How carbon monoxide harm happens

Carbon monoxide poisoning is the harm caused when a person breathes in carbon monoxide, a colourless, odourless gas produced by the incomplete burning of fuels, which starves the body's organs of oxygen.

Carbon monoxide has no colour, taste, or smell, so it poisons people without warning. Carbon monoxide is a poisonous gas produced by the incomplete burning of fuels such as gas, oil, coal, turf, and wood. When it is inhaled, it binds to the part of the blood that carries oxygen and forms carboxyhaemoglobin, which starves the body's organs and tissues of oxygen (Health Protection Surveillance Centre). It can build up when a fuel-burning appliance is faulty, when a flue or chimney is blocked or disconnected, or when a room is poorly ventilated.

The most common sources in Irish homes are boilers, gas and oil heaters, cookers, open fires, and solid-fuel stoves. Because the early symptoms of exposure resemble flu, food poisoning, or ordinary tiredness, people often do not realise the cause, and pets in the home are sometimes affected first. Gas Networks Ireland advises annual servicing of appliances by a registered installer, adequate ventilation, and correctly sited alarms as the main protections.

Who may be liable

You claim against whoever was responsible for the danger, and sometimes more than one party is. Carbon monoxide claims in Ireland usually follow one of four routes, depending on how the exposure happened. Establishing which party was responsible, and on what legal duty, is the heart of the claim. The table below sets out the routes and the typical defendant for each.

This page deals specifically with carbon monoxide poisoning caused by faulty or poorly maintained fuel-burning appliances, flues, and ventilation. For injuries in rented homes that do not involve carbon monoxide, the general claims against landlords and property managers guide is the better starting point, and for other accidents in short-stay accommodation see hotel accident claims.

The gas installer route reflects a strict Irish rule: only a Registered Gas Installer may lawfully carry out the installation, servicing, or repair of gas appliances and pipework, a requirement given legal effect in 2009 and overseen by the Commission for Regulation of Utilities (Register of Gas Installers of Ireland). Where a poisoning follows a poorly fitted flue, a missing cap, or an inadequate service, liability can rest with the installer or servicer, who is required to hold public liability insurance.

A fifth situation arises at work. Where carbon monoxide exposure happens in the course of employment, for example in a commercial kitchen, a plant room, an enclosed garage, or around biomass fuel storage, the employer's duty under the Safety, Health and Welfare at Work Act 2005 may apply instead. The Health and Safety Authority reports that carbon monoxide has caused several work-related deaths in Ireland, and higher-risk occupations include garage mechanics, welders, and car-park and dock workers.

Alongside the general duty, specific Irish regulations bear on workplace carbon monoxide: the Chemical Agents Regulations 2001 (S.I. No. 619 of 2001) require the employer to assess and control exposure, and the Confined Spaces Regulations 2001 (S.I. No. 218 of 2001) apply where the gas may build up in an enclosed space such as a wood-pellet store. The Health and Safety Authority issued a safety alert after a fatal wood-pellet storage incident, warning that pellets can release carbon monoxide in confined storage and that no one should enter such a space without confined-space training. Carbon monoxide is also classed as a reproductive toxin, so exposure carries particular risks in pregnancy. Workplace exposure is dealt with in the occupational illness guide.

Landlord obligations in rented homes

A landlord must fit carbon monoxide alarms where necessary and keep fuel-burning appliances safe. In the private rented sector, the governing instrument is the Housing (Standards for Rented Houses) Regulations 2019, which came into operation on 1 May 2019. Regulation 6(6) is the specific carbon monoxide provision:

"Each house shall contain, where necessary, suitably located devices for the detection and alarm of carbon monoxide."

