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8 Common Gas Leak Symptoms You Need to Know Now

Gas leaks can kill.

Whether new to a property or decades into a tenancy, learning how to spot the signs of a gas leak is extremely important in ensuring the safety of the inhabitants of the home. 

Get to know boiler gas leak symptoms like the back of your hand, like how to identify the unmistakable gas leak smell, what to do with a gas leak, and find out how to detox from natural gas poisoning now.

8 Gas Leak Symptoms and Signs of a Gas Leak – How To Tell If You Have a Gas Leak Now

There are several telling signs of a gas leak, most of which are quite obvious to spot. Get to know the most common gas leak symptoms below.

1. Foul Smell 

Gas actually has no odor; gas companies are obligated to odorize it with Mercaptan, a harmless chemical, as a warning sign.

2. Hissing Sound

Auditory signs are obvious as well.If a gas pipe is broken, you’ll likely notice a whistling sound, like that of a boiling kettle, or a quiet hissing sound near a gas line. 

3. Bubbled Water and Dust Clouds

Visual signs to look out for include bubbled water outside the home, dusty clouds near gas lines, and physical damage sustained to the gas pipe. These are signs that gas is leaking, and maybe entering the soil.

4. Headaches 

The most common physical symptom of both short and long term natural gas exposure is headaches. Notice if multiple people in the house are experiencing them. Headaches and fatigue are not signs of natural gas poisoning per se, but may be caused by exposure to low levels in the air.

5. Asthma

People with existing breathing problems, like asthma, will experience an obvious flare up if exposed to natural gas, since it alters the composition of air and reduces the amount of oxygen in the lungs.

6. Nausea & Nosebleeds

More severe gas leak symptoms include nausea and vomiting, nosebleeds, and fainting. These may also be ‘slow gas leak symptoms’, issues caused over time by prolonged exposure to natural gas, and may indicate natural gas poisoning. 

7. Abnormal Behaviors & Reactions in Pets

Natural gas poisoning symptoms in dogs and cats are much the same as in humans, but since their bodies are so much smaller, they are likely to exhibit more severe symptoms much faster. Keep an eye on them for excessive fatigue, vomiting, and passing out.

8. Dead Plants

Extremely low levels of natural gas in the air may not cause obvious symptoms in pets or humans, but it will in plants. If previously healthy house plants suddenly wilt and die, it may indicate a change in the composition of the air.

How do you check if the gas is leaking?

1. After identifying the smell, listen out for hissing. The sound of gas escaping will likely make a whistling sound.
2. Cautiously approach the area where the hissing is loudest, making sure that all doors and windows are wide open if it is inside the home to increase oxygen in the air.
3. Add a small amount of washing-up liquid or hand soap to some water, and apply it to suspect areas where the sound is loudest.
4. If bubbles are produced, there is likely gas leaking. Shut the gas supply off.
5. Call the gas company immediately and follow their instructions. Do not attempt to deal with the leak.

4 Types of Gas Leaks

Though the symptoms and signs are similar, it’s important to have an idea of the different types of gas leaks that can occur in the home.

1. Natural Gas Leak

‘Natural gas’ is methane. It’s formed over thousands of years and is extracted in every continent in the world, making it one of the most prominent causes of climate change. 

Gas works in Seattle, Washington

Natural gas is highly combustible, meaning an explosion or fire could occur should something ignite it. The danger this poses is far more worse than exposure to natural gas.

2. Liquid Petroleum Gas (LPG)

LPG refers to other hydrocarbon gasses stored as liquids. This is mostly propane, which may be mixed with butane or propylene. 

Person heats a pan for cooking using a propane canister

LPG is freezing cold, so approaching it could easily cause cold burns. It is also highly flammable, so electrical switches and sources of ignition should not be touched under any circumstances. 

Like natural gas, mercaptan is added to create a universally recognizable smell.

3. Carbon Monoxide

The presence of carbon monoxide is caused when gas (or coal or wood) doesn’t burn properly. It will emit from gas appliances, like cookers, heaters, and boilers, that don’t burn properly due to poor maintenance, fitting, or construction. 

