Reducing the risk of oxygen-related fires and explosions in hospitals treating Covid-19 patients

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Abstract

On 24 April 2021, a disastrous fire in an Iraqi hospital took the lives of 82 people. Since the outbreak of the pandemic in March 2020, incidents of oxygen-related hospital fires in various countries around the world have caused over 200 deaths, the majority of whom were patients extremely ill with the novel Coronavirus. Fires involving medical oxygen are not a new phenomenon but are more common in the operating theatre where oxygen is routinely administered. In these settings, strict safety protocols are normally enforced and surgical staff are well trained in dealing with oxygen hazards. It appears that some hospitals may not have been fully prepared for the elevated risk of oxygen-related fire in intensive care units due to the high demand for oxygen therapy in severely ill Covid-19 patients. Indeed, gas producers and public health authorities were also slow to recognize and alert hospitals to the potential dangers. Oxygen is essential to life and generally makes up about 21 % of the gases in the air we breathe. Pure oxygen reacts with common materials such as oil and grease to cause fires, and even explosions, when released at high pressures. A leaking valve or hose, and openings at interfaces of masks and tubes, when in a confined space or where air circulation is low, can quickly increase the oxygen concentration to a dangerous level. Even a small increase in the oxygen level in the air to 24 % can create a fire hazard. In an oxygen-enriched environment, materials become easier to ignite and fires will burn hotter and more fiercely than in normal air. There is also a potentially heightened risk of using ethanol-based and organic solvents as cleaning agents in an oxygen rich atmospheres. This paper will provide an overview of oxygen accident scenarios that may be relevant for hospital intensive care units, with particular reference to recent events and similar accidents that have occurred in the past. The paper will recommend that hospitals recognize their chemical risks as part of their risk governance responsibility and assign chemical risk management a prominent role in their overall management. Investigation of dangerous events to extract causes and lessons learned should be utilized to highlight opportunities for prevention as well as emergency response. The industrial gas industry also needs to actively support hospitals in adoption of more rigorous risk management approaches, building on lessons learned in chemical process safety for managing flammable and explosive atmospheres.

Keywords: Covid-19, Oxygen enriched atmosphere, Hospital fire, Intensive care, Fire safety + prevention, Oxygen hazard

1. Introduction

Since the outbreak of the Covid-19 pandemic in March 2020, incidents of hospital fires in various countries around the world have caused the deaths of over 200 people, the majority of whom were patients extremely ill with the novel Coronavirus. The worst tragedy to date occurred on 24 April 2021 when a deadly fire tore through a Baghdad hospital, killing at least 82 people and injuring more than 100 others. Yet months before there was already evidence that oxygen-related fires have been occurring at alarming frequency since the start of the pandemic. JRC research conducted after a hospital fire killed 11 people in Gazantiep, Turkey on 19 December 2020, counted over 20 incidents of fires caused by oxygen-rich environments in hospitals reported in the media occurring between March and the end of December 2020 (European Commission Joint Research Centre (JRC), 2021). By June 2021, nearly 40 incidents have been reported, of which at least half resulted in death and injury. Of these, 21 resulted in at least one fatality with many incidents causing multiple fatalities, mainly among patients already extremely ill from the Covid-19 virus. Although in other cases, hospitals successfully responded to such incidents and avoided injury, most events still required evacuation of staff and severely ill patients, while at the same time depriving oxygen ventilation to those in critical condition for the duration of the event.

These incidents appear to be a direct result of the rapid increase in ventilator use in hospitals due to the COVID-19 outbreak. The concentrated presence of oxygen ventilators in an enclosed area, such as a hospital room, can create an oxygen-enriched environment. Oxygen is not toxic but it maintains combustion. It normally makes up around 21 % of the atmosphere by volume. However, when its concentration exceeds 23 %, it can create a fire hazard. Pure oxygen reacts with common materials such as oil and grease to cause fires, and even explosions, when released at high pressures.

This paper will describe how higher concentrations of oxygen can lead to serious fires in medical settings where oxygen therapy is used in patient treatment. It will give evidence of the particular dangers it poses for Covid-19 intensive care units (ICUs), where there may be several ventilators located in one room, and conditions within the ICU that can make a fire more or less likely to occur. The paper will recommend that hospitals consider ICUs as potentially hazardous environments and suggest borrowing strategies developed for chemical process safety in managing flammable and explosive atmospheres to prevent accidents that can lead to loss of life and significant material damage.