Regulation 6(6), Housing (Standards for Rented Houses) Regulations 2019 (S.I. No. 137 of 2019)

The same Regulations require more than an alarm. A landlord must provide for the safe removal of fumes and products of combustion to the outside air, and must ensure that a heat-producing appliance has an adequate air supply for combustion and a properly working flue. Appliances must be kept in a safe condition and in good working order, and installations for gas, oil, and electricity must be maintained in good repair and safe working order. In practice, "where necessary" is understood to mean wherever a fuel-burning appliance is present, and a carbon monoxide alarm is expected to meet the I.S. EN 50291 standard and carry the CE mark.

Alongside the rental standards, the Building Regulations require carbon monoxide detection where a new or replacement combustion appliance is installed in a dwelling. This came from the Building Regulations (Part J Amendment) Regulations 2014 and the accompanying Technical Guidance Document J, in effect since 1 September 2014. That requirement applies to dwellings rather than to hotels and other non-domestic buildings, which is one reason short-stay accommodation is usually approached through the occupier's duty rather than the rental standards.

Enforcement matters for a claim. Local authorities inspect rented properties and can serve Improvement Notices and Prohibition Notices, and can prosecute a landlord who breaches the standards. Where a local authority has recorded a breach of the carbon monoxide requirements, that documented breach provides strong support for a civil claim by an injured tenant.

Proving a carbon monoxide claim

A carbon monoxide claim rests on four elements, and the two central pieces of evidence are the appliance itself and a prompt medical test. To succeed, a claim generally has to establish four things: that the responsible party owed you a duty of care, that they breached it, that the breach caused your carbon monoxide exposure, and that you suffered injury as a result. In a rented home or workplace that duty is usually straightforward, so most carbon monoxide claims turn on breach and causation, which is where evidence matters most.

You may be able to make a carbon monoxide claim in Ireland where the following broadly apply:

• you were exposed to carbon monoxide from a fuel-burning appliance, flue, or ventilation fault;
• another party, such as a landlord, occupier, installer, or employer, owed you a duty of care;
• that party failed to take reasonable care, for example by not servicing an appliance, not providing an alarm where required, or ignoring a reported fault;
• that failure caused your exposure and a diagnosable injury; and
• you are within the time limit for bringing a claim.

The claim is usually brought by the injured person. Where the injured person is a child, a parent or guardian brings it on their behalf, and where an adult cannot manage their own affairs, a next friend may act for them. Where carbon monoxide has caused a death, dependent family members may bring a claim. Carbon monoxide leaves little visible trace, so a claim is built from medical evidence of exposure and independent engineering evidence of the fault. The steps below matter most in the hours and days after a suspected leak.

1. Get fresh air and seek urgent medical attention. Ask the treating doctor to test for carbon monoxide, ideally a carboxyhaemoglobin blood test, as soon as possible, because levels fall once a person is away from the source.
2. Do not let anyone repair, replace, or remove the appliance, flue, or ventilation until it has been independently inspected and photographed. Preserving it prevents a later dispute about what was wrong.
3. Arrange an independent engineer's report, from a Registered Gas Installer for gas, or an equivalent qualified person for oil or solid fuel.
4. Take dated photographs of the appliance, any staining or sooting, condensation, and vents, and note who else, including any pets, was affected and when symptoms began and eased.
5. Keep any record of earlier complaints to the landlord or manager, such as texts, emails, or repair logs, and request any service and alarm records.
6. Consider a formal complaint to the local authority, which can inspect the property and serve a notice.

Each item has a purpose. The timing of the medical test affects proof of exposure, preserving the appliance prevents an argument that the evidence was lost, and the engineer's report supplies independent proof of the defect or breach. Our general guidance on how to prove a public liability claim and on medical evidence explains how these strands come together.

How a carbon monoxide claim works

Most carbon monoxide claims start with the Injuries Resolution Board, and go to court only if they are not resolved there. Personal injury claims in Ireland, other than medical negligence, generally begin with the Injuries Resolution Board rather than in court. In outline, the process runs as follows.

