Carbon monoxide and the alarms that warn you

Carbon monoxide gives you nothing to notice. The Health and Safety Executive (HSE), Great Britain's regulator for gas safety, calls it "a colourless, odourless, tasteless, poisonous gas",¹ and in the US the Consumer Product Safety Commission (CPSC) estimates it killed 274 people in 2022 in incidents not caused by fire that involved the consumer products it regulates.⁴ Most people's answer is to buy an alarm, and this lesson does tell you where each country's rules put one. But England's own building guidance says an alarm "should not be regarded as a substitute for the correct installation and regular servicing of combustion appliances",⁷ and that sentence runs through everything below: the alarm is the last protection, not the first.

The callout's gas steps are for a gas smell. A carbon monoxide alarm going off, or a person who feels ill indoors, is a different emergency, and First Aid and CPR has already taught it: lesson 2, "Danger, the call, and recognising cardiac arrest", gave you carbon monoxide's signs and getting outside to call, and lesson 14, "Seizures, low blood sugar and poisoning", gave each country's response. This lesson doesn't repeat either. It deals with the house: where the gas comes from, what keeps it from being made, and where the alarms go. Two sections below state law, and they carry this label in short; here it is in full. This is general information, not legal advice. The rules differ between England, Wales, Scotland and Northern Ireland, and between US states and cities, and they change.

Where carbon monoxide comes from

HSE puts the mechanism in two sentences. Carbon monoxide is "produced by incomplete burning of carbon-based fuels, including gas, oil, wood and coal", and "Carbon-based fuels are safe to use. It is only when the fuel does not burn properly that excess CO is produced, which is poisonous."¹ So every appliance that burns something is a possible source: a boiler, a furnace, a gas fire, a wood burner, a water heater, a cooker, and anything with an engine. The fuel isn't the problem. The burning going wrong, or the fumes having nowhere to go, is.

CPSC adds two facts that explain why this gas kills people who would have run from smoke. The first is that it gives no warning. Petrol (gasoline) engines "may not emit an irritating exhaust smoke, even though they produce large amounts of CO", and badly vented gas appliances "may emit potentially lethal amounts of CO without any irritating fumes to alert potential victims to the danger."⁴ The second is speed. Carbon monoxide binds to haemoglobin, the oxygen carrier in blood, with "an affinity about 250 times that of oxygen", and with the fast-rising levels an engine produces, "sudden extreme hypoxia can result in rapid incapacitation and loss of consciousness, which prevent exposed individuals from leaving the hazardous environment."⁴ With engine exhaust, on CPSC's account, people can lose the ability to leave before they know there's anything to leave.

What the numbers count

In the US. CPSC's 2022 report estimates 274 deaths from carbon monoxide not caused by fire and involving consumer products "under the CPSC’s jurisdiction". Of those, 64% happened in a home location, and across 2020 to 2022, 59% came in the four cold months of November to February.⁴ The report leaves out fires, motor vehicles alone, work, and intentional deaths, and by its own measure its 2022 data are about 90% complete. The Centers for Disease Control and Prevention (CDC) gives a larger number, "more than 400 Americans" a year dying from carbon monoxide not linked to fires.⁶ The two don't conflict. Both leave out fires and deliberate deaths, but CDC's count isn't limited to particular products, and its list of sources includes cars and trucks; CPSC counts only the products it regulates and leaves out deaths from a motor vehicle alone.

The CPSC table for 2022, by the product involved:⁴

The last row is this course's addition of CPSC's three smallest rows. Two rows are worth a second look. Charcoal and gas ranges aren't heaters, and CPSC names both among the devices, not designed for heating, that were known or suspected to have been used to heat an enclosed space where someone died.⁴

In Great Britain. HSE's carbon monoxide page says: "According to the HSE statistics every year around 7 people die from CO poisoning caused by gas appliances and flues that have not been properly installed, maintained or that are poorly ventilated."¹ Its general gas FAQ gives the same "around 7".² Neither gives a year. The statistics page the carbon monoxide page links to holds HSE's table of gas incidents reported under RIDDOR, the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013. Regulation 11(1) puts the duty on "a conveyor of flammable gas through a fixed pipe distribution system", which in plain terms is a company that pipes gas, and on "a filler, importer or supplier (except by retail) of a refillable container containing liquefied petroleum gas". Once one of them is told of "the death, loss of consciousness or taking to hospital of a person because of an injury arising in connection with that gas", it has to report it to HSE.¹⁸

HSE says its table's figures have been confirmed as an accurate count of deaths from domestic gas incidents, mainly piped gas but bottled gas too.³ The carbon monoxide page, for its part, still gives an NHS Direct phone number that no longer runs, so some of its content is older than its 2026 date, and this course couldn't find the year behind its "around 7" or what it counts. So this lesson gives you both numbers with their sources: HSE's table, and the undated figure on HSE's own pages. Neither counts carbon monoxide from wood, coal, oil or engines.