Unlike methane and propane, carbon monoxide is odorless and colorless, making it much harder to detect. That makes it much more dangerous.

Symptoms of being poisoned are like those caused by exposure to other types of gas leak, but they are likely to be much more severe. 

Burning coals

Aside from that, keep an eye on appliances. Floppy stove flames or pilot lights that burn yellow/orange rather than blue suggest the presence of carbon monoxide. 

Staining, soot, and smoke may also indicate the presence of carbon monoxide.

4. Freon/Liquid Coolants

Fridges and AC units use chemical coolants known by the brand name ‘Freon’. Freon provides the cool air by undergoing a constant process of evaporation.

An AC gas leak or a fridge gas leak will be much more obvious than other types of gas leaks, because there’s a high chance that there will be considerable structural damage to the product itself, like a puncture.

White air conditioner

Even if structural damage isn’t obvious, the fridge or AC will fail to work as it should. The AC may produce hot air, for instance, or make a buzzing sound, while the fridge may defrost and fail to keep food adequately cool.

The 4 Essential Gas Leak Prevention Tips To Know

Preventing a gas leak is not the most straightforward of tasks, but there are certain precautions that must be taken in homes and other interior spaces.

1. CO alarms

Carbon monoxide alarms remain the only reliable way to spot a CO gas leak. Every home must have at least one carbon monoxide alarm, prioritizing spaces near boilers, gas cookers, and other gas-powered devices, like space heaters.

2. Battery checking

Alarms will be powered by battery, so it’s important to get into the habit of checking its power every month. Likewise, fire alarms should also be checked regularly.

3. Regular maintenance

All reputable energy providers should provide 24-hour maintenance and emergency service. Call the provider if it hasn’t been serviced in some time to arrange for a professional to assess it. 

Similarly, products that use liquid coolants, like air conditioners and fridges, should be assessed. Building habits is wise when it comes to taking preventative measures.

4. Ventilation

In a general sense, ensuring the home has good ventilation will help prevent poisoning, so make sure to keep ventilation shafts and cooker fans clean and in working order. 

If burning a fire inside, make sure the chimney has regular cleaning and maintenance. Barbecuing, or any form of cooking that uses propane or coal, should be done in large open spaces.


Does carbon monoxide smell like nail polish?

Carbon monoxide does not smell like nail polish because it is odorless. The only way to reliably detect it is through a carbon monoxide detector. Coolants like Freon, however, do smell similar to nail polish or chlorine.

How to tell if there is a gas leak?

Natural gas is scented with a chemical agent, so that it smells like rotten eggs. A hissing sound may also be produced depending on the nature of the leak. For carbon monoxide leaks, a CO alarm will sound.

Will a carbon monoxide detector detect a gas leak?

A carbon monoxide detector sounds when it detects dangerous levels of CO in the air. There is a high chance that there is a gas leak somewhere, but it doesn’t suggest anything conclusive about the source. Carbon monoxide is created when gas burns improperly.

What does gas smell like?

Natural gas and liquid petroleum gas (propane, butane, etc.) smell sulfuric, like rotten eggs or cabbage.Coolants like Freon are also pungent, with a scent like nail polish or chlorine.

Can inhaling gas make you sick?

Yes. As the composition of the air changes, less oxygen will be in your blood. At a certain point, this could asphyxiate you and cause death. Symptoms to look out for include headaches, dizziness, and nausea. More severe symptoms include passing out, breathing problems, and nosebleeds.

Can a gas leak make you ill?

Yes, gas leaks can make you ill. As the composition of the air changes, less oxygen will reach the blood. At a certain point, this can asphyxiate and cause death. Symptoms to look out for include headaches, dizziness, and nausea. More severe symptoms include passing out, breathing problems, and nosebleeds. Carbon monoxide is more dangerous than natural gas, because it is poisonous to humans. 


Knowing gas leak symptoms and signs to look out for can mean the difference between life and death, and it’s important that suspicions are always taken seriously.

Making a habit of preventative measures, like regular maintenance, assessments, and checking alarms for power, will help avoid being ill-prepared for gas leaks.