2. Oxygen hazards and hospital experiences with oxygen-related fires

In the course of saving lives and ensuring successful recovery from illness, hospitals use chemicals in many forms. Some of these chemical products may be hazardous. For example, hazardous chemicals are routinely used for cleaning, disinfecting and sterilizing work surfaces, medical supplies and instruments. Oxygen and nitrous oxide are oxidizing agents that are widely employed in healthcare for various patient treatments, such as respiratory ailments, surgery and hyperbaric therapy. The use of these oxidizers can expose staff and patients to severe fire and explosion hazards if the proper precautions are not undertaken. The hazardous character of oxygen, in particular, has become increasingly evident with the intense use of oxygen therapy for extremely ill Covid-19 patients.

2.1. Properties of oxygen

Chemists and process safety specialists recognize the hazardous aspects of oxygen in relation to its contribution to corrosion and its role in chemical reactions. The European Industrial Gases Association (EIGA) identifies the following properties of oxygen that are relevant in managing oxygen-related risks in hospitals: (European Industrial Gases Association, 2018).

Most materials burn fiercely in oxygen and the reaction can even be explosive. As the oxygen concentration in air increases, the potential fire risk increases and combustion is accelerated.

Oxygen gives no warning. As a colourless, odourless gas, and without any obvious physiological effect on humans, oxygen and oxygen-enriched atmospheres cannot be detected by normal human senses.

The heightened risk of oxygen-rich atmospheres is explained through the classic theory of the fire triangle. Three elements are required to produce a fire or explosion (see Fig. 1 ):

The fire triangle.

When one of these elements is not present, a fire cannot occur. As the oxygen concentration and pressure in the atmosphere increases, the fire will become more vigorous. At the same time, the minimum temperature or ignition energy needed to produce the combustion reaction is much lower. Moreover, as the oxygen concentration increases, the temperature of the flame will also increase higher and consequently the destructive capability of the flame is greater.

Oxygen also reacts with most materials, in particular, all organic materials and most metals, such that, almost anything can be a fuel source in the presence of oxygen. Even materials that would not normally burn in air, including fire-resistant materials, can burn vigorously in oxygen-enriched air or pure oxygen environments. Items made of elastomers, textiles and plastics with a high surface area will burn quite fiercely.

Furthermore, flammable materials, such as oil, grease and cleaning solvents, will become even more flammable in oxygen-rich atmospheres. With an excess of oxygen, they will burn with great intensity so that fire spreads quickly and burns rapidly through more fire-resistant materials, including metal components of equipment and infrastructure.

Fires involving medical oxygen are not a new phenomenon but are more common in the operating theatre where oxygen is routinely administered. In the last ten years, there has been considerable attention from the American fire prevention and anesthesiology community to prevention of fires in operating theatres after the Emergency Care Research Institute (ECRI), a global non-profit patient safety organization based in the United States, cited surgical fires in third place on its list of top ten health technology hazards. At the time ECRI estimated that 500–600 surgical fires occurred annually in the United States alone (Emergency Care Research Institute (ECRI), 2009). As a result, a number of US-based organizations including the American Society of Anesthesiologists, the Anesthesia Patient Safety Foundation, the Emergency Care Research Institute, and the U.S. Food and Drug Administration have produced written and video-based guidelines on fire prevention in operating rooms (OR) (Anaesthesia Patient Safety Foundation (ASPF), 2021; Apfelbaum et al., 2013; Emergency Care Research Institute (ECRI), 2021; U. S. Food and Drug Administration (FDA), 2018).

Notably, the 2010 campaign to raise awareness of surgical fire risks was a re-launching of awareness surrounding these risks that had been around for decades, but that had declined with the move away from flammable anesthetics in the 1960s and 1970s. The reduction in the use of flammable anesthetics, a particularly explosive fuel source in oxygen-rich environments, only removed one obvious and particularly dangerous element of the fire triangle. It was not widely recognized that other changes in surgical practice could also elevate risk. For example, the increasing use of laser technology in the 1990s introduced a potential ignition source for some types of operations, and thus, completed the fire triangle, given that oxygen treatment remains an operating room staple, and that most materials are combustible (Yardley and Donaldson, 2010).

The U.S Fire Administration, a division of the U.S. Federal Emergency Management Agency (FEMA), also issued a technical report in 1999 addressing the hazards of oxygen-enriched atmospheres while presenting lessons learned from ten flash fire incidents related to medical oxygen cylinders Incidents were mostly related to emergency medical service agencies and fire departments but not hospital settings. The findings, although clearly represent the hazards of oxygen enriched atmospheres, are limited to failures of oxygen cylinders and flow components such as regulators and valves while there is no information addressing tertiary ignition sources or electrical failures related to hospitals or ICUs.

