Leave immediately, avoid anything that could create a spark, call 911 or your gas supplier from well away from the house, and do not return until emergency responders or a qualified professional says it is safe. Treat any smell of rotten eggs or sulfur as a possible natural-gas or propane leak—even if the odor is faint, intermittent, or you cannot identify its source.
What to do right now
- Get everyone out. Tell all occupants to leave the house or affected area immediately. Take pets if they can be removed without delaying your exit. Do not stay inside to investigate, find the leak, or collect belongings.
- Do not create a flame or spark. Do not light a match, smoke, vape, burn a candle, or operate a flashlight. Do not switch lights or appliances on or off, use electrical outlets, start a vehicle, or operate any other electrical equipment while leaving.
- Do not use a phone inside or near the odor. Once you are safely away from the suspected leak, use a mobile phone or another phone to call for help.
- Call from outside and report the suspected leak. Call 911 or your local natural-gas utility. If the home uses propane, call the propane retailer or supplier. If the supplier cannot be reached—or there is immediate danger—call 911 or the fire department. Report the odor even if you think a neighbor, another occupant, or someone else may already have called.
- Keep away. Move people and pets away from the building and wait at a safe location. Do not go back inside until the utility, fire department, emergency responders, propane supplier, or another qualified professional has determined that it is safe.
If the smell is strong, someone hears hissing or blowing, or anyone feels ill, treat the situation as an emergency and call 911 from a safe location. Do not try to confirm the leak with a lighter, match, candle, electronic device, or vehicle.
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Why a gas smell must be treated seriously
Natural gas itself is naturally odorless. Utilities add odorants such as mercaptan so that a leak is easier to notice; the resulting smell is commonly compared with rotten eggs or sulfur. A smell is not the only possible warning sign. Other signs can include a hissing or blowing sound, unexplained increases in gas use, bubbling water, blowing dirt, or dead and discolored vegetation near an outdoor gas line.
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- Easy Installation - simply plug-in to a standard, 120V outlet in your home
- 9-volt battery backup provides protection during a power outage
- Digital LED display shows the level of carbon monoxide the CO alarm is sensing or states "GAS" when explosive gas is present
- 85-decibel alarm announces when carbon monoxide or explosive gas is detected
- Peak Level Memory records the last time carbon monoxide was detected or when the unit was last tested
Natural gas and propane: the response is similar, but the equipment differs
| Fuel | Who to call | Important valve guidance |
|---|---|---|
| Utility-supplied natural gas | 911 or the local natural-gas utility | Do not assume you should shut off the meter valve yourself. Leave and follow instructions from the utility or emergency responders. If the valve has been shut off, do not turn it back on; qualified utility personnel should handle restoration. |
| Propane | Your propane retailer or supplier; call 911 or the fire department if the supplier cannot be reached or danger is immediate | Propane guidance may permit shutting the tank valve only when it is safe, the suspected leak is not at the tank, and you know how to do it. This must never delay evacuation, and you should not attempt it if you are uncertain. |
For either fuel, do not repair a pipe, connector, regulator, tank, appliance, or gas control yourself during the emergency. The fuel type changes whom you contact and may affect valve instructions; it does not change the basic rule: get out, avoid ignition sources, call from outside, and wait for clearance.
If you smell gas outdoors
Move away from the odor and call 911 or the natural-gas utility from a safe location. Keep clear of meter boxes, excavations, manholes, drains, and other low areas where gas may collect. Do not start a vehicle or create a flame or spark near the suspected leak. Keep other people away until responders arrive.
Do not confuse a gas leak with carbon monoxide
Carbon monoxide (CO) is a different hazard. CO is colorless and odorless, so you cannot use your sense of smell to detect it. Fuel-burning furnaces, ranges, water heaters, fireplaces, generators, grills, and other equipment can produce CO when they malfunction or are used incorrectly.
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Possible CO-poisoning symptoms include headache, dizziness, weakness, upset stomach, nausea, vomiting, chest pain, shortness of breath, confusion, altered mental status, and loss of consciousness. If a CO alarm sounds or anyone has possible CO symptoms:
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- Move everyone to fresh air immediately.
- Call 911 from outside.
- Do not re-enter until authorities or qualified professionals say it is safe.
Do not wait for a gas odor before responding to a suspected CO problem. A natural-gas detector does not replace a CO alarm, and a CO alarm does not normally detect a natural-gas leak.
What detectors can—and cannot—do
A natural gas detector can be a useful supplemental warning device after the immediate danger has been addressed. It is not a reason to remain inside, search for the source, or wait for an alarm when you already smell gas. If you smell gas, evacuate and call from outside regardless of whether a detector sounds.
Homes with fuel-burning appliances, an attached garage, or other CO risks should have CO alarms on every level and outside sleeping areas. Install, test, replace, and maintain alarms according to the manufacturer’s instructions. A CO alarm is an additional layer of protection against odorless combustion gas; it does not detect a typical natural-gas or propane leak.
