Angithis, heaters and gas geysers: how to stay safe from carbon monoxide this winter

In short: Carbon monoxide is a gas you cannot see or smell. In Indian winters it builds up when an angithi, coal or wood heater, gas geyser or car engine burns in a closed space. Never sleep with a fire in the room, keep gas geysers out of bathrooms, and if anyone gets a headache, dizziness or confusion, get everyone into fresh air and call 112.

Every winter, the same news story runs in North India with different names. In January 2024, Delhi’s fire service said 15 people had died in the city that month after sleeping in closed rooms with an angithi, a coal brazier, and that the toll passed 20 once the rest of the National Capital Region was counted. In the first week of January 2025, Jammu and Kashmir reported 11 deaths from suffocation in a single week, including a family of five in one rented room in Srinagar.

These are not freak accidents. They are carbon monoxide poisoning, and it is almost entirely preventable. Yet most of what you will find about it online is either a news report after a death or advice written for American homes with central heating. This guide is for Indian homes: the angithi and the sigri, the bukhari and the kangri, the LPG geyser in a small bathroom, the car parked with its engine running for warmth. It explains what the gas does, who is most at risk, the early signs, what to do in the first minutes, and the habits that keep a family safe.

What is carbon monoxide, and why can’t you sense it?

Carbon monoxide (CO) is a gas made whenever a fuel burns without enough oxygen: coal, charcoal, wood, cow-dung cakes, kerosene, LPG, piped gas, petrol or diesel. India’s National Disaster Management Authority (NDMA) describes it as colourless, odourless and tasteless. That is the whole danger. Smoke can make your eyes water, but the CO that comes with it gives no warning of its own, and a bed of glowing coals with no visible smoke can still be giving it off.

Once breathed in, CO takes the place of oxygen in the blood, so the brain and heart are starved of oxygen even though the person is breathing normally. The US Centers for Disease Control and Prevention (CDC) warns that people who are asleep, or who have been drinking, can die before they ever notice a symptom. That is why so many Indian cases are found in the morning.

Worldwide, a study from the Global Burden of Disease project estimated that unintentional CO poisoning killed about 28,900 people in 2021, nearly 70% of them men. The global death rate fell by more than half between 2000 and 2021, and the authors call the remaining deaths almost entirely preventable, through safer heating and cooking devices, cleaner generators and carbon monoxide alarms.

Where does carbon monoxide come from in Indian homes?

Two autopsy studies from the All India Institute of Medical Sciences (AIIMS) in New Delhi show the pattern clearly. The first looked at 40 deaths between 2010 and 2015: about 80% happened in winter, most often in January, and in every case but one the victim was in a closed room or space with the source nearby. The second, covering 56 deaths over fifteen years, found that 95% happened in winter, that most victims were aged 21 to 30, and that the most common source was coal burning in earthen or iron vessels used to heat a room.

The usual sources are:

• Angithis, sigris and coal or charcoal braziers brought indoors to warm a room, especially when doors and windows are shut for the night.
• Bukharis and wood or coal stoves in the hills, where a short or leaky chimney lets fumes back into the room, and the kangri fire pot in Kashmir. NDMA’s cold-wave guidelines name these open fire pots directly as a cause of CO deaths in closed rooms.
• LPG gas geysers in bathrooms without a flue or ventilation (more on this below).
• Cars with the engine running in a closed garage or basement, or as a place to sleep for warmth. The AIIMS series included deaths inside cars with the engine on, and NDMA advises never to sleep in a vehicle with the engine running.
• Diesel or petrol generators, gas stoves and kerosene heaters used in small, closed rooms, shops, tents or site huts.
• House fires. Smoke from any fire is full of CO. An electric heater does not burn fuel and so does not make CO itself, but one left near a quilt can start a fire.

The bathroom faint: gas geyser syndrome

Indian neurologists have a name for a pattern they see every winter: gas geyser syndrome. A person, often young and healthy, collapses or has a fit while bathing in a small, closed bathroom with an LPG geyser running.

At Sir Ganga Ram Hospital in New Delhi, doctors documented 26 such cases over two years. Eleven looked like seizures, 13 were CO poisoning (four of them close to cardiac arrest), and two triggered epilepsy. On follow-up, four of the CO patients had subtle problems with thinking and two developed early features of Parkinsonism. At MS Ramaiah Medical College in Bengaluru, a review of 24 people who lost consciousness while bathing with a gas geyser found that 21 recovered on their own, two were found dead in the bathroom and one died within a week.

Because the person wakes up and seems fine, these episodes are easy to mistake for a simple faint or for epilepsy. A 2025 report in the Indian Journal of Public Health again called for strict installation rules and proper ventilation. The gas distributor Maharashtra Natural Gas Limited is blunt in its installation guideline: no gas geyser is permitted in a bathroom or a concealed area, because fumes collect and can cause suffocation.

Myths and facts about carbon monoxide

1. Myth: “If there were gas in the room, I’d smell it.”

Fact: CO has no smell. The smell of smoke, or the added smell of LPG, comes from other things. A clean-burning coal bed or a geyser with poor airflow can make CO with nothing to smell.