2.2. Risk of oxygen-related fires due to intense use of oxygen therapy for Covid-19 patients

Intensive care units will generally be equipped to deliver oxygen therapy for patients who need large volumes and help keeping the air sacs in their lungs open. Covid-19 patients may proceed from low-flow oxygen supplementation via nasal cannula to a nonrebreather (NRB) face mask. If their condition worsens, they may then be offered mechanical ventilation, including non-invasive ventilation (NIV) administered via masks, high flow nasal cannula, 1 or intubation (so-called invasive ventilation). Oxygen supply can be delivered through portable oxygen tanks (of nearly pure oxygen), through pipeline delivery systems that reply on the presence of an oxygen station, including an oxygen generator and a bulk liquid oxygen supply, and various types of medical oxygen concentrators that can be portable or stationary and absorb oxygen from the air.

Oxygen-rich environments in ICUs generally can result from any number of emission sources, including leaking valves and hoses, and openings at interfaces of masks and tubes. When in a confined space or where air circulation is low, these emissions can quickly increase the oxygen concentration to a dangerous level. Almost anything can be considered fuel for an oxygen-enriched fire, and everything burns more intensely, alcohol and oil-based substances will burn most vigorously and even explosively. Apparel and linen may burn more fiercely while the efficiency of fire-redundancy of physical barriers installed to minimize virus contagion, such as cubicle curtains, may be affected resulting in an elevated burning rate. The most common source of ignition is electrical, usually a short circuit in nearby electrical equipment (and on rare occasions, the ventilator itself). However, the intense use of mechanical ventilators for Covid-19 patients may also overload the electrical infrastructure, causing electrical wires to heat up and start a fire. Notably, the intense use of oxygen for Covid-19 patients also can elevate risk in oxygen storage and supply systems for a variety of reasons, for example, by creating stress on older delivery systems, increasing portable tanks in storage, more opportunities for handling and storage errors, etc.

The most common medical oxygen sources and their characteristics are represented in Table 1 . Delivery of gaseous oxygen to ICU and medical ward endpoints can be achieved via oxygen cylinders, oxygen plants and liquid oxygen transformation systems and oxygen concentrators. While oxygen plants and transformation systems and some oxygen cylinders can be connected to a pipeline distribution system, portable cylinders and concentrators are directly connected to the equipment serving each individual patient. Thus, oxygen cylinders and concentrators can be found in close vicinity to patients while requiring substantial user interaction to operate. It is not within the scope of this study to address the hazards of liquid oxygen systems.

Table 1

3. Oxygen-related fires in hospitals

Nowadays in most parts of the world it is considered good practice for hospitals to identify and manage their safety and health risks. The risk assessment process generally starts with hazard identification, after which the hazard is evaluated in terms of frequency and potential harm and a risk level is associated with the hazard. A review of literature on oxygen-related hazards seems to indicate that oxidization hazards outside the ICU may not be routinely considered as risks of high significance.

3.1. Awareness of oxygen hazards outside the operating theatre

In contrast to surgical fires, until recently, there has been very little written about potential risks of oxygen-enriched environments outside the operating room. Sankaran et al. describes two successive incidents of electrical fires in a neonatal care unit (NICU) in 1998 (Sankaran et al., 1991). In a 1994 paper on non-anesthetic hospital, MacDonald acknowledges that, on rare occasions, incidents have occurred in association with hospital oxygen storage and distribution systems, oxygen tanks, and nebulizers (MacDonald, 1994). There is no mention of the risk of fire associated with oxygen therapy treatment in other contexts, in particular, within the ICU, including neonatal ICUs and maternity wards that also may use oxygen treatments (e.g., incubators and oxygen hoods).

Risks associated with oxygen-enrichment are most often mentioned in nursing publications but much harder to find outside this domain. In particular, very little information can be found on oxygen fire hazards in guidance on hospital management, oxygen treatment, and management of ICUs. Zuazua Rico et al. noted as recently as 2015 (or thereabouts, the publication is undated) that “The risks added to an intensive care unit under normal conditions versus to other hospital services are little analyzed in the existing bibliography. The large amount of oxygen used by mechanical ventilation devices, in addition to the number of electronic devices arranged around the patient, create an environment that is certainly dangerous that is not taken into account among workers (Zuazua Rico et al., 2021).” Zuazua also published survey results in 2015 that indicated that 73.1 % of 67 intensive care nurses at a hospital in Spain were unaware of the risks present in the hospital and in the ICU (Zuazua Rico, 2015). These observations echoed an earlier claim by Gowardman and Moriarty that “There is little reported … concerning the potential problems of mixtures of electricity and gases which support combustion in intensive care units where this combination is frequent (Gowardman and Moriarty, 1998).”

