Why “cracking a garage door” still isn’t safe for generators, and what CPSC keeps warning about

Every time a major storm knocks out power, the same dangerous myth resurfaces: that you can safely run a generator in the garage if you “just crack the door.” You cannot. The physics of carbon monoxide, and the way homes are built, turn that shortcut into a trap that can quietly kill you and your family in minutes. Understanding why the U.S. Consumer Product Safety Commission keeps repeating the same blunt warning is as essential to your emergency plan as flashlights and bottled water.

To use a generator without gambling on carbon monoxide poisoning, you need more than a rule of thumb. You need to know how the gas behaves, how quickly it builds up, and why even partial ventilation is nowhere near enough. You also need to understand what regulators, safety agencies, and manufacturers are changing, and what still depends entirely on your choices when the lights go out.

Why “a little ventilation” is a deadly illusion

The core problem with running a generator in a garage, even with the door partially open, is that carbon monoxide does not politely drift outside. It mixes with the air in the space, seeps through every crack into your home, and can reach lethal levels long before you smell or see anything wrong. In its own Carbon Monoxide Hazards alert, the Consumer Product Safety Commission explains that when you use a portable generator in a confined space, it can produce high levels of CO within minutes, not hours, which means your margin for error is essentially zero.

Garages, basements, and enclosed porches all behave like partial boxes, not open fields. Even if you think you have “enough airflow,” the exhaust from a small engine is concentrated and hot, so it rises, hits the ceiling, and spreads sideways, where it can be pulled into your living space by your furnace, bathroom fans, or even the natural stack effect of warm air rising through the house. That is why federal guidance stresses that you should NEVER operate a portable generator inside a home, garage, basement, crawlspace, shed, or other enclosed area, and why the CPSC repeats that warning in winter storm advisories that urge you to treat any enclosed or attached structure as off limits for generator use.

What CPSC actually says about garages and generators

If you read the fine print of federal safety messaging, there is no wiggle room about garages. In multiple seasonal alerts, the CPSC tells you to NEVER operate a portable generator inside a home, garage, basement, crawlspace, shed, or similar structure, because even short-term use can create a buildup of lethal levels of CO. One winter advisory aimed at families facing outages during severe weather spells out that in the case of a power outage you must follow life saving tips that start with keeping generators out of any enclosed or attached space, including the garage, to prevent the rapid accumulation of carbon monoxide that can render you unconscious before you realize there is a problem.

The same uncompromising language appears in hurricane season guidance that frames generator use under the heading of Loss of Power and emphasizes Using a Generator Safely. There, the CPSC again states that you should NEVER run a generator in a home, garage, basement, crawlspace, shed, or similar area, and that the machine must be kept outside, away from windows and doors, so exhaust cannot drift back inside. A later winter storm bulletin repeats that Dec guidance, again telling you to NEVER operate a portable generator inside a home, garage, or other enclosed space, underscoring that the rule is not situational or seasonal. If the generator is in a garage, even with the door open, you are using it in a way the CPSC explicitly warns against.

How carbon monoxide behaves inside your home

To understand why cracking the garage door does not work, you need to understand what carbon monoxide is and how it moves. The CPSC’s Protect Your Family materials describe carbon monoxide, also known as CO, as a colorless, odorless gas that can cause Carbon Monoxide Poisoning without any sensory warning, which is why people often succumb while they are asleep or feeling only mildly ill. Once CO enters your bloodstream, it binds to hemoglobin more strongly than oxygen does, starving your organs of the oxygen they need and leading to confusion, loss of consciousness, and death if exposure continues.

Because CO is roughly the same density as air, it does not simply “sink” or “rise” out of your way. It mixes evenly into the air in whatever space it enters, and then follows the airflow patterns of your home. That means exhaust from a generator in the garage can be pulled through tiny gaps around the door, through shared ductwork, or via vents and chases that connect the garage to the rest of the house. Once inside, it can accumulate in bedrooms and living areas, especially if windows are closed against cold or storm conditions. That is why the CPSC’s Carbon Monoxide Information Center tells you to Never use portable generators inside homes or garages, even if doors and windows are open, and to get outside immediately and then call 911 if your CO alarm sounds.

Why storms make the “garage myth” especially dangerous

Power outages rarely happen on calm, pleasant days. They arrive with winter storms, hurricanes, and tropical systems that push you to improvise. When temperatures plunge or winds howl, it is tempting to tuck a generator into the garage or under a carport to shield it from snow and rain. Federal safety officials know that pattern well, which is why their storm advisories keep repeating the same blunt message: in the case of a power outage, NEVER operate a portable generator inside a home, garage, or other enclosed space, because the risk of lethal levels of CO is highest when you are already stressed, tired, and more likely to overlook early symptoms of poisoning.

Hurricane season guidance makes the same point from a different angle. Under the Loss of Power section on Using a Generator Safely, the CPSC warns that you must keep generators outside and far from the home and any other buildings, not tucked just inside a garage door or under an awning where exhaust can drift back indoors. A separate alert tied to Tropical Storm Helene urges consumers to keep their guard up as the storm continues its path of destruction and again reminds you that portable generators should never be used indoors or in the garage, because storm conditions that drive you to seek shelter for the machine are the same conditions that trap exhaust around your home.