1. Notify the party you hold responsible, in writing, within one month of the incident.
2. Submit an application to the Injuries Resolution Board, supported by a medical report describing your injury.
3. The Board notifies that party, who has 90 days to agree to the claim being assessed.
4. If they agree, or do not respond within the 90 days, the Board assesses the claim; if they refuse consent, the Board issues an authorisation allowing you to bring the claim in court.
5. If the claim is assessed, both sides can accept or reject the assessment; if either rejects it, the Board issues an authorisation to court.

Carbon monoxide claims are often more complex than a routine injury claim, because liability may be disputed or shared among a landlord, an installer, and a product manufacturer, and because the medical picture can take time to settle. Complex claims of this kind are frequently authorised to proceed to court rather than assessed by the Board. Once a complete application is acknowledged, the two-year limitation period is paused while the claim is with the Board. Our guide to the Injuries Resolution Board explains each stage in detail.

Injuries and long-term effects

Carbon monoxide can cause lasting harm well beyond the initial exposure. Acute poisoning can cause headaches, dizziness, nausea, confusion, loss of coordination, collapse, and, at high levels, death. What makes carbon monoxide significant for a claim is that damage can continue after the exposure ends. The HSE recognises that longer-term or repeated low-level exposure can cause memory problems, difficulty concentrating, loss of vision, hearing loss, and, rarely, parkinsonism.

Severe oxygen starvation of the brain can cause a hypoxic brain injury, and some people develop delayed neurological effects that emerge or worsen in the weeks after apparent recovery. Where the injury is serious, the claim may involve neurological and neuropsychological evidence, and its value is assessed by reference to that lasting harm rather than the moment of exposure. Our guides on brain injury claims and, in the most serious cases, acquired brain injury deal with these consequences, and a frightening near-fatal incident can also give rise to a psychological injury claim.

Fatal cases

Where a death has occurred, a dependant's claim may follow, and an inquest may examine the cause. In the most serious cases, carbon monoxide poisoning is fatal. Where a person has died, close family members who were financially dependent on them may be able to bring a claim under the fatal injury provisions of Irish law, and a coroner's inquest will often examine how the death came about. These are difficult circumstances, and the process is handled sensitively. The fatal injury claims guide, along with the pages on dependency claims and inquests, explains how a fatal claim works and who can bring one.

Compensation

Compensation reflects both the injury itself and the financial losses it causes. A carbon monoxide claim is generally made up of two parts. General damages compensate for the pain, suffering, and loss of amenity caused by the injury. Special damages compensate for financial losses and expenses, which in a carbon monoxide case can include medical and rehabilitation costs, care, loss of earnings, and the cost of home adaptations where a lasting neurological injury requires them. In a fatal case, a claim can include the dependants' loss of financial support together with a statutory payment for mental distress.

The amount depends entirely on the nature and severity of the injury and the losses actually suffered, so figures are not set out here. Where an injured person is found to have contributed to their own harm, for example by disabling a working alarm or ignoring a known fault, compensation can be reduced to reflect their share of responsibility, a principle known as contributory negligence. Our general guidance on general and special damages explains how these heads of loss are assessed.

Time limits

A claim is generally subject to a two-year limit, but the clock can start later for hidden effects. Personal injury claims in Ireland must usually be brought within two years, running from the date of the incident or from the later "date of knowledge", the point at which a person first reasonably knew they had a significant injury caused by another's fault. Date of knowledge is particularly important in carbon monoxide cases, because low-level exposure is often misdiagnosed as a viral illness and the connection to a faulty appliance may only become clear later, sometimes once neurological or psychological effects are diagnosed.

Different timing rules apply to children and to fatal cases, and the two-year period is not the same as the process for starting a claim. Because the date of knowledge can be contested, it is wise to take advice early. Our guide on the time limit for public liability claims sets out how the two-year rule and the date of knowledge work in practice.

Much online guidance on carbon monoxide claims is written for the UK and does not apply here. Many first-page results come from UK firms, and the rules they describe are different from Irish law. The table below sets out the points that most often catch people out.

Frequently asked questions