The National Health Service of the United Kingdom published its Review of Five London Hospital Fires and their Management, and exclusively targeted dissemination of lessons learned associated with the emergency response without any prevention recommendations (Wapling et al., 2009). Murphy and Foot’s 2011 paper highlights that many hospital ICUs are not adequately prepared to respond to a fire emergency, citing the frequency of hospital fires, but it does not specifically consider the possibility of fire hazards originating in the ICUs (Murphy and Foot, 2011). In its fact sheet concerning 2012–2014 hospital fire data, the U.S. Federal Emergency Management Agency (FEMA) attributed hospital fires to 12 different sources but does not mention the potential contribution of elevated levels of oxygen (U.S. Federal Emergency Management Agency (FEMA), 2021). Data presented in Hospitals Don’t Burn, the Hospital Fire and Evacuation Guide, published by the Pan-American Health Organization (PAHO) and the World Health Organization (WHO) in 2018, outlines eight main contributors to hospital fires, based on U.S. National Fire Protection Association data, but oxygen-enriched environments are not mentioned (Pan-American Health Organisation and World Health Organization, 2018). Neither publication refers to the role that oxygen treatments can contribute to fire hazards in hospitals, neither in association with ICUs or operating theatres. The data, as indicated in Fig. 2 , do show typical ignition sources for oxygen-related fires, including cooking, heating, electrical equipment and appliance malfunction, open flame, and smoking.

Causes of hospital fires in the United States 2012-2014 (NFIRS 5.0) (U.S. Federal Emergency Management Agency (FEMA), 1999).

3.2. Incidence of serious hospital fires involving oxygen prior to 2020

Although early versions of the modern oxygen ventilator have been used in ICUs since the 1970s, there is no substantial record of serious oxygen-related fires occurring outside the operating room before the mid-2000s. A search in Google in English and European languages, as well as Arabic, Chinese, Japanese and Korean, turns up one incident in which a respirator exploded in the Maimonides Medical Center in Brooklyn, New York, in 1993, killing 3 patients (The New York Times, 2021). Two fires in maternity wards, where infants are supported by oxygen incubators, are reported to have occurred in India and the United States in 2008 and 2009 (CTV News, 2021; Economic Times, 2021). Chowdhury lists 51 hospital fires that occurred between 2004 and 2012 in various parts of the world (but mostly India), of which 11 incidents are associated with incubators and ventilators. Since Chowdhury only lists the sources of the fire, it could be that several others in the list may also have been associated with intensive care units. Indeed, four more accidents indicate that babies either died or were saved from the fire, suggesting that oxygen treatment of infants may have played a role (Chowdhury, 2013).

There are other fires in hospitals reported since 2000 that also seem to indicate the possible involvement of an oxygen-rich environment. If media reports can be considered reliable, there sometimes appears to be no suspicion that an oxygen-enriched environment may have played a role even when the event started in an ICU. Those that appeared to involve oxygen-enriched environments are listed in Table 2 . For example, media reports indicate the fire in Calderon Guardia Hospital, San Jose, Costa Rica on 12 July 2005, that killed 19 people (16 patients and 3 staff), probably started from an electrical short in or near the neurosurgery unit where patients were on respirators. A medical report on the fire highlights the materials used in the hospital that probably helped to fuel it, and points out that most of the victims were trapped in the neurosurgery unit on respirators. It is notable that rapid escalation is a characteristic of oxygen-enriched fires. According to the medical report on the Calderon Guardia Hospital fire, there was “evidence of [patients] not having been able to move from their place” and it is presumed that this is because the patients were either unconscious or attached to respirators (Villalobos and Sanabria, 2006). While these explanations are plausible, another explanation is that the fire, being fed by an oxygen-rich atmosphere, spread too quickly to allow escape or rescue of these infirm individuals. The level of awareness of oxygen hazards in hospitals may also depend on the past experience of the country. As shown in Table 2 , there have been relatively recent incidents, prior to the 2020 Covid-19 pandemic, of serious fires in intensive care units in India and the United Kingdom. These incidents appeared to have caused medical communities in these countries to pay attention to the causes of the fires, in particular, the role of oxygen, rather than focusing only on the response. By and large, it appears that in many countries, it is not common practice to investigate hospital fires to identify lessons learned for preventing them.

Table 2

Non-surgical oxygen-related fires (as reported or suspected) occurring before 2020 as found in media reports, scientific articles and other publications.