2. Myth: “Once the coals stop smoking, the angithi is safe to keep in the bedroom.”

Fact: Glowing coals are still burning, and still need oxygen. Whatever burns in a closed room is a risk until it is fully out and outside.

3. Myth: “A bucket of water next to the angithi keeps the air safe.”

Fact: This advice is common, and even shows up in official quotes. A bowl of water may ease dry air, but water does not soak up carbon monoxide. Ventilation, and not sleeping with a fire in the room, are what protect you.

4. Partly true: “Keeping a window open is enough.”

Fact: Ventilation helps, and NDMA and fire officials advise it. But you cannot judge how much fresh air is enough, and wind and closed doors change it through the night. Treat an open window as a minimum, not a guarantee.

5. Myth: “The pulse oximeter reads 98%, so their oxygen is fine.”

Fact: An ordinary fingertip oximeter cannot tell CO from oxygen in the blood. In a study of 124 poisoned patients, oximeters read an average of 99% while the true oxygen level in the blood averaged under 89%. A normal reading proves nothing in suspected CO poisoning.

6. Myth: “She woke up and feels fine, so there’s no need to see a doctor.”

Fact: Some people develop problems with memory, mood or movement days or weeks later. Anyone who fainted, was confused or was hard to wake needs a hospital check.

7. Myth: “It only happens to poor families in villages.”

Fact: The AIIMS victims were mostly young adults in a big city, and gas geyser cases have been reported from homes in Delhi and Bengaluru. Any home that burns fuel indoors is at risk.

Who is most at risk?

Everyone in a closed room breathes the same air, but the CDC says some people are harmed sooner or more badly:

• babies and young children;
• older adults;
• people with heart disease, anaemia or breathing problems such as asthma or COPD;
• pregnant women, because the unborn baby is especially vulnerable. CDC’s clinical guidance tells doctors to test for pregnancy in any woman of childbearing age with suspected CO poisoning, and to have a lower threshold for intensive treatment;
• anyone asleep, drunk or sedated, who will not notice the warning signs.

What are the early signs?

The symptoms are easy to dismiss, which is why they matter. NDMA, the NHS and the CDC list:

• headache, often the first sign;
• dizziness, weakness and tiredness;
• nausea or vomiting;
• confusion, drowsiness or blurred vision;
• shortness of breath or chest pain;
• ringing in the ears;
• in severe poisoning, fainting, fits and loss of consciousness.

You may have read that CO turns the lips “cherry red”. NDMA lists bright red lips, and pathologists describe a cherry-pink colour at autopsy, but in living people it is often absent, and the NHS notes that flushing is harder to see on brown skin. Do not wait for a colour change.

The strongest clues come from the situation, not the symptom:

• more than one person, or a pet, feels ill at the same time;
• the symptoms started after a heater, angithi, geyser or engine was turned on;
• there is no fever, unlike flu;
• people feel better when they go outside, and worse when they come back in. The NHS lists this as a typical sign.

What to do in the first minutes

If you suspect carbon monoxide, act on the suspicion. You do not need proof.

1. Get everyone out into fresh air, now. Carry out anyone who is drowsy. Open doors and windows on the way if you can do so quickly, but do not stay inside to do it.
2. Turn off the source only if it is quick and safe: switch off the geyser or the gas valve, or the car engine. Do not stay in the room to put out an angithi.
3. Call 112 (or 108 for an ambulance) if anyone is unconscious, confused, breathless, has chest pain or had a fit. NDMA advises giving rescue breaths if the person is not breathing; if you know CPR, start it.
4. Lay an unconscious person who is breathing on their side and stay with them until help arrives.
5. Go to a hospital even if symptoms fade. Tell the doctors it may be carbon monoxide, so they can test the blood level.
6. Do not go back in or reuse the heater or geyser until the cause has been found and fixed.

What happens in hospital

The main treatment is oxygen. CDC’s clinical guidance advises 100% oxygen through a mask, usually for about four to five hours or until the person has no symptoms, along with checks of the heart and nervous system. The diagnosis is made with a blood test for carboxyhaemoglobin, the form of haemoglobin that is carrying CO instead of oxygen, since a normal fingertip oximeter cannot detect it.

Some patients with severe poisoning, unconsciousness or pregnancy may be considered for hyperbaric oxygen, which means breathing oxygen in a pressurised chamber. In one US trial, 25% of patients treated this way had thinking problems at six weeks, compared with 46% of those given ordinary oxygen. A Cochrane review of all the trials found the evidence too mixed to be sure of the benefit, and not every hospital has a chamber. Your doctors will decide what is right.

CDC advises a repeat check about two weeks after discharge, and families should watch for new forgetfulness, personality change, poor concentration, trouble walking or stiffness in the weeks after poisoning.

