Unknown Winter Threat: Why Carbon Monoxide Dangers Spike When Temperatures Drop
Posted by Saloni Mahapatra on Jan 30th 2025
Winter brings colder temperatures, shorter days, and the need for extra warmth and power. While most people look forward to cozy nights by the fire and holiday celebrations, there is also a hidden danger that increases during the colder months: carbon monoxide (CO) exposure. CO is known as the “invisible killer” because it has no color, taste, or smell, making it undetectable to our senses. This also makes it hard to know when you are being exposed to it.
What is Carbon Monoxide?
Carbon monoxide (CO) is a gas produced when fuels like gasoline, natural gas, propane, or wood don’t burn completely. The Centers for Disease Control and Prevention (CDC) also warns that CO poisoning can be caused by many everyday appliances, including stoves, heaters, and portable generators. According to the U.S. Consumer Product Safety Commission (CPSC), carbon monoxide poisoning is responsible for over 400 deaths and 20,000 emergency room visits annually in the United States.
Carbon monoxide exposure symptoms can range from mild to severe and may include:
- Mild Exposure: Headache, dizziness, nausea, vomiting, fatigue, confusion.
- Moderate Exposure: Weakness, shortness of breath, blurred vision, difficulty concentrating.
- Severe Exposure: Loss of consciousness, chest pain, seizures, or even death.
When Do Carbon Monoxide Incidents Increase and Why?
The National Fire Protection Association (NFPA) reports that winter months—especially from December to February—see a higher number of carbon monoxide-related incidents.
Several factors contribute to the increase in carbon monoxide incidents during winter:
- More Use of Heating Systems and Appliances: When temperatures drop, people turn on their heaters, furnaces, and fireplaces. Many of these systems burn fuel such as gas, oil, or wood, which can produce carbon monoxide if they malfunction or aren’t properly vented.
- Closed Windows and Poor Ventilation: In the winter, homes are sealed tightly to keep heat in, and windows remain closed to avoid letting warm air escape. While this helps maintain a comfortable indoor temperature, it also reduces ventilation. Without adequate airflow, CO that is produced indoors cannot escape and can build up to dangerous levels.
- Reduced Carbon Monoxide Dissipation: According to the U.S. Environmental Protection Agency (EPA), cold weather conditions also make it harder for CO to dissipate. In cold weather, the density of the gas increases, and this makes it easier for CO to linger in the air. When it is trapped indoors, such as when a portable generator is run in a shed or garage, there’s a greater risk of exposure to dangerous levels of carbon monoxide.
- Increased Use of Portable Generators: Winter storms and power outages are common during colder months, and many people rely on portable generators to keep lights, heat, and other essentials running. However, when used improperly, portable generators can be a serious source of carbon monoxide.
The Connection Between Portable Generators and Carbon Monoxide
Portable generators are often used during winter power outages to keep essential appliances running, especially during extended power outages due to winter storms. While these generators are a valuable tool, they can pose a significant carbon monoxide risk if not operated correctly.
Portable generators run on gasoline, propane, or diesel, and they produce carbon monoxide as a byproduct of combustion. If these generators are used indoors or in enclosed spaces, such as garages or basements, the carbon monoxide they produce can quickly accumulate. In winter weather, when CO density increases, this can lead to lethal levels of CO in just minutes. Even when portable generators have auto-shutoff CO-sensors, the released CO remains in the air for long after the generator shuts off.
Unlike cars and other automobiles – which have catalytic converters to reduce the amount of harmful exhaust emissions – most portable generators do not have technology to effectively reduce carbon monoxide output. This means that carbon monoxide emissions from portable generators can reach toxic or fatal levels in mere minutes , especially in enclosed spaces like garages or sheds. To put things into perspective, during a winter power outage, a 7.5 - 10-kilowatt generator is recommended to continue home heating and other electric operations. Below is a comparison that shows carbon monoxide emissions in an hour from a portable generator versus other common CO-releasing equipment:
- Portable Generator: ~500-4000 g/hr CO emissions
- Idling Mid-Sized 2010s Sedan: 20-40 g/hr CO emissions
- Lawnmower: 70-100 g/hr CO emissions
- Fireplace: 10-80 g/hr CO emissions
According to the CPSC, portable generators are responsible for more than 40% of CO-related deaths caused by consumer products. It is crucial that generators are used outside and a safe distance away from doors, windows, and vents where the gas could enter the home. Even when portable generators are operated outdoors, people often make the mistake of placing them too close to a building or in areas where CO can enter the home, leading to risk of CO exposure and poisoning. Some people may think that placing the generator in a garage or near a window will keep the cold out, but this can be deadly.
How Can Portable Generators Be Operated Safely in the Winter?
To ensure your portable generator is used safely and does not put you at risk for carbon monoxide poisoning, follow these guidelines:
- Always Operate Generators Outdoors: Portable generators should always be used outdoors in an open space where there is plenty of airflow. Never use a generator inside your home, garage, or shed—even if the doors or windows are open. Even a small amount of carbon monoxide can accumulate and cause serious harm. GenTent recommends placing your generator at least 20 feet away from any windows, doors, or vents. Consumer Reports recommends covering your generator with a generator tent or cover like the GenTent to protect the generator against winter weather.
- Face Running Generator Exhausts Away From Open Windows or Vents: CO can enter through windows, doors, or vents. Make sure your generator is positioned far enough away from any openings in the home with the exhaust positioned away from doors and windows.
- Install Carbon Monoxide Detectors: Install a carbon monoxide detector in your home, especially near sleeping areas. This can provide early warning if CO levels start to rise. The CDC recommends installing a battery-powered or hard-wired carbon monoxide detector and checking the batteries regularly.
- Properly Maintain Your Generator: Regular maintenance is essential for safe generator operation. Make sure to follow the manufacturer’s maintenance instructions and keep your generator clean and in good working order. A well-maintained generator is less likely to emit harmful amounts of carbon monoxide.
- Use Extension Cords Wisely: If you need to run an extension cord from your generator to your home, make sure it is rated for outdoor use and is long enough to keep the generator a safe distance from your house. Never use indoor-rated extension cords, as they can overheat and pose a fire hazard.

Why Is a GenTent Generator Running Cover Necessary for Safe Winter Portable Generator Operation?
GenTent generator running covers are engineered to protect your portable generator from harsh winter conditions while allowing it to operate safely. These covers are made from durable, weather-resistant materials that shield your generator from rain, snow, and freezing temperatures. But beyond just keeping your generator safe from the elements, GenTent covers also help ensure your generator stays ventilated, which is crucial for preventing carbon monoxide buildup.
Here’s why a GenTent cover is a smart investment for winter portable generator operation:
- Allows Safe Ventilation: The GenTent cover is engineered to protect your generator while still allowing proper airflow. This ensures that CO produced by the generator can safely escape into the air, preventing dangerous buildup of the gas.
- Protects Your Generator in Cold Weather: The cover keeps your generator safe from snow and ice, ensuring that you can use your generator safely outside and 20 feet away from the house even in freezing temperatures and wet weather. Without protection, cold weather can cause damage to your generator, making it less reliable during power outages, and wet weather can cause electrical damage.
- Easy to Use: The GenTent cover is easy to install and doesn’t obstruct the generator’s vents or exhaust. It’s designed to provide year-round protection without compromising the performance or safety of your generator.