Gas Leaks and Carbon Monoxide Buildup: Causes and Prevention

Natural gas is one of the hallmarks of modern civilization, used for heat and cooking in homes and to fuel power plants. While it is a greenhouse gas and releases CO₂ when burned, it is cleaner and more convenient to transport than coal.

But natural gas can be hazardous. It is flammable and explosive. While not directly toxic to inhale, it can displace oxygen and cause illness through oxygen deprivation. The Centers for Disease Control and Prevention (CDC) examined data about unintentional gas releases between 2010 and 2012 in seven states. In that time, there were 1,369 unintentional gas leaks resulting in 512 injuries and 36 deaths.

Burns were the most common injuries, but inhalation also caused respiratory irritation, dizziness, and headaches. Most leaks are caused by natural gas utilities at pipelines, but some injuries come from in-home leaks.

Standard combustion—of natural gas and other fuels—poses a separate danger: the buildup of carbon monoxide. Carbon monoxide is produced when a fuel is burned with insufficient oxygen (O); complete combustion releases carbon dioxide (two oxygen atoms, CO₂) while incomplete combustion releases carbon monoxide (one oxygen atom, CO).

Carbon monoxide is deadly because it binds to hemoglobin, the protein in blood that carries oxygen, much more efficiently than actual oxygen. High concentrations of CO cause loss of consciousness and death by asphyxiation, and it is especially hazardous because it has no odor or color. According to the CDC, 2,244 unintentional CO deaths occurred between 2010 and 2015.

For your safety, you should understand the common causes of both natural gas leaks and carbon monoxide buildup. By taking the proper precautions, which include using and maintaining equipment properly, being mindful of gas infrastructure, and using carbon monoxide detectors, you and your family can stay safe.

Gas leaks—which include leaks of natural gas and other fuels like propane—occur for two general reasons: damage to gas lines (including utility lines and interior piping) and damage to gas appliances like stoves, grills, furnaces, tanks, and water heaters. In both places, damage can occur from a sudden accident (like cutting an underground gas line),  poor installation, or deterioration arising from poor maintenance.

Natural gas (composed mostly of methane) is colorless and starts out odorless. And you won’t always be able to hear the hiss of a gas leak. For these reasons, the chemical methanethiol, also known as mercaptan, is added to natural gas to make leaks easier to detect. Mercaptan, responsible for the odor of urine after eating asparagus as well as the smell of flatulence, has a sulfuric odor reminiscent of rotten eggs. This pungent smell warns of gas leaks.

Beyond the smell, gas leaks can also be detected in the following ways:

• A hissing or whistling sound caused by gas escaping from a line or appliance
• A dust cloud raised by escaping gas
• Bubbles in water (if a gas line is submerged)

Interestingly (though perhaps less useful to an average homeowner), gas leaking from large utility pipes can harm outdoor plant life by depriving the roots of oxygen. Inexplicably dead or dying plants surrounded by heathy ones might indicate an infrastructure gas leak.

It’s best to prevent gas leaks rather than address them. Because household leaks commonly happen at the gas connection for furnaces and other appliances, the best way to prevent gas leaks is to properly maintain your equipment. By keeping your appliances in good working order, you can avoid the following causes:

• Corroded fittings or connections
• Loose or improperly installed fittings or connections
• Small breaks in gas lines
• A corroded gas shutoff valve

You can routinely check for loose fittings and breaks on your own. But it is wise to have a professional inspect your HVAC system and furnace every year. Moreover, if you ever need to replace a gas coupling, hire a professional. The consequences of getting it wrong are too severe.

Another important part of preventing gas leaks is maintaining ignition sources. Pilot lights are small gas flames that burn regularly in some (especially older) furnaces and stoves so that they can be lit when needed. Many systems use some kind of sensor to automatically stop gas from flowing when the pilot is extinguished, but older ones may not. Know the specifications of your furnaces and stoves and consider upgrading older appliances.

It can be safe to relight extinguished pilot lights while taking necessary safety precautions and explicitly following manufacturer instructions. Ensure that:

• You turn the appliance’s gas valve off before beginning work
• There is no smell of gas before you work
• You have proper ventilation
• The flame remains lit. If the flame is weak or goes out again, turn off the gas and call a professional.

If you have any doubts, call a professional.

Many modern gas-burning appliances use electric igniters instead of pilot lights. These have the advantage of not being able to go out. However, these also can require maintenance. When electric igniters in gas furnaces fail, they may make a repeated clicking noise.

In this case, seek professional help and never attempt to light a furnace manually. Check that gas-burning appliances, including stoves, ovens, and furnaces, ignite properly. If a stovetop burner or oven fails to ignite, turn it off, make sure there are no ignition sources nearby, and ventilate the area before attempting to light it again.

