Carbon Monoxide and Ghost Sightings — The Evidence Is Stronger Than You Think

There is a category of haunted house case that paranormal investigators encounter with uncomfortable regularity.

A family reports that something is wrong in their home. Multiple family members are experiencing the same phenomena — unease, visual disturbances, sounds that cannot be located, a persistent feeling of being watched. Sometimes there are headaches. Sometimes mood changes. Sometimes one family member is more affected than others, and the rest of the family cannot explain why.

Every member of that household is telling the truth about their experience. Something is genuinely happening in that home.

In a significant number of these cases, what is happening is carbon monoxide poisoning.

This is not a fringe theory. The connection between CO exposure and haunting-type experiences is documented in medical literature, has been the subject of serious academic discussion, and has direct, life-saving implications for how paranormal investigators approach residential cases.

Carbon monoxide is a colourless, odourless gas produced by the incomplete combustion of carbon-containing fuels. Any appliance that burns gas, oil, wood, or coal can produce it: stoves, water heaters, boilers, generators, and space heaters are the most common residential sources in India.

CO binds to haemoglobin in the blood approximately 200 times more readily than oxygen. When CO is present, it displaces oxygen from the blood, reducing the amount of oxygen delivered to the brain and organs.

The symptoms of low-level chronic CO exposure — the kind produced by a slow leak from a faulty appliance — are:

• Persistent headache, especially upon waking
• Dizziness and mild disorientation
• Nausea
• Fatigue and weakness
• Confusion and difficulty concentrating
• Visual disturbances — seeing things at the periphery of vision, shapes that resolve when looked at directly
• Auditory phenomena — sounds that are difficult to localise or explain
• Emotional changes — anxiety, depression, irritability, a sense of dread

The medical and paranormal research communities point to a case first documented by William Wilmer, an American physician, in the American Journal of Ophthalmology in 1921.

A family moved into a new home and began experiencing a series of disturbing phenomena. Family members reported weakness, strange sounds, feelings of being watched, visual disturbances, and the sensation that the house contained unseen presences. The phenomena were consistent across multiple family members.

Wilmer identified a faulty furnace that was filling the house with carbon monoxide. When the furnace was repaired and the CO source eliminated, all phenomena ceased immediately.

The case is over a century old. The mechanism it describes is still generating residential "haunting" reports today.

Several factors make carbon monoxide cases easy to misidentify — both by the families experiencing them and by investigators who come to help.

Symptoms fluctuate with exposure levels. CO builds up in enclosed spaces and disperses when windows and doors are opened. Families often report that the phenomena are worse at night (when the house is sealed) and better during the day (when ventilation increases). This pattern matches perfectly with variable CO exposure. It also matches what people expect from paranormal activity — more active at night, less active during the day.

Different family members are affected differently. CO exposure depends on how much time each person spends in affected areas of the home, their individual physiology, and whether they sleep in rooms closer to the source. In a family where one person sleeps in a bedroom adjacent to a faulty boiler and another sleeps at the far end of the house, the first person will have significantly more severe symptoms. This variation is often interpreted as one person being "more sensitive" to paranormal phenomena.

Pets are early warning signs. CO affects animals before humans because of their smaller body mass and faster metabolic rate. Unexplained pet behaviour — extreme anxiety, lethargy, disorientation, or death — in a household reporting paranormal activity is a serious warning sign that CO may be involved.

The gas is invisible and odourless. Unlike a gas leak that smells, or a structural problem that is visible, CO produces no sensory evidence of its own presence. A family can be experiencing significant CO exposure with no indication from the home itself that anything is wrong.

This matters specifically for the Indian residential context, because the most common CO sources in Indian homes are different from Western countries.

LPG stoves with poor ventilation. The majority of Indian kitchens, particularly in older apartments and chawls, use LPG gas stoves. In kitchens with inadequate ventilation — small windows, no exhaust fan, closed doors — incomplete combustion from a stove in regular use can produce CO at low but chronic levels. The kitchen and adjacent rooms are most affected.

Old water heaters (geysers). Gas-fired water heaters that are not regularly serviced develop combustion inefficiencies over time. In bathrooms with poor ventilation — common in older Indian residential construction — a faulty geyser is one of the most serious CO risks in the home.

Generators in enclosed spaces. During power cuts, generators are sometimes operated in enclosed garages, covered courtyards, or ground-floor spaces adjacent to residential areas. Generator exhaust contains extremely high CO concentrations. Even brief generator operation in an enclosed space can produce dangerous exposure.

Old cooking equipment. Traditional chulhas and older commercial kitchen equipment, in homes where these are still in use, are less efficiently combusted than modern equipment and produce more CO.

A carbon monoxide detector is not optional equipment for a serious paranormal investigator handling residential cases.

Before any other investigation activity begins in a residential property where symptoms are consistent with CO exposure — and the symptom list above should be checked against every residential intake report — CO levels in the home should be tested.

Consumer CO detectors, available at most hardware stores in India for ₹1,500–3,000, measure ambient CO in parts per million (ppm). Readings to know:

• 0–9 ppm: Normal. Safe.
• 10–35 ppm: Low-level chronic exposure. Prolonged exposure produces symptoms consistent with mild haunting reports.
• 35–70 ppm: Symptoms will appear in healthy adults over hours of exposure. Headache, fatigue, nausea.
• 70+ ppm: Dangerous. Immediate action required.

If a residential investigation produces a CO reading above 10 ppm from an unidentified source, the investigation stops. The family needs to open the building, contact a gas technician to identify the source, and not return to the home until the source is repaired and re-tested.

This is not a cautious overreaction. This is the job.

The paranormal investigator who walks into a home, detects elevated CO, and continues the investigation for content or case documentation without addressing the immediate health risk to the family has failed the people they came to help.

The carbon monoxide explanation, like the infrasound explanation, does something important to the standard haunted house narrative.

It does not dismiss the experiences of the people reporting them. Their experiences are real. The visual disturbances, the sounds, the feelings of presence, the dread — all of it is genuinely happening to them. CO exposure at low levels produces neurological effects that generate those experiences directly, through documented physiological mechanisms.

What the CO explanation changes is the cause — and therefore the solution.

A family living with a slow carbon monoxide leak from a faulty geyser does not need a paranormal investigator's case report. They need their geyser fixed and their home ventilated. They may also need medical assessment depending on how long the exposure has been occurring.

Getting that outcome — the family safe, the actual cause identified and addressed — is the measure of a successful residential investigation. Whether or not any unexplained phenomena remain after the CO source is eliminated is the question investigation can then address honestly.

This is what separates a serious investigator from a content creator in the residential context. The content creator comes for the haunting story. The serious investigator comes for the family.

Infrasound. Carbon monoxide. EMF. Acoustics. Structural factors. Psychological factors.

These explanations, applied systematically, account for the majority of reported residential haunting cases. In my assessment and in the documented experience of serious investigators across the Indian Paranormal Society's case history — the majority, not all.

When a residential case has been properly assessed for all of these factors, the sources have been identified and addressed where possible, and phenomena continue: that is when the investigation becomes genuinely interesting. That is the case where the documentation matters most and where intellectual honesty is most required.

But you cannot get there without doing the environmental work first. Every time.

Understanding how to assess a residential case properly — from CO testing through to full environmental baseline — is part of what my investigation courses cover. It is not glamorous. It is the work.