The order of protection

The order below is this course's, built on two things the sources say: England's building guidance says an alarm is no substitute for correct installation and regular servicing, and HSE says alarms are no replacement for maintenance and safety checks.⁷² The alarm comes last.

1. The appliance is installed correctly. For gas in Great Britain, HSE's and the Gas Safe Register's advice is a Gas Safe registered engineer, and lesson 10, "Gas: the law and the engineer", has the law and how to check one. Call someone.
2. It is serviced every year. HSE "strongly advises that gas appliances and/or flues are regularly checked for safety at least once every 12 months".² For oil, wood and coal, HSE says to make sure the appliance "is serviced and maintained by a competent person and the chimney is regularly swept."¹ In the US, CDC: "Have your heating system, water heater, and any other gas, oil, or coal burning appliances serviced by a qualified technician every year."⁶ Servicing is Call someone; booking it is yours, or in a let home in Great Britain your landlord's (lesson 10).
3. The flue or chimney is clear. The next section.
4. The air it needs isn't blocked. The Energy Saving Trust, the UK's government-funded energy advice body, warns people draught-proofing their homes: "You must not block fixed ventilation openings needed for flueless or open-flue gas heaters."¹⁶ EST doesn't explain the two kinds of heater there, and this course read no definition of them; the point EST makes is that those fixed openings are there for the appliance. That is the only ventilation advice this course read for combustion appliances; England's building guidance on ventilation is longer and this course didn't read it.
5. Then an alarm. HSE "strongly recommends the use of CO alarms as one useful precaution to give advance warning of CO in a property", and says they "should not be regarded as a replacement for regular maintenance and safety checks by a Gas Safe registered engineer."²

Why last? An alarm measures carbon monoxide that's already in the room. The first four steps stop it being made or keep it going up the flue. That reasoning is this course's own, from what an alarm is. CDC's own list puts detectors first on the page, and neither CDC nor CPSC ranks the steps.

What you can see at the appliance

HSE lists signs "which indicate incomplete combustion is occurring and may result in the production of CO":¹

• "yellow or orange rather than blue flames (except fuel effect fires or flueless appliances which display this colour flame)"
• "soot or yellow/brown staining around or on appliances"
• "pilot lights that frequently blow out"
• "increased condensation inside windows"

Looking for them is Yours: eyes only, no panels off. What you do about one isn't. In Great Britain, HSE's steps if you think an appliance is spilling carbon monoxide are to "Call the National Gas Emergency Service on 0800 111 999", to "Switch off the appliance and shut off the gas supply at the meter control valve", and to "Open all doors and windows to ventilate the room".¹ Lesson 1 showed you where that valve is. In the US, this course read no utility's steps for a suspected spillage, so a US reader follows First Aid and CPR lesson 14 if anyone feels ill, and calls a qualified technician for the appliance.

In a US home with a forced-air furnace, lesson 7, "Heating: boilers, radiators and furnaces", gave the Department of Energy's point that a leaking heat exchanger mixes combustion gases with the air you breathe, which is one reason the annual service is a professional's. CDC adds one check you can make by eye on a water heater or furnace: "Horizontal vent pipes for appliances, such as a water heater, should go up slightly as they go toward outdoors", which "prevents CO from leaking if the joints or pipes aren't fitted tightly."⁶ A pipe that runs level or dips is a question for the technician, not something to adjust.

Chimneys and flues

A blocked chimney or flue can let carbon monoxide build up inside the home, as CDC puts it below.⁶ The two countries' advice on how often to deal with it differs, and each is given here as its own source gives it.