What other safety agencies say about “cracked door” setups

Federal workplace safety regulators echo the CPSC’s stance, and they are explicit about the “cracked door” scenario. In its guidance on Using Portable Generators Safely, OSHA states that you should Never use a generator indoors or in enclosed spaces such as garages, crawl spaces, and basements, and adds a critical NOTE that Open windows and doors may not prevent CO from building up when a generator is located in an enclosed space. In other words, the very workaround many people rely on is the one OSHA is warning you not to trust.

State and local safety officials reinforce that message in plain language. A Texas advisory on how to use a generator safely tells you to keep the unit Outside, away from doors, and says Never use a generator indoors, adding that Even if the door is open, a generator in the garage can fill your home with carbon monoxide. A city level bulletin titled Gasoline Generators Produce Carbon Monoxide explains that Generators must always be used outside, never inside, including in the garage, even with the door open, and urges you to avoid placing them near windows, doors, or vents where exhaust can be drawn back into the building.

Real-world tragedies that keep repeating

The danger is not theoretical. After the snowstorm that ravaged Connecticut in November 2011, unintentional CO poisoning accounted for 18% of all storm related deaths, a figure that reflects how many people tried to improvise with generators and other fuel burning devices. That same analysis notes that some homeowners placed generators in garages or too close to the house to avoid risking water or wind damage, only to create a far deadlier hazard inside their walls. The pattern is clear: when you prioritize keeping the machine dry over keeping exhaust away from your living space, you shift risk from property to people.

Federal safety officials see the same story play out after hurricanes and tropical storms, which is why they keep issuing Generator Danger Warning notices that stress how CO from a generator is deadly and can kill you in minutes. One such advisory notes that One generator produces as much CO as hundreds of idling cars, and that portable generators pose a serious risk when used indoors or in the garage, even for short periods. When you combine that output with a semi enclosed space like a garage, the result is a concentration of CO that can overwhelm you before you have time to react, especially if you are already exhausted from dealing with storm damage.

How new labels and safety tech help, but do not save you from bad placement

In recent years, regulators have pushed manufacturers to make generators safer, but those improvements are not a license to ignore placement rules. A federal rule on Portable Generator Labels requires manufacturers to label portable generators with performance and technical data, and to include a prominent warning label that also includes pictograms showing that the unit must not be used in homes or garages. Those labels are designed to catch your eye in the moment you are about to start the engine, but they cannot override a decision to ignore them.

Some newer models also include automatic shutoff features that respond to high CO levels. Testing of these designs has found that in about 93 percent of scenarios, generators equipped with advanced sensors either shut down before CO reached dangerous levels or produced significantly less CO in the first place, which is a meaningful improvement. Yet even those tests assume the generator is used outside, not in a garage or enclosed porch. Safety features are there to backstop you if something goes wrong, not to make it safe to run a generator in a space that every official guideline treats as off limits.

What “safe placement” actually looks like

To break the habit of parking a generator in the garage, you need a clear mental picture of what safe use looks like. A practical rule is to think in terms of distance and direction. A Texas guide on how to safely set up and run portable generators advises that if you own a portable generator, you should place it outdoors at least 20 feet from your home’s doors, windows, or vents, and position the exhaust so it points away from the building. That same guidance reminds you that generator exhaust contains CO that is colorless, odorless, and potentially deadly, so you cannot rely on your senses to tell you when the machine is too close.

Local safety officials add useful detail about how to make that setup work in cramped yards. The Englewood advisory that begins with the blunt statement that Gasoline Generators Produce Carbon Monoxide goes on to say that Generators must always be used outside, never inside, including in the garage, even with the door open, and suggests using extension cords rated for outdoor use to bring power into the home while keeping the machine far away. It also notes that you should avoid trying to “vent” a generator with a fan or homemade ducting, because those systems are not designed to handle hot exhaust and can fail or leak, sending CO right back toward your living space.

Planning ahead, from CO alarms to federal oversight

Safe generator use is not just about where you put the machine on the day the power fails. It starts with planning, equipment, and paying attention to the broader safety ecosystem around you. At home, that means installing CO alarms on every level of your house, testing them regularly, and making sure everyone in your household knows that if an alarm sounds, they must go outside immediately and then call 911, as the CPSC’s Carbon Monoxide Information Center advises. It also means rehearsing where the generator will sit, how cords will run, and who is responsible for checking that it is at least 20 feet from any opening.

At the national level, the Trump Vance administration’s Consumer Product Safety Commission has signaled that it is taking product hazards seriously. In a statement from WASHINGTON, Sept 18, 2025, officials said that Today the Consumer Product Safety Commission announced it has surpassed a Biden era recall record more than 100 days ahead of schedule, underscoring a broader push to address dangerous consumer products before the end of the calendar year. That enforcement posture supports tougher rules on generator labeling and performance, but it does not change the physics of CO. Even with better oversight, clearer warnings, and smarter hardware, your safety still hinges on one non negotiable choice: keeping the generator outside, never in the garage, no matter how wide you think that door is cracked.

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*This article was developed with AI-powered tools and has been carefully reviewed by our editors.