Respond to a Carbon Monoxide Alarm in a Ventless Basement Rental

Summary

Safety first

• Never silence the alarm without investigating.
• Do not attempt to ventilate a ventless basement or stop the source yourself.
• Stop and leave immediately if you feel dizzy, nauseous, or lightheaded.
• Never re-enter the apartment until emergency responders clear it as safe.
• Avoid delays due to weather, pets, or gathering personal items.

Tools you’ll need

• Cell phone
• Spare keys
• Shoes and coat (if cold outside)
• Flashlight (optional)

Materials

• Carbon monoxide alarm (already installed)
• Emergency contact information

Step-by-step

• Do not ignore the alarm—treat every activation as a real emergency.
• Without delay, gather your phone, keys, and any pets.
• Leave the basement apartment immediately—don’t attempt to locate the CO source.
• If route blocked, leave through the quickest exit (use building’s main doors if no basement exit).
• Call 911 once safe outside and inform them of your location, the alarm, and recent heating maintenance.
• Wait for first responders to assess the situation; do not re-enter the apartment until cleared.
• Contact your landlord to notify them of the situation after speaking to emergency personnel.

Troubleshooting

• If the alarm won’t stop after leaving, don’t try to reset—let responders handle it.
• If you can’t exit through the main apartment door, try any accessible emergency exits.
• If you feel symptoms before you can exit, crawl low to the ground toward the exit.
• Call 911 for guidance if you’re trapped or unsure how to evacuate.

Common mistakes

• Assuming the alarm is false, especially after maintenance.
• Staying inside to find the cause or ventilate in a windowless basement.
• Forgetting to bring essentials (keys, phone) while evacuating.
• Not notifying emergency services or waiting for confirmation that it’s safe to return.
• Ignoring mild symptoms of CO poisoning.

When to call a pro

• Call 911 immediately if the alarm sounds—never try to diagnose or fix CO issues yourself.
• If your alarm sounds repeatedly after repairs, ask your landlord to have heating and alarm systems professionally checked.
• Contact emergency services right away if anyone experiences any symptoms.

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