How Does Carbon Monoxide Poisoning happen in a hotel?

At some point you have probably seen a headline about a hotel stay gone terribly wrong due to carbon monoxide poisoning, never thinking that you or a loved might fall victim to this seemingly rare event. You check in to a hotel, you never even consider that you might be putting your lives at risk. If you thought about it, you would likely think there must be guidelines and regulations every hotel must comply with to continue to welcome guests to their establishments. This is an assumption the public makes daily.

Where is the shortfall in making sure hotels are safe from carbon monoxide?

First, just because the hotel name includes a chain, such as Days Inn, Embassy Suites, Best Western, doesn’t mean that critical decisions about safety are being monitored by a national organization that has the technical expertise that is required to prevent carbon monoxide poisoning. We believe that all hotel franchisors (such as Hilton, Holiday Inn, Hyatt) should be doing the education, inspecting and training to prevent these incidents, In practice, too many chains fail to take critical safety measures to eliminate hotel carbon monoxide poisonings.

No one should ever be CO poisoned in a hotel. Hotels are supposed to have knowledgeable engineers on staff and contract out maintenance of HVAC systems. As importantly, hotel franchisor fully understand the risk of CO poisoning and should be demanding carbon monoxide alarms in every space where people sleep. Yet in virtually every situation where there is a serious hotel poisoning, no carbon monoxide alarm warned of the danger.

venting causes hotel carbon monoxide poisoning

Hotel carbon monoxide poisoning often starts with improper venting in a hotel equipment room. In this former chain hotel in Green Bay, Wisconsin, a severe carbon monoxide incident occurred because a conventional boiler was replaced with a higher efficiency boiler but the exhaust venting was cobbled into the hotels masonry chimney instead of being exhausted with new pipes, directly out the sidewall of the hotel. 

How do hotel carbon monoxide poisonings occur?

In order for a carbon monoxide poisoning to occur, there has to be incomplete combustion of the natural gas fuel which is used in the hotel in appliances that are used to generate heat, whether that be to heat rooms or water. In order for there to be carbon monoxide to build up inside the breathable air (ambient air) in a hotel, incomplete combustion must have occurred in one of the fuel burning appliances. In complete combustion, natural gas and oxygen combust to create two by products, H2O and CO2. With incomplete combustion the byproducts will also include carbon monoxide, CO, and unburned hydrocarbons.

Not enough Oxygen. The first thing to understand about avoiding carbon monoxide in hotels is that if there isn’t enough oxygen to burn all of the natural gas supplied to the flame, you will get CO. Insufficient oxygen can happen because there isn’t enough air available to the flame (called “combustion air”) or there is too much fuel supplied by the regulator which controls how much gas pressure is getting to the flame. Each HVAC system when designed required a certain amount of combustion air be available for the flame. In most commercial establishments, that combustion air must be ducted into the space where the fuel burning appliance is burning. If that venting is undersized, obstructed or modified improperly, CO will be created. It is critically important that manufacturers recommendations for combustion air be strictly complied with in installations and be inspected often for breaks or obstructions.

Too much fuel. Each fuel burning appliance that burns natural gas has a device inside of it that controls the amount of gas which flows to the flame. These devices can break or be set improperly. If there is not enough gas for the flame, the flame will be said to run lean. If there is too much gas for the flame, it is said to run rich. Rich running appliances can create extraordinary amounts of CO and are going to be dangerous.

Quenching of Flame at Burners. Incomplete combustion can also occur because there is a problem with the burners themselves. For complete combustion, the burners must be clean, otherwise the flame is quenched, meaning it doesn’t burn uniformly, and pockets of partially burned fuel occur. Partially burned fuel equals carbon monoxide. Cracked heat exchangers can also create CO at the burners because they interrupt the designed air flow of oxygen and gas at the burners.