When using a gas grill, take the following precautions:

• Never store a propane tank indoors.
• Inspect propane tanks, lines, and connections for corrosion, rust, and other damage.
• Never fill propane tanks above 80% capacity.
• Check gas grills for leaks after prolonged periods of disuse.
• If your grill fails to ignite, take the same precautions you would with a stove or oven.
• Comply with all local laws. Regulations surrounding the use of gas grills in California, for example, are some of the strictest in the nation.

As mentioned, the most common cause of gas leaks is damage to underground utility lines. If you will be digging on your property, do it safely to avoid breaking gas utility lines (as well as other utilities like fiber-optic cables).

Fortunately, there is a national service to help you know whether it is safe to dig. The number “8-1-1” was established by the Federal Communication Commission (FCC) in 2005 as the universal coordinating number for underground utilities. Calling it connects you to your local utility authority. Remember, call 811 before you dig. Allow several days for a utility service to mark gas, electric, and telecommunication lines. And remember, in some states, it’s required by law:

If you detect (for instance, by smell) a gas leak in your home or elsewhere but do not know the source of the leak, evacuate the building immediately. Leave the door open as you leave and, exercising common sense, open windows and other doors and extinguish any flames if it is safe to do so. Do not cause a spark by using lighters or operating light switches or other electronics while inside. Call 911, but do so away from the building.

As explained by Pacific Gas and Electric (PG&E), turning off the gas at the gas meter can be a useful step in the event of a leak if you know how and it is safe to do so. Learn where your gas meter and its shut-off valve are located. Only turn off the gas at the meter in an emergency. A technician is required to turn it back on. Turning off the gas at the meter probably requires a wrench.

This video explains how to shut off a home gas line in an emergency (and mentions that most fatalities in earthquakes stem from gas leaks caused by the quakes):

Unlike natural gas and propane, carbon monoxide (or CO) isn’t useful. It is merely an accidental byproduct of combustion. When combustion (such as in a gas furnace or oven) is incomplete, CO is produced. Car exhaust also contains high concentrations of CO. 

As the gas binds with hemoglobin in the blood and prevents oxygen from binding, it causes symptoms described by the CDC as “flu-like,” such as dizziness, headache, weakness, upset stomach, vomiting, chest pain, and confusion. Prolonged exposure causes loss of consciousness and eventually death by asphyxiation and, again: CO has no odor and no color.

Fortunately, there are steps you can take to stay safe. You can minimize your risk by properly using and maintaining your gas-burning appliances. And you can use a carbon monoxide detector to provide warning of a problem.

When fuel-burning equipment is not properly taken care of or used improperly in an enclosed space, CO can build up. To avoid CO poisoning, there are several things you must not do:

• Never use stoves or ovens to heat your home.
• Never patch or cover vents. Proper ventilation is important for complete combustion and the escape of CO.
• Never burn charcoal indoors.
• Never use portable camp stoves or gas-burning lanterns indoors. This includes use in garages, carports, tents, or trailers.
• Never use a generator indoors or near a window or door. Again, “indoors” includes garages, carports, tents, and trailers.
• Never run a car engine in a garage or other enclosed space, even if the garage door is open. This is incredibly dangerous. Take care, especially, with push-button and remote-start cars; forgetting to turn off the car can be lethal.

The single most important step you can take to protect yourself from CO poisoning is to install CO detectors in your home. CO detectors, similar to smoke detectors, give a loud alert when levels of the gas become elevated.

Frontpoint’s Carbon Monoxide Sensor goes beyond a loud alarm and immediately summons help via a professional monitoring service. This quick call for assistance can be a lifesaver, since the gas may quickly incapacitate people without them even knowing there is a buildup of it.

When your CO sensor sounds, evacuate to fresh air and call 911 (help may already be on the way, with a monitored security system).

Check out our article on the importance of having an escape plan for emergencies like fires and carbon monoxide buildup.  

The number of CO detectors you need will vary, but a good place to start is:

• One detector on each floor
• One detector in or immediately outside of each bedroom
• One detector in the basement

Beyond keeping CO detectors in your home, you can prevent CO buildup by properly maintaining your equipment and allowing for proper ventilation. Don’t crowd vents or appliances with objects!

Both natural gas leaks and CO buildup can be deadly. But they are usually avoidable hazards. By properly using and maintaining fuel-burning appliances, you can prevent them from leaking gas into your home or causing CO to build up. A Carbon Monoxide Sensor is also an essential precaution, enabling you to escape quickly and summoning help right away in the event of an emergency.

Also, make sure you are protected from fire. A Smoke and Heat Sensor is just as indispensable as a CO sensor and monitored security systems ensure that the fire department is dispatched—whether you are home or not.

Frontpoint keeps homes safe whether families are there or not. We've been revolutionizing the home security industry for over a decade. And we're just getting started. To shop DIY home security systems, check out our Security Packages. If you have questions or would like to discuss a quote, contact us at 1-877-602-5276.