Carbon Monoxide Expert Witness

Carbon monoxide is colorless, odorless, and produced whenever fuel burns incompletely. It's one of the most common causes of poisoning in the United States, and one of the most commonly missed. Early symptoms like headache, nausea, dizziness, fatigue, and confusion look like the flu. Whole families get sick at once and assume it's a virus. Emergency departments send patients home without testing. By the time someone connects the symptoms to a furnace, generator, or water heater, the evidence may be gone and the injury may be permanent.

Carbon monoxide cases require experts on two fronts. Engineers and investigators establish where the gas came from and why it reached living space. Medical experts establish how much exposure occurred and what it did to the person, often months after the fact.

Where the CO came from

Every CO case begins with a combustion source and a failure that let exhaust escape. Common sources include:

• Furnaces and boilers. Cracked heat exchangers, blocked or disconnected flues, improper venting, and lack of combustion air
• Water heaters. Backdrafting from poor venting, especially after nearby changes like a new exhaust fan or tighter windows
• Portable generators. Run in garages, basements, or close to windows and doors, often during power outages
• Vehicles. Cars left running in attached garages, a growing problem with keyless ignition vehicles that are easy to forget
• Gas ranges and ovens. Used for heating or with blocked burners
• Fireplaces and wood stoves. Blocked chimneys and closed dampers
• Pool and spa heaters. A recurring source in hotels, where exhaust can enter guest rooms above or beside equipment rooms
• Boats. Exhaust accumulating near swim platforms or inside cabins

Liability usually follows the failure. HVAC contractors who installed or serviced equipment improperly, landlords who ignored complaints or failed to maintain systems, hotels that didn't install detectors or inspect equipment, manufacturers whose products were defective or poorly warned, and home inspectors who missed obvious venting problems all appear as defendants.

Detectors and codes

CO alarms are cheap and effective, so their absence or failure is often central. The model building codes widely adopted in the U.S. require CO alarms in dwellings with fuel-burning appliances or attached garages, and many states extend requirements to rentals and hotels. Residential alarms are listed to UL 2034, which sets when alarms must sound based on concentration and duration. Installation requirements now appear in NFPA 72. Questions in these cases include whether an alarm was required, whether one was installed, whether it was in the right location, whether it was expired, and whether it worked.

Reconstructing the exposure

Measuring the exposure is harder than it sounds. Carbon monoxide binds to hemoglobin far more strongly than oxygen. The standard test measures carboxyhemoglobin (COHb) in the blood. But COHb drops steadily once the person reaches fresh air, and much faster on supplemental oxygen.

A level drawn hours after rescue, after EMS gave oxygen, can dramatically understate the actual exposure. Defense experts sometimes point to a low hospital COHb as proof of a minor exposure. A qualified expert can back-calculate from the timeline and treatment to estimate what the level likely was. Smoking also raises baseline COHb and needs to be accounted for.

Standard pulse oximeters can't tell oxygen from carbon monoxide on hemoglobin, so a normal pulse ox reading means little. Other evidence helps reconstruct exposure:

• Fire department and utility readings taken at the scene
• Alarm data, since some detectors log peak concentrations
• The number of occupants and pets affected and the timing of their symptoms
• Symptom improvement when away from the building
• Testing and combustion analysis of the appliance
• Computer modeling of CO concentrations based on the source, building volume, and air exchange

The injury

CO injury ranges from short-lived symptoms to death. The cases with the highest damages usually involve brain injury.

Acute effects include headache, nausea, confusion, loss of consciousness, seizures, cardiac injury, and death.

Delayed neurological sequelae can appear days to weeks after an apparent recovery. They include memory problems, cognitive decline, personality changes, mood disorders, and movement abnormalities. A significant minority of patients with serious exposures develop these effects. They're often missed because the person seemed to recover.

Long-term cognitive injury may be documented through neuropsychological testing and brain imaging. Damage to deep brain structures like the globus pallidus is a classic finding, though imaging is often normal even when testing shows deficits.

Hyperbaric oxygen therapy is often used for serious exposures. Clinical trial evidence suggests it can reduce later cognitive problems in some patients, though its use remains debated. Whether a patient should have been referred for hyperbaric treatment is sometimes a medical malpractice question in its own right, as is an emergency department's failure to test for CO in a patient with suggestive symptoms.

Experts these cases draw

• Mechanical or HVAC engineer for appliance function, venting, installation, and maintenance
• Fire and gas appliance investigator for source identification and scene examination
• Industrial hygienist or exposure modeler for concentration estimates and exposure reconstruction
• Hyperbaric or emergency medicine physician for acute treatment, COHb interpretation, and back-calculation
• Neurologist for neurological injury and imaging
• Neuropsychologist for cognitive testing and documenting long-term deficits
• Toxicologist for general causation and dose-response
• Product liability engineer or human factors expert when a generator, appliance, or detector design or warning is at issue

See also when your case needs two expert witnesses.

Preserve the source

Appliances are often repaired, replaced, or discarded within days, sometimes by the same contractor whose work is in question. Send preservation letters immediately. Arrange a joint inspection before anything is altered, and collect utility, fire department, and service records.

Common questions

Is a normal COHb level at the hospital proof of minor exposure?

No. Levels fall quickly with time and oxygen therapy. The timeline and treatment have to be considered.

Can CO cause permanent brain injury?

Yes. Serious exposures can cause lasting cognitive and neurological problems, sometimes appearing after a delay.

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