What to do if you smell gas or your carbon-monoxide alarm sounds

Short answer: Treat the smell of natural gas and a sounding carbon-monoxide alarm as life-safety emergencies. Smell of gas → get everyone out without using switches, phones, or garage-door openers; call Enbridge Gas 24/7 emergency: 1-866-763-5427 from outside; do not re-enter until the utility clears the home. CO alarm sounds → get everyone (and pets) into fresh air immediately; call 911 or the fire service; do not re-enter until first responders declare the space safe. Only after the home has been declared safe do you call a licensed HVAC technician to find and fix the source.

Why this matters in Ontario

Natural gas is odourless in its native state, the "rotten egg" or sulphur smell you notice is a chemical called mercaptan that Enbridge deliberately adds so leaks are detectable. Carbon monoxide (CO) is worse: it's completely odourless, colourless, and tasteless. In Ontario, homes with a fuel-burning appliance or an attached garage are required by law to have a working CO alarm on every storey where people sleep. When either warning fires, the correct response is the same across the GTA: get out first, call the authority second, call a technician third.

If you smell natural gas

Follow the sequence Enbridge Gas publishes on their public safety page:

1. Do not use anything electrical. No light switches, no thermostats, no garage-door openers, no phones inside the house. A single spark can ignite an accumulation of natural gas.
2. Do not smoke, do not use a lighter, do not start a vehicle in an attached garage. Extinguish any open flame — fireplace, gas stove, candle — only if you can do so without a spark.
3. Get everyone out. Move all people and pets outside, away from the building. If it's safe on the way out and you can do so without delaying anyone, open a window or exterior door.
4. Do not use your phone inside the home. Once you are outside and clear of the property, call Enbridge Gas's 24-hour emergency line: 1-866-763-5427. In a life-threatening emergency, call 911 first.
5. Do not go back inside — for any reason — until Enbridge or first responders declare the home safe.

Enbridge dispatches technicians 24/7 for suspected leaks at no cost to the homeowner. Their responder will locate the source (usually a fitting, valve, appliance connector, or the meter itself), isolate it, and if necessary lock the meter until the appliance is repaired.

If your carbon-monoxide alarm sounds

Carbon monoxide is a byproduct of incomplete combustion, most often from a cracked heat exchanger in an aging furnace, a blocked vent, an unmaintained fireplace or water heater, or a running vehicle in an attached garage. Enbridge's CO safety guidance lines up with the Ontario Fire Marshal's response protocol:

1. Get everyone (including pets) into fresh air immediately. Symptoms of CO exposure — headache, nausea, dizziness, confusion, drowsiness — can look like the flu but progress rapidly.
2. Call 911 or your local fire service from outside. Do not delay to gather belongings or open windows.
3. Do not re-enter the home until first responders (fire service and/or Enbridge) have measured CO levels, ventilated the space, and declared it safe.
4. Seek medical attention if anyone has symptoms, even mild ones. CO binds to haemoglobin, so recovery requires oxygen therapy, and delayed effects can appear hours later.
5. Do not silence the alarm or remove its batteries to "make it stop." A sounding alarm is doing the job you bought it for.

Once the home is declared safe, the fire service or Enbridge will typically recommend not restarting the suspected source appliance until a licensed HVAC technician has inspected it and cleared the fault.

The common misconception: "I'll open the windows and see if it clears"

The instinct to ventilate a home and see whether the smell or alarm resolves is understandable, and dangerous. A gas leak large enough to smell is large enough to reach an ignition source before the ventilation catches up. A CO alarm sounding means CO has already accumulated to a level that can cause harm; opening a window and staying inside exposes you to that level for however long it takes to clear. In both cases, the correct order is get out first, then let the professionals decide when it is safe to go back in.

After the home has been declared safe — this is when you call us

Once Enbridge or first responders have cleared the space, the next step is finding and correcting the source. A licensed technician will:

• Pressure-test the gas piping to find and correct any leak.
• Inspect every fuel-burning appliance in the home — furnace heat exchanger, water heater burner, fireplace, boiler — with a combustion analyzer and manometer.
• Verify vent draft and confirm combustion gases are exiting the home correctly.
• If a defect is found that cannot be immediately corrected, apply a red tag and lock the appliance out.
• File all TSSA and utility paperwork on your behalf.

Energy Clean provides 24-hour emergency dispatch across the GTA for post-alarm inspection, red-tag correction, and heat-exchanger diagnostics. If your CO alarm has sounded, book us as soon as the home has been declared safe by the fire service or Enbridge. Priority scheduling applies.

Prevention: the four things that would have caught this earlier

1. Working CO alarms on every storey where people sleep: this is Ontario law under the Hawkins-Gignac Act (2013). Batteries replaced every year, whole alarm replaced every 7 years.
2. Annual furnace and water-heater maintenance. A combustion analyzer catches a heat-exchanger crack, a partially blocked vent, or a marginal draft before it becomes an emergency. See our Home Comfort Plans for automatic annual scheduling.
3. Never run a vehicle, generator, or gas-powered tool in an attached garage: even with the garage door open, CO accumulates rapidly.
4. Know your emergency numbers before you need them. Enbridge Gas 24/7 emergency: 1-866-763-5427. Life-threatening emergency: 911. Post-emergency HVAC dispatch: your regular Energy Clean line.

For additional homeowner guidance on winter fuel-appliance safety, see Enbridge Gas Safety, the full authoritative reference for gas safety in our service area.