Problems with Exhaust System, Flue Gases. In homes, we think of furnaces and fireplaces as having chimneys to exhaust out the smoke and other by products of combustion outside. In a modern fuel burning appliance, there should be no smoke and we usually talk in terms of exhaust venting or vents. No furnace or commercial hot water heater can vent the by products of combustion, even if just CO2 and water vapor, inside a building. The corrosion that would occur from the water vapor alone would be a serious problem. But in a hotel boiler or furnace, these units are designed to move the air through the units in such a way that if the exhaust isn’t completely vented outside, it will create back pressure to the flame. Back pressure to the flame, also called negative pressure, will cause incomplete combustion, which creates CO.

The creation of CO in the exhaust alone, isn’t a life-threatening problem initially, as long as all of that exhaust is vented outside. However, if CO is being created in the exhaust, it will also come with excess water vapor and other under burned hydrocarbons, which will over time create severe corrosion inside the exhaust piping. A breach in an exhaust pipe that has high concentrations of CO, will cause a rapid increase in carbon monoxide in ambient air of the hotel.

Making venting problems even more serious is that when there is a breach caused by this corrosion, it reduces exhaust pressure, further increasing the amount of carbon monoxide in the escaping exhaust.

What Appliances Cause Hotel Carbon Monoxide Poisoning?

Hotel poisoning primarily comes from three different places:

  • The system used to heat the water that is used by guests in bathrooms, for things like showers and used by the hotel staff for laundry, this is referred to as domestic hot water;
  • The HVAC system to heat the room or common areas of the hotel;
  • Pool heaters, used to heat the hotel pool.

In this blog, we will focus on the problems with domestic hot water. We will in later blogs treat HVAC system problems and pool heaters.

Hot Water Heater Malfunctions Cause Hotel Carbon Monoxide Events

One of the main causes of lethal levels of carbon monoxide in a hotel setting are water heaters for the hot water consumption of the hotel, the domestic hot water. Domestic hot water heaters and boilers are all susceptible to  equipment neglect, improper installation and improper venting. Basic recommendations for hot water heaters are universal–from quarterly flushing to ultimately replacing units ten years or older. In all cases a professional is a must when running a check-up. All hotels should be following the appropriate standards required to guarantee the safety of guests in a commercial environment.

One use of domestic hot water is hot showers for multiple rooms. The majority of hotels use a boiler versus a residential type hot water heater, powered by gas, sending hot water through pipes to where it is needed. These systems will also have a storage tank to keep up with peak periods of demand for hot water. The tank storage system is also one of the leading causes of in-room exposure and fatality. Wherever there is combustion we have the possibility for improper combustion and ultimately the threat of lethal carbon monoxide levels.

All members of the public have the expectation that establishments such as a hotel will have had proper and appropriate installation of all fuel burning appliances. Experts agree that hot water systems are not designed to last forever and anything over a decade old is suspect for malfunction. So, we expect that any hotel chain (the franchisor) would demand that each hotel regularly have their units checked, properly maintained and have proper reserves and budgets for replacement when scheduled, not only upon failure. A run to failure program for a fuel burning appliance is a run until someone gets poisoned plan. 

Regular maintenance and inspection would include simple tests to determine the efficiency of the combustion at the source. Inspection involves checking carbon monoxide levels at every juncture and determining whether venting is secure and adequate. Since most hot water systems are located centrally in the hotel building to provide easiest access to all rooms, proper venting is absolutely vital. Guidelines exist to insure what are and what are not acceptable levels of carbon monoxide. All manufacturers have manuals, maintained online for proper installation and maintenance of boilers. See for example

We know that carbon monoxide is odorless and cannot be detected without carbon monoxide detectors. And those detectors should be checked bi-annually to determine if they are fully functioning. Carbon monoxide alarms do not last forever and lose some of their sensitivity each year. Manufacturers’ recommendations must be followed. We will do a separate blog on this later.

However, hotel boiler systems in general are required to be inspected by licensed state inspectors. An inspection is required upon initial installation and then periodically depending on type of boiler and other factors. It is often up to the hotel to make sure their hot water system has a current inspection, to keep records of maintenance and repairs and to document any malfunctions in the system. It is also the hotel’s responsibility to maintain these records along with prior inspection documents readily accessible in one place in case of inspection. These regulations apply to all types of hot water systems which use combustion to operate. However, this appears to be a weak point in hotel management in some cases and inadequate or incomplete records are the result.

