Generator Emissions and CO Standards by State

Why CO standards matter for generators

Carbon monoxide (CO) is an odorless, colorless gas that can cause sudden illness and death if inhaled. The U.S. Consumer Product Safety Commission (CPSC) reports that more than 200 people in the United States die every year from accidental non-fire related CO poisoning associated with consumer products, and more than 100 of those deaths are linked to portable generators. These numbers highlight the severe risk that portable generators pose when used incorrectly, especially during power outages and after storms.

One portable generator produces the same amount of carbon monoxide as hundreds of cars, according to CPSC. This comparison underscores why CO safety standards are critical: they are designed to reduce the risk of poisoning when a generator is used correctly, even if it is placed outdoors. The CPSC also notes that CO can incapacitate and kill within minutes, so prevention through engineering and usage guidelines is the only effective approach.

For this reason, both federal and state regulators have focused on reducing generator-related CO deaths. While federal rules are still in the proposal stage, many manufacturers have already adopted voluntary standards that include CO detection and automatic shutoff. Understanding these standards helps you choose a generator that prioritizes safety and complies with current and future requirements.

Federal regulations and the proposed CPSC rule

In April 2023, the CPSC published a proposed rule, the Safety Standard for Portable Generators, in the Federal Register. The rule would require all portable generators to include a carbon monoxide shutoff system that automatically turns off the engine when CO levels reach a dangerous threshold, along with emission limits. This proposed rule, docket number CPSC-2006-0057, is not final, but it signals the direction of federal regulation. The comment period closed in June 2023, and the agency has continued to work toward a final rule.

The proposed rule references two voluntary standards: UL 2201 and PGMA G300-2018. These standards define CO emission rates and shutoff levels for portable generators. While voluntary now, they are the benchmark for evaluating a generator's CO safety. The Federal Register document provides extensive analysis of the hazard patterns and the effectiveness of these standards, including estimates of deaths and injuries that could be prevented if all generators complied.

Until the rule is final, there is no federal mandate requiring CO sensors on every portable generator. However, the CPSC strongly recommends choosing generators that meet these voluntary standards. In fact, many retailers and manufacturers have already adopted them because they recognize both the safety benefits and the likelihood of future regulation.

Voluntary standards and certifications

UL 2201 and PGMA G300-2018 are the primary voluntary standards for CO safety. They specify maximum CO emission rates and require a shutdown system if CO is detected. Generators that meet these standards typically carry a certification mark from a recognized testing laboratory, such as UL (Underwriters Laboratories