A search of scientific literature produces only four articles on lessons learned for preventing oxygen-related fires in the ICU that have been published since Sankaran et al. described the incidents occurring in the neonatal intensive care unit in 1991 (Sankaran et al., 1991). Chowdhury cites 34 incidents of fires in Indian hospitals since 2004, noting that they all occurred in locations where O₂ was being administered to patients, such as the ICU, NICU, and OR and that they involved air conditioners and electrical equipment in the vicinity of the O₂ application (Chowdhury, 2013). Five years later a group of Indian authors, Dahliwal et al., also published an article on a dangerous fire that occurred in the intensive care unit of a northern Indian hospital in 2015 including lessons learned for preventing them (Dhaliwal et al., 2018). Similarly, Kelly et al. published a detailed report on a fire in an intensive care unit that occurred on 21 November 2011. In their report, Kelly et al., provide new insights on both prevention and response to fires in the ICU (Kelly et al., 2014). This incident, along with two other unrelated hospital fires in the United Kingdom, was specifically cited in Guidelines for the Provision of Intensive Care published in 2018 by the Faculty of Intensive Care Medicine (FICM) and the Intensive Care Society (ICS). The guidelines can be considered truly groundbreaking as it appears to be the first recommendations to hospital management for preventing such incidents, rather than focusing solely on how to respond should they occur (Faculty of Intensive Care Medicine (FICM) and the Intensive Care Society (ICS), 2019). In 2017 Yartsev also published a summary of the recommendations in current literature on prevention and response to fires in intensive care units (Yartsev, 2017).

Karim et al. warn about the dangers associated with medical gas management that rely mainly on oxygen cylinders, citing that emerging economies such as Vietnam, Bangladesh and India, are particularly vulnerable, but accident history also indicates that highly developed countries, such as the U.S., are not immune (Karim et al., 2016). Similarly, Sarangi et al. contend that medical clinicians are not sufficiently aware of the importance of the design, installation, commissioning, and operation of medical gas pipeline systems to hospital safety (Sarangi et al., 2018). Lack of proper installation and maintenance of the oxygen supply system can also increase the potential for an oxygen-related fire. In 2019, two people were killed and 47 injured in a fire in a nursing hospital in Gimpo, Korea because of wrong procedures during maintenance of the oxygen pipeline supply system with the location of the oxygen tank in the boiler room (where combustible materials are present) cited as a potentially contributing factor (Korea Gas News Mobile Site, 2019).

Interestingly, media reports on the recent hospital fires in Romania in 2020 and 2021 also indicate a high awareness of the potential role of oxygen. A detailed interview of the manager of the Matei Bals hospital, that experienced a devastating fire on 29 January 2021, killing 24 people (directly due to the fire or because of oxygen deprivation) shows the reporter asking very pointed questions about high oxygen usage and sources of heat and ignition (Deutsche Welle, 2021). In association with this incident, the Romania media listed 13 major hospital fires that had occurred since 2010, including one in which six infants in a maternity ward lost their lives. Despite the awareness, Romania has had two tragic Covid-19 ICU fires, perhaps attributable, in part, to ageing hospital infrastructures. The potential role of oxygen is also highlighted by the doctors held responsible by the Indian authorities for the hospital fire in Mumbai on 23 April 2021. According to their court statement, “… the fire was an accident caused by the excess presence of oxygen in the ICU (The Times of India, 2021).” According to the media, India has experienced at least 10 hospital fires in 2020 and 2021, six of which led to multiple fatalities (The Times of India, 2021).

3.3. Oxygen-related fires in hospitals treating Covid-19 patients

A search of media of reports in multiple languages, including English, Arabic, Russian, Chinese, Japanese, and Korean, as well as a number of European languages, uncovered a total of 38 oxygen-related fires or near misses occurring between May 2020 and end of May 2021 (when this article was finalized). There have been twice as many incidents reported in the media (and other publications) in the last 14 months than in the ten preceding years. As shown in Table 3 , 31 (82 %) of these incidents occurred in hospitals treating Covid-19 patients, one in neonatal care, one in cardiology, two in the emergency department, and two for which the type of patients being treated was not specified. Of the incidents associated with Covid-19 treatment, 24 incidents (77 %) started in the ICU or the Covid Ward, three (10 %) were initiated in a part of the oxygen supply network, and two occurred in storage. As indicated in Fig. 3 , an electrical fault was most commonly thought to be the source of ignition across all the incidents, including 13 (34 %) associated with short circuits without identifying the actual equipment. In seven fires the oxygen equipment itself was considered the source of ignition and in four others the air conditioners. (Chowdhury highlights air conditioners as a main starting point of most of the hospital fires occurring in India.) (Chowdhury, 2013).

Table 3

Non-surgical oxygen-related fires (as reported or suspected) occurring in 2020–21 as found in media reports, scientific articles and other publications (p. 1 of 2).