CDC says the same in one line: "Have your chimney checked or cleaned every year. Chimneys can be blocked by debris, which can cause CO to build up inside your home or cabin."⁶ HETAS's page also gives a reason besides carbon monoxide: 2,608 chimney fires in England between April 2021 and March 2022, which it calls a 16% fall on the year before.¹⁴ Sweeping is Call someone, and HETAS's advice for checking the sweep is short: "Always ask to see identification before a sweep carries out any work."¹⁴ Going up on the roof to look is not part of this course.

Never indoors

Every source on this section is American: this course read no UK guidance on generators, so the distances below are US advice.

• Generators. CPSC: "Never use portable generators inside homes or garages, even if doors and windows are open. Use generators outside only, at least 20 feet away from homes with exhaust facing away."⁵ CDC puts it as "more than 20 feet away from any windows, doors, and vents", and says to run a battery-powered or battery backup CO detector in the home while the generator is on.⁶ Twenty feet is about 6 metres, by this course's conversion. CPSC gives a sense of scale: "one portable generator can produce the same amount of carbon monoxide as hundreds of cars."⁵
• A gas oven for heat. CDC: "Never heat your house with a gas oven."⁶
• Charcoal and camp stoves. CDC: "Never burn charcoal indoors." and "Never use a portable gas camp stove indoors."⁶
• A car in an attached garage. CDC: "Never run your car or truck inside a garage that is attached to a house, even with the garage door open."⁶ The car itself is Car Basics' subject, next on the Core; the garage joined to your house is this course's.

Why doesn't an open door fix it? CPSC gives no airflow calculation. What it gives is the scale above, the speed at which people are overcome, and a rule written with the open door already in it, which is the part to remember when the weather makes the garage tempting.

Two homes, two countries

This is general information, not legal advice.

An end-terrace in Lancashire

This is the simple case. An owner-occupied end-terrace in Lancashire has a gas combi boiler on the kitchen wall, replaced in 2024, and a gas cooker in the same kitchen. The two bedrooms are upstairs. Nothing else burns fuel.

1. Which rule? The house isn't let, so the landlord regulations below don't reach it. The boiler was a replacement fixed gas appliance fitted after 1 October 2022, so England's requirement J3 applies to that installation, and Approved Document J, the government's guidance on meeting it, says "a carbon monoxide alarm should be provided in the room where the appliance is located."⁷¹⁷ That is the kitchen.
2. The cooker. The same paragraph excludes "gas appliances used solely for cooking".⁷ The cooker adds nothing to the alarm rule. It still burns gas, and it still gets its annual check, which HSE advises for gas appliances at least once every 12 months.²
3. Where in the kitchen. On the ceiling at least 300 mm (about 12 inches) from any wall, or on a wall as high up as possible, above any doors and windows, but not within 150 mm (about 6 inches) of the ceiling, and "between 1m and 3m horizontally from the appliance" (about 3 to 10 feet; the inch and foot figures are this course's conversions).⁷
4. What kind. One that complies with BS EN 50291-1 and is powered by a battery made to last the alarm's working life, with a warning when that life is running out. A mains-wired alarm with fixed wiring and a sensor failure warning is allowed instead, but not a plug-in one.⁷ A mains-wired alarm is an electrician's job, and this course teaches no wiring.
5. The order still runs first. The boiler's annual service by a Gas Safe registered engineer, the flue outside kept clear, the vents left open.

One more point is this course's own reading, not a rule: the guidance puts the alarm by the boiler, not by the beds. Whether that kitchen alarm is loud enough upstairs with the doors shut is something the owner can find out by pressing its test button with someone listening in a bedroom. If it isn't, a second alarm near the bedrooms is a reasonable addition, which is roughly where US advice would have put one in the first place.

An ice storm in Indiana, with a gap for you

This is the harder case. An ice storm has cut the power to a family's house in Indiana, and the utility says it could be three days. They've borrowed a portable generator. The plan: run it in the attached garage "with the big door open, so it's out of the ice", with a lead through the kitchen door to the fridge and a heater. The grandmother, cold in the back room, suggests lighting the charcoal grill in the enclosed back porch, "just to take the edge off".

The generator is the obvious problem, and it's taken first below. There's a second hazard in the plan. Find it, and say which source rules it out, before you open the answer.

Carbon monoxide alarms: the law and the advice, by place

This is general information, not legal advice.

The rules differ more here than anywhere else in this lesson, and not only between the two countries. Each set below is given as its own authority gives it.