We assume that the dangers of carbon monoxide poisoning in a hotel environment affect only guest rooms. However, the same danger exists in other areas of the hotel. A hotel laundry room, for example. If you experience symptoms in or out of the guest room area, they are just as urgent.

I cannot stress the urgency enough. Carbon monoxide poisoning can lead to permanent neurological deficits and fatality. Children and compromised individuals are most at risk for severe consequences, but it is serious for anyone exposed. Symptoms start as headaches, dizziness, stomach upset, weakness, confusion and can proceed to vomiting, chest pain and ultimately unconsciousness or death. It is urgently necessary to respond immediately to the onset of these symptoms and not discount the possibility of carbon monoxide poisoning assuming that a hotel has taken all precautions to protect its guests.

At this point, you might ask why this problem exists when a simple carbon monoxide detector in each room and area in the hotel could prevent such occurrences? The American Hotel & Lodging Association argued that it was cost prohibitive for them to install detectors in every room and the requirement was eliminated even though some states have decided that it is an essential precaution. This decision maintained that carbon monoxide was an acceptable risk due to economic factors.

This position is absurd. Bought in bulk, combination CO and Smoke alarms are not appreciably more expensive than the smoke detectors which are in every room.

Imagine checking into a hotel late at night and promptly going to sleep to prepare for your ongoing travel plans in the morning. The hotel is staffed by one person behind the desk. If your hotel has a carbon monoxide detector, it is probably in the concrete block mechanical equipment room. Sometime during the night the alarm goes off, but no one hears it. It is not in the area where guests are most at risk, in their rooms where they are sleeping. Or you decide to take a quick shower before turning in but there is no hot water. The desk person graciously finds the maintenance person who quickly lights the pilot light as he has done several times lately. No thought is given to the fact that the equipment has been malfunctioning regularly and that pilot light failure might have more serious causes.

We will have a separate blog specific to carbon monoxide detectors.

Why are inspections then doubly vital to hotel operations and what should those inspections entail? One might assume that inspections are more technical in nature. However, many hotels use in house “engineers” to address maintenance issues rather than someone specifically trained in the maintenance of their particular systems. And often the issues are so glaringly obvious it is incredible they are overlooked by even a layman. Venting systems mistakenly capped off. Venting systems not installed to manufacturers’ specifications. Many of the problems reflect the desire to save money over all other considerations.

There are many ways a hotel franchise owner might fail to put into place proper protocols for the safe operation of his facility. From inadequate staffing, to improper maintenance, to sheer neglect, these failures come together to create a potentially deadly environment for the public. All of which might have been avoided by utilizing a trained professional familiar with their particular system and aware of the importance of keeping safety first in the hospitality industry.

As the public we have certain expectations about those industries who welcome us into their doors. We expect that they have conformed to the laws, abide by all guidelines, and assume a responsibility no less serious than we would expect of an airline, public transport or any other entity utilized regularly by the public. The hotel environment is just as responsible for safety because we are often there in our most vulnerable state; asleep.

Now, remember, I said earlier that paperwork consisting of maintenance schedules, known malfunctions and previous inspections are required to be kept on site, readily available for inspection. There should be concise records related to carbon monoxide detector alarms in all areas, documented coverage of any type of pilot light outages, and sign offs by qualified maintenance personnel. There should also be documentation of any guest complaints of symptoms that might be related to a suspected malfunction.

Your hotel staff has a duty to take any and all complaints or concerns seriously when dealing with the potential for carbon monoxide poisoning. As well as a responsibility to assist in any way possible with any medical intervention which might be needed. We have a certain expectation for fire safety and the same expectation exists for protecting us from this invisible killer.

In our next blog, we will discuss the mortal risk of carbon monoxide poisoning from hotel pool heaters.

Becca Martin contributed to this blog.
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