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What not to do
- Do not remain inside to open windows or doors. Ventilation is not worth delaying evacuation or operating a switch, appliance, or other device.
- Do not look for the leak with a flame. Never use a lighter, match, candle, or other ignition source.
- Do not operate electrical equipment. This includes lights, switches, appliances, outlets, flashlights, phones, and vehicles while you are in or near the suspected leak.
- Do not assume the danger is over because the smell disappears. Odor can dissipate; professional clearance is still required.
- Do not repair or relight anything yourself during the emergency. Do not restore gas service or relight appliances unless the responsible utility gives specific, situation-appropriate instructions or a qualified professional handles it.
- Do not use a gas oven or range as a heater. Never use generators, grills, camp stoves, or similar fuel-burning equipment indoors or near doors, windows, or vents because of the risk of carbon monoxide.
What happens before you can use the house again
Wait for the utility, fire department, emergency responders, propane supplier, or another qualified professional to determine that the building is safe. A disappearing odor is not clearance.
Before using the system again:
- Have the gas system and affected appliances inspected.
- Repair the source of the leak through qualified professionals.
- Have appliances properly checked and relit or restored by the responsible utility or a qualified technician.
- Replace gas controls, wiring, breakers, fuses, or appliances that were damaged or flooded, as directed by qualified professionals.
- Follow any utility or fire-department instructions about entry, ventilation, shutoff, repair, and restoration.
If the incident requires post-emergency work, arrange a qualified gas-system inspection through an appropriately licensed gas-appliance, HVAC, plumbing, or gas-line professional. Licensing and service availability vary by location, so confirm that the contractor is qualified for the type of fuel and work involved. For propane homes, the propane supplier may be the appropriate first contact for system checks and tank-related guidance.
Preventing future gas and CO emergencies
- Install and maintain CO alarms on every level and outside sleeping areas, following the manufacturer’s instructions.
- Consider a natural-gas detector as a supplemental early-warning device, but never treat it as a substitute for evacuation and emergency reporting.
- Have fuel-burning appliances, venting, connectors, and gas equipment inspected and serviced by qualified professionals.
- Never operate generators, grills, camp stoves, or other fuel-burning equipment inside a home, garage, or enclosed area, or near doors, windows, or vents.
- Before digging on the property, contact 811 so underground utility lines can be located and marked.
- Make sure household members know the outdoor meeting place and understand that calls must be made from away from the suspected leak.
A simple decision guide
| Situation | Action |
|---|---|
| You smell rotten eggs or sulfur inside | Leave immediately, avoid flames and electrical equipment, call 911 or the gas utility from outside, and stay out until cleared. |
| You smell gas outside | Move away from the area, avoid low areas and ignition sources, and call 911 or the gas utility from a safe location. |
| You smell propane | Evacuate first, then call the propane supplier. Call 911 if danger is immediate or the supplier cannot be reached. |
| A CO alarm sounds or someone has CO symptoms | Move to fresh air, call 911, and do not re-enter until authorities or qualified professionals approve it. |
| The smell has stopped | Do not assume the home is safe. Stay out and wait for professional assessment. |
Frequently Asked Questions
Should I open the windows if my house smells like gas?
No—not if doing so delays evacuation or requires operating a switch, appliance, phone, or other device. Leave immediately and call 911 or the gas supplier from a safe location. Responders or qualified professionals can determine how the building should be handled.
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- Easy installation, no wiring needed, detects during a power failure by operating on 2-AA batteries (included); Install on a wall of your home or place on a tabletop
- Green LED indicates power to the carbon monoxide detector, while an 85-decibel alarm & a red LED indicates the presence of carbon monoxide
- Event Memory records the last time carbon monoxide was detected or when the unit was last tested
Can I shut off the gas meter myself?
For utility-supplied natural gas, do not assume that shutting off the meter is necessary or safe for an untrained occupant; leave and follow the utility’s or emergency responders’ instructions. Propane guidance may allow closing the tank valve only when it is safe, the suspected leak is not at the tank, and you know how to do it. Never delay evacuation, and never turn a shutoff valve back on yourself.
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There is no safe homeowner-set waiting period. Stay out until the gas utility, fire department, emergency responders, propane supplier, or another qualified professional has inspected the situation and says re-entry is safe.
Will a carbon monoxide detector detect a natural-gas leak?
No. Carbon monoxide is a separate, odorless combustion hazard. CO alarms are important near sleeping areas and on every level, but they do not normally detect an ordinary natural-gas or propane leak. A natural-gas detector is also only a supplemental warning device and does not change the required response to a gas odor.
The Bottom Line
Gas smell means get out first. Avoid flames, switches, appliances, phones, and vehicles until you are away; call 911 or the appropriate gas supplier from outside; keep everyone away; and wait for professional clearance before re-entering or restoring service.
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