The single most important rule for preventing carbon monoxide poisoning from a generator is to never run it indoors or in any enclosed space, and to place it at least 20 feet from your home’s doors, windows, and vents. Between 2012 and 2022, generators caused nearly 800 carbon monoxide deaths in the United States, with 77% of those occurring at residential locations. Almost every one of those deaths was preventable.
Why Generator Exhaust Is So Dangerous
Generators burn gasoline or propane, and like any combustion engine, they produce carbon monoxide (CO) as a byproduct. CO is colorless and odorless, so you can’t detect it without an alarm. What makes it lethal is how it behaves in your bloodstream: CO binds to hemoglobin with 200 times the affinity of oxygen. Once it latches on, it displaces oxygen and chokes off delivery to your tissues. It also directly shuts down the energy-producing machinery inside your cells.
Your brain and heart burn through the most oxygen of any organs, so they fail first. As your heart tries to compensate by pumping harder, it eventually can’t keep up, which starves both itself and the brain even further. This creates a cascading cycle that can lead to unconsciousness and death surprisingly fast. People who are asleep, intoxicated, or otherwise impaired can die before ever noticing a symptom.
Place the Generator at Least 20 Feet Away
Position your generator outdoors, at least 20 feet from any door, window, or vent on your home. Point the exhaust away from the house, not toward it. Even at 20 feet, CO can drift back inside through an open window or a dryer vent if the exhaust is aimed in the wrong direction.
Garages, carports, basements, crawlspaces, sheds, and breezeways are all off-limits, even with the door wide open. Deadly concentrations of CO build up within minutes in these spaces, and the gas can linger for hours after the generator is turned off. Fans and open doors do not move enough air to keep levels safe. The Consumer Product Safety Commission is explicit on this point: no enclosed or semi-enclosed space, no exceptions.
Install Battery-Powered CO Alarms
Place battery-powered or battery-backup CO alarms on every level of your home and near sleeping areas. During a power outage, hardwired alarms without battery backup go silent, which is exactly when you’re most likely to be running a generator.
Current CO alarms certified under UL 2034 standards are designed to detect concentrations at 30 parts per million and above. Test your alarms monthly and replace the batteries at least once a year. Most CO alarm units should be replaced entirely every five to seven years (check the manufacturer’s label for the specific expiration date). If the alarm sounds while you’re running a generator, get everyone out of the house immediately and move to fresh air before doing anything else.
Recognize CO Poisoning Symptoms Early
The earliest symptoms of carbon monoxide exposure are a headache, dizziness, and weakness. As exposure continues, you may develop nausea, vomiting, chest pain, and confusion. These are often mistaken for the flu, especially during winter storms when generators see the heaviest use. The key difference: CO poisoning doesn’t cause a fever, and symptoms improve quickly once you move to fresh air.
Confusion is the symptom that makes CO especially treacherous. By the time your thinking becomes impaired, you may not be able to recognize what’s happening or make the decision to leave. If anyone in your household develops a sudden headache or dizziness while a generator is running, treat it as a CO emergency until proven otherwise.
Look for Generators With CO Shutoff Technology
Newer portable generators come equipped with built-in CO sensors that automatically shut the engine off when carbon monoxide concentrations get too high. Two voluntary industry standards govern these systems. The stricter of the two, UL 2201, requires the generator to shut down when CO levels near the unit reach 400 parts per million instantly or average 150 parts per million over a rolling 10-minute window. The other standard, PGMA G300, uses higher thresholds of 800 ppm instantaneous and 400 ppm over 10 minutes.
The Consumer Product Safety Commission has proposed a federal safety standard that would align with the stricter UL 2201 thresholds and also cap CO emissions at 150 grams per hour. If you’re buying a new generator, look for one that meets UL 2201 or advertises an automatic CO shutoff feature. This technology is a meaningful safety net, but it’s a backup, not a substitute for proper outdoor placement. A generator with CO shutoff that’s running inside a garage can still produce dangerous levels before the sensor triggers.
Protect the Generator From Weather Safely
Power outages often happen during storms, which creates a dilemma: the generator needs to stay dry, but it also needs to stay outside. The solution is a canopy-style cover or a purpose-built weatherproof enclosure designed specifically for generators. These enclosures feature vents or louvers that allow airflow for both the engine’s air intake and exhaust while keeping rain out. A simple pop-up canopy with open sides also works in a pinch.
What you should never do is bring the generator into a garage or covered porch to keep it dry. Water damage to a generator is repairable. Carbon monoxide poisoning is not always reversible.
Keep Up With Basic Maintenance
A poorly maintained engine produces more carbon monoxide than a well-tuned one. Before storm season, inspect your generator for damage, check for loose or cracked fuel lines, and make sure the air filter is clean. Run the generator periodically throughout the year so fuel doesn’t go stale in the carburetor, which leads to incomplete combustion and higher CO output. Follow the manufacturer’s maintenance schedule for oil changes and spark plug replacement.
Store fuel in approved containers away from the generator and away from your home. Never refuel a generator while it’s running or still hot. Spilled gasoline on a hot engine is a fire hazard, and a fire in a confined space compounds the CO risk dramatically.
Power Outage Checklist
- Before the outage: Confirm your CO alarms have fresh batteries and are not expired. Identify an outdoor spot at least 20 feet from any opening in your home.
- When setting up: Place the generator on a flat, dry surface outdoors. Aim the exhaust away from the house. Use heavy-duty outdoor-rated extension cords to bring power inside rather than running the generator closer.
- While running: Never open a window or door “just a crack” near the generator to run a cord through. Check on the generator periodically but avoid lingering near the exhaust.
- If your CO alarm sounds: Leave the house immediately. Call 911 from outside. Do not go back in to turn off the generator until the space has been cleared by emergency responders.
The 37 generator-related CO deaths reported in 2022 alone (with that number likely to rise as delayed reports come in) represent a persistent, preventable problem. Every one of these precautions is simple, and together they reduce the risk to nearly zero.