How to keep your home safe this winter

Heating

• Never sleep in a room with a burning angithi, sigri, kangri, bukhari, charcoal stove or kerosene heater. Use it while everyone is awake, put it out completely, and take it outside before bed.
• Keep a window or ventilator open whenever anything burns indoors, and never block air bricks or vents to keep the cold out.
• Check bukhari and stove chimneys before the season, so they are long enough, unblocked and lead fully outside.
• Prefer electric heating where you can. An electric heater, oil-filled radiator or convector makes no CO, but keep it well away from quilts, curtains and clothes, and switch it off when you sleep. NDMA advises turning heaters off when they are not needed.

Gas geysers

• Install the geyser outside the bathroom, in a ventilated area, with a flue to the outside where possible. The MNGL guideline lists the safety features to look for: compliance with IS 15558, a flame failure device and an oxygen depletion sensor.
• If the geyser is already in the bathroom, fill a bucket first, switch the geyser off, and then close the door and bathe. Keep the exhaust fan on and the ventilator open.
• Watch the flame. MNGL says a flame that turns from blue to yellow with black smoke needs a service visit straight away. It also advises servicing the burner every six months and replacing the rubber gas tube every year.
• Never let a child bathe alone in a bathroom with a gas geyser running.

Cars and generators

• Never sleep in a car with the engine running, and never run an engine in a closed garage or basement.
• Keep generators outdoors, well away from doors and windows.

Alarms

• Fit a carbon monoxide alarm in every room with a fuel-burning appliance, as the NHS advises, and in the room where people sleep. Test it regularly and replace the battery when it warns you. The authors of the global study call for alarms to be mandatory for good reason, but an alarm is a backstop, not permission to sleep beside a fire.

Smog is not a reason to seal the room

Many families shut every window in winter because of smog. Our guide to the air pollution season covers how to cope with bad outdoor air, but a sealed room with a fire in it is far more dangerous than a little outside air.

Red flags: get help immediately

Call 112 or go to the nearest emergency department straight away if, after time near a heater, angithi, geyser or running engine, someone:

• is unconscious, very drowsy or cannot be woken properly;
• has had a fit, or has fainted in the bathroom;
• is confused, slurring words or behaving strangely;
• has chest pain, a racing heartbeat or is breathless;
• is pregnant, a baby or an older adult with any symptoms at all.

See a doctor the same day if several people in the house have had headaches, dizziness or nausea that ease when they go outside, even if they now feel better. Then find the source before anyone sleeps in that room again.

The bottom line

Carbon monoxide gives no warning you can see or smell, and in Indian winters it kills people in their sleep, most often young, healthy adults in closed rooms with an angithi or a coal heater. The fix costs almost nothing: never sleep with anything burning in the room, keep gas geysers out of closed bathrooms, never sit in a running car in a closed space, and consider a carbon monoxide alarm. If anyone gets a headache, dizziness or confusion near a fire or a geyser, get everyone into fresh air first and ask questions later.

This article is general health information, not medical advice. If you think someone has carbon monoxide poisoning, get them into fresh air and call 112 or go to the nearest hospital.

Frequently asked questions

How can I tell carbon monoxide poisoning from a cold, flu or an ordinary headache?

You often cannot tell from the symptoms alone, because the US CDC describes them as flu-like: headache, dizziness, weakness, nausea and confusion. The clues are the setting. Suspect carbon monoxide if several people or pets in the same room feel ill at once, if the symptoms began after a heater, angithi, geyser or engine was running, if there is no fever, and if you feel better after going outside. When in doubt, get everyone into fresh air first and then seek help.

Is an angithi safe if I keep a window slightly open?

It lowers the risk but does not remove it. Fire officials and India's NDMA advise ventilation, and a gap in the window is far better than a sealed room. But there is no way to know how much air is enough without a carbon monoxide alarm, and most of the deaths in Indian studies happened in closed rooms, often to people who were asleep. The safer rule is to use the angithi only while everyone is awake, then put it out completely and carry it outside before anyone goes to sleep.

Can a gas geyser be installed inside the bathroom?

It should not be. Maharashtra Natural Gas Limited's installation guideline says no gas geyser is permitted in a bathroom or concealed area, because fumes can collect and cause suffocation. It recommends a well-ventilated kitchen, utility area or passage, a model that meets IS 15558 with a flame failure device and an oxygen depletion sensor, and a service every six months. If your geyser is already inside the bathroom, ask a qualified technician to move or flue it, and until then fill a bucket with the door and ventilator open, then switch the geyser off before you close the door and bathe.

Do I need a carbon monoxide alarm, and where should it go?

If your home burns gas, coal, charcoal, wood or kerosene indoors, an alarm is cheap insurance. The NHS advises fitting one in every room that has a gas, oil, coal or wood-burning appliance. Put one in the room where people sleep too, at head height, and test it regularly. An alarm is a backstop; it does not make it safe to sleep beside a lit angithi.

Can someone recover fully after carbon monoxide poisoning?

Many people do, especially when they are moved to fresh air and given oxygen quickly. But some develop memory, concentration, mood or movement problems days to weeks later, even after seeming to recover. In one large US trial, 46% of patients treated with ordinary oxygen had cognitive problems at six weeks. So anyone who fainted, was confused or was found unconscious should be checked in hospital and followed up, even if they feel fine the next day.