England

Landlords. The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 require a landlord of a tenancy they cover to make sure that "a carbon monoxide alarm is equipped in any room of the premises which is used wholly or partly as living accommodation and contains a fixed combustion appliance other than a gas cooker".⁸ A bathroom or lavatory counts as living accommodation, and "room" includes a hall or landing. Each alarm must be checked to make sure it is "in proper working order on the day the tenancy begins if it is a new tenancy", and an alarm a tenant reports as faulty (on a report made since 1 October 2022) must be "repaired or replaced".⁸ If you rent in England, that's what you can expect, and the landlord is the person to tell.

New or replacement appliances. England's building regulations carry a requirement, J3, which is law. In the Building Regulations 2010 it reads: "Where a combustion appliance is provided, appropriate provision having regard to the design and location of the appliance shall be made to detect and give early warning of the release of carbon monoxide at levels harmful to persons." It "applies only to fixed combustion appliances located in dwellings."¹⁷ Approved Document J is the government's guidance on how to meet it. It prints J3 in shorter words of its own, "Where a fixed combustion appliance is provided, appropriate provision shall be made to detect and give warning of the release of carbon monoxide", and it asks for an alarm in the same room when a new or replacement fixed appliance is installed: solid fuel since the 2010 edition, and gas and oil since amendments that "come into effect on 1 October 2022". Gas appliances used solely for cooking are excluded. The siting and the kind of alarm are the ones in the Lancashire example.⁷

Those are the two situations the rules this course read for England cover. It read no rule that asks an owner-occupier to add an alarm to an appliance already in place.

Scotland

Scotland's rule covers every home, whoever owns it. An order made in 2019 added two things to the tolerable standard, the standard every house must meet under the Housing (Scotland) Act 1987, including "satisfactory equipment installed for detecting, and for giving warning of, carbon monoxide present in a concentration that is hazardous to health", and after a later amendment it took effect on 1 February 2022.⁹ The Scottish Government's factsheet says what that means in practice: "If you have a carbon-fuelled appliance like a boiler, open fire or wood burner, you must also have a carbon monoxide detector in the same room. This does not need to be linked to the smoke alarms." And: "Gas cookers and hobs do not need a carbon monoxide detector."¹⁰ A battery-powered one "must have a sealed battery for the duration of its lifespan", and the standard it names is "British Kitemark EN 50291-1" (HSE gives a Kitemark as an example of a British or European approval mark).¹⁰² Meeting it is, in the factsheet's words, "the property owner’s responsibility".¹⁰

Wales and Northern Ireland

This course didn't read either nation's alarm rules, so it states none. If you live in Wales or Northern Ireland, ask your council what applies, or your landlord if you rent.

The US

There is no federal rule in what this course read. The National Conference of State Legislatures (NCSL), which tracks state law for legislators, says: "Most states have adopted requirements mandating the use of carbon monoxide detectors. These requirements may come from statute, regulation or code requirement."¹¹ Its own table carries a warning that it "may not be reflective of all requirements", and it sends homeowners to their "state or local housing department".¹¹ Two statutes, read on the states' own sites, show how far apart the rules can be.

• Minnesota puts the alarm by the beds, in section 299F.51. "Every single-family dwelling and every dwelling unit in a multifamily dwelling must have an approved and operational carbon monoxide alarm installed within ten feet of each room lawfully used for sleeping purposes."¹³ (Ten feet is about 3 metres.) It also says: "No person shall remove batteries from, or in any way render inoperable, a required carbon monoxide alarm."¹³
• California puts the condition on the house, in Health and Safety Code section 17926. The owner must install a device "approved and listed by the State Fire Marshal", and "in each existing dwelling unit having a fossil fuel burning heater or appliance, fireplace, or an attached garage", and as to placement, "in a manner consistent with building standards applicable to new construction for the relevant type of occupancy or with the manufacturer’s instructions, if it is technically feasible to do so."¹² This course didn't read those building standards.

The course's question, law or advice, whose, and where?, applies to summaries too. NCSL's one-line version of the California law says it "Requires the owner of every single family dwelling ... to maintain a carbon monoxide device", with no mention of the fuel appliance, fireplace or garage that the statute itself makes the trigger.¹¹¹² A summary is where to start looking. The statute is where the rule is.

