains 4,500 psi. From 500 to -4,500 psi belongs to your department for the work that you perform; from 0 to 500 psi belongs to your family.”
- SCBA培训艰难的操作训练，例如攀登梯子，在屋顶上工作以及播出时进行沟通。
- 火后去污。每次火灾后，洗净/冲洗掉您的交场装备。返回车站后，请确保淋浴并更换制服。
- Medical community. It needs to be made aware of the presence of cyanide in modern-day smoke and should keep the possibility of cyanide poisoning in mind when presented with a smoke inhalation victim.
- Public education (general public, media, and legislators). Alert the public to the dangers of smoldering and burning plastic and other cyanide-containing fuels. They should also understand that the dangers associated with cyanide may be present before flame is present and that it can incapacitate during the incipient stage of fire and prevent escape.
Do not let the benefit of having this information stop here. Share it with emergency responders and the public. Be sure to wear your personal protective equipment and use caution and common sense.
References
1. Providence Journal。
2. Milkovits，Amanda，“罗德岛消防员的氰化物中毒的细节”，2006年4月。
3。Riley, Carlin, Steven Young, “Firefighting in Canada,” Canadian Firefighter & EMS，2007-2008。
4。Occupational Safety and Health Administration,www.osha.gov。
5。。Hathaway, et al 1991. Proctor and Hughs’ Chemical Hazards of the Workplace，。第三版（纽约，纽约：范·诺斯特兰·雷恩德（Van Nostrand Reinold），1991年）。
6。Health Hazard Manual for Firefighters。（新泽西：布朗，1990年，21-22。
7。International Association of Firefighters Local 799, “Recommendations to be learned to prevent exposures to cyanide,” 2006.
Additional Resources
Eckstein, Marc, MD, & Paul Maniscalco, M MPA, – “Focus on Smoke Inhalation–The Most Common Causes of Acute Cyanide Poisoning,” April 2006.
First Responder, “Fires: What’s in that smoke?” 2003.
队长阿里克Rochford是场事故安全fficer with Jacksonville (FL) Fire/Rescue,) assigned to the Second Battalion. He educates firefighters throughout Florida on the effects of toxic products of combustion and conducts atmospheric air-monitoring research at structure fires. He is a hazardous materials technician and a WMD/advanced bio/chemical sampling instructor.
Subjects:氢氰化物中毒,fire-based EMS