The advice, which isn't law. CPSC: "Install battery-operated CO alarms or CO alarms with battery backup on every level of the home and outside sleeping areas. Interconnected CO alarms are best; when one sounds, they all sound."⁵ CDC: "Install battery-operated or battery back-up CO detectors near every sleeping area in your home."⁶

Side by side

The English and Scottish rules place the alarm by the thing that makes the gas. The US advice, and Minnesota's law, place it by the people who might breathe it. No source this course read explains why the two countries chose differently, so this lesson gives no reason. Neither is wrong. Each is the rule or the advice where it applies.

First Aid and CPR lesson 14 put its prevention point this way: "the NHS advises a carbon monoxide alarm in every room with an appliance that burns gas, oil, coal or wood." That is the NHS's advice, not a legal rule. The rules are narrower in both UK nations whose rules this course read: the English landlord rule and building guidance, and the Scottish Government's explanation of its standard, all leave gas cookers out, and England's rules reach only let homes and new or replacement appliances. The US advice is organised by floors and bedrooms rather than rooms with appliances. So the refinement is this: the NHS line tells you where the risk is, and your own nation's or state's rule tells you what's required.

Buying one, and how long it lasts

This course names no product. It describes alarms by the standard the rule names: BS EN 50291-1 in England's building guidance and in Scotland, and HSE advises checking that an alarm "complies with British Standard EN 50291 and carries a British or European approval mark, such as a Kitemark."⁷¹⁰² Minnesota's statute defines an approved alarm as one certified by a testing laboratory "to conform to the latest Underwriters Laboratories Standards (known as UL2034 standards)"; this course read the statute, not the standard.¹³ CPSC's carbon monoxide page lists recent warnings to stop using particular plug-in gas and carbon monoxide detectors that failed to alert to carbon monoxide, and particular combination smoke and carbon monoxide detectors that failed to warn of smoke and fire.⁵ The Scottish Government says "There is no list of approved suppliers or fitters. We cannot endorse or recommend specific products or suppliers."¹⁰

Alarms wear out. CDC: "Replace your CO detector following the manufacturer's instructions or every 5 years."⁶ Approved Document J asks for a warning "when the working life of the alarm is due to pass".⁷ Testing a carbon monoxide alarm by its button, as its maker's instructions say, is Yours.

What people get wrong

"The carbon monoxide alarm means the boiler doesn't need servicing." England's building guidance says the opposite in terms, and HSE says alarms are not "a replacement for regular maintenance and safety checks".⁷²

"With the garage door open, the generator's fine." CPSC and CDC both rule out a garage "even if doors and windows are open".⁵⁶

"Take the battery out if the carbon monoxide alarm keeps going off." In Minnesota, removing the battery from a required alarm is against the law set out above.¹³ An alarm that sounds is First Aid and CPR lesson 14's emergency first, and a fault second.

"Replaceable-battery detectors are fine in Scotland." A battery carbon monoxide detector there "must have a sealed battery for the duration of its lifespan".¹⁰

"Carbon monoxide alarms last forever." CDC says replace them by the maker's instructions or every five years, and England's building guidance asks for a warning when an alarm's working life is running out.⁶⁷

"Every room with a burning appliance legally needs an alarm." It's the NHS's advice, not a legal rule. England's landlord rule and building guidance, and the Scottish Government's factsheet, leave out gas cookers, and in England the rules reach only let homes and new or replacement appliances.⁸⁷¹⁰

Practice

For your plan

This lesson adds to the calendar: each carbon monoxide alarm tested by its button as its maker says, and its replace-by year; each fuel-burning appliance serviced every year; each chimney swept or inspected as HETAS or CSIA advises for your fuel. It adds to the map: every fuel-burning appliance and its room, and every carbon monoxide alarm. It adds to the stop list: any of HSE's four signs at an appliance, a generator anywhere but outside and at least 20 feet off, charcoal burned indoors, a gas oven used for heat, and a carbon monoxide alarm going off, which goes straight to First Aid and CPR lesson 14's response.

Connections

Lesson 1, "How a house works, and where it switches off", said the way out for combustion products has no switch to find, and this lesson has been about keeping its way out working. Lesson 7, "Heating: boilers, radiators and furnaces", gave the heat exchanger and the annual service, and lesson 10, "Gas: the law and the engineer", covers the law on who may work on a gas appliance and the engineer's card. First Aid and CPR lessons 2 and 14 hold the signs and the response, and nothing here replaces them. The smoke alarm routine, and what England's fire figures say about why alarms stay silent, comes next, in lesson 12. Lesson 18, "Damp inside: condensation, mould, ventilation and rising damp", will come back to ventilation, where this lesson's advice still holds: never block the air a fuel-burning appliance needs. Car Basics, next on the Core, takes the car that this lesson only kept out of the garage.

Go deeper

• Approved Document J, the 2022 PDF, free. This course read requirement J3 and the carbon monoxide alarm paragraphs, not the whole document. Paragraphs 3.43 to 3.45 are England's guidance for a new gas boiler.
• Scottish Government, "Fire and smoke alarms: the law", free. Read here: its two sections on what each home needs and what to buy. What one nation's rule asks of every home, owned or rented.
• CPSC, "Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products: 2022 Annual Estimates", May 2026, free. Read here: the summary, the introduction and Table 1. Table 1 shows eleven years of deaths by product, and the introduction explains why engines are dangerous.

Sources

1. Health and Safety Executive, "Gas safety - Carbon monoxide awareness frequently asked questions". Read: full text; re-read on the live page 25 September 2026. The page is stamped 2026 but still gives an NHS phone number that no longer runs, so its content dates are uncertain; its "around 7" has no year.
2. Health and Safety Executive, "Domestic gas: frequently asked questions". Read: the carbon monoxide alarm, servicing and landlord passages, re-read 25 September 2026; the page was searched, not read whole.
3. Health and Safety Executive, "RIDGAS: Gas-related incidents reported under RIDDOR in Great Britain", published 20 November 2025. Read: the contents, notes and Table 1 in full. 2024/25 is provisional.
4. John Topping, US Consumer Product Safety Commission, "Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products: 2022 Annual Estimates", May 2026. A staff report, not reviewed or approved by the Commission. Read: the executive summary, the introduction, the national estimates and product category sections, and Table 1.
5. US Consumer Product Safety Commission, "Carbon Monoxide Information Center", read from Internet Archive capture 20260908150612 (the live page refuses automated readers). Read: full text.
6. Centers for Disease Control and Prevention, "Carbon Monoxide Poisoning Basics", 12 January 2026, read from Internet Archive capture 20260920191925 (the live page refuses automated readers). Read: full text.
7. HM Government, Approved Document J: Combustion appliances and fuel storage systems, 2010 edition incorporating 2010, 2013 and 2022 amendments, England. Read: requirement J3 and its limit, the summary of the 2022 changes, and paragraphs 2.34 to 2.36, 3.43 to 3.45 and 4.30 to 4.32; re-read 25 September 2026. The ventilation sections were not read.
8. The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 (SI 2015/1693), regulation 4, as amended. Read: in full on the live page, 25 September 2026. England; landlords of the tenancies the Regulations cover.
9. The Housing (Scotland) Act 1987 (Tolerable Standard) (Extension of Criteria) Order 2019 (SSI 2019/8), and its article 1 as amended by SSI 2021/46. Read: the order as made in full, and article 1 as amended, 25 September 2026. Scotland.
10. Scottish Government, "Fire and smoke alarms: the law", last updated 14 August 2024. Read: the sections "What each home needs" and "Where and what to buy" in full, re-read 25 September 2026.
11. National Conference of State Legislatures, "Carbon Monoxide Detector Requirements, Laws and Regulations". Read: the introduction, the note, and the rows for California, Illinois, Massachusetts, Minnesota, New York and Texas.
12. California Health and Safety Code section 17926. Read: the whole section on the state's site, 25 September 2026.
13. Minnesota Statutes 2025, section 299F.51 and section 299F.50 (definitions). Read: both sections in full on the Revisor's site, 25 September 2026.
14. HETAS, "When should I get my chimney swept?". Read: full text, re-read 25 September 2026.
15. Chimney Safety Institute of America, "Homeowner Resources". Read: full text, re-read 25 September 2026. NFPA 211 itself was not read; it is quoted as CSIA quotes it.
16. Energy Saving Trust, "Draught proofing", read from Internet Archive capture 20260916151311 (the live site refuses automated readers). Read: full text. Its savings figures are not used.
17. The Building Regulations 2010 (SI 2010/2214), Schedule 1, Part J, requirement J3 and its limit. Read: Part J on the live page, revised text, 26 September 2026. England.
18. The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013 (SI 2013/1471), regulation 11. Read: regulation 11 in full on the live page, 26 September 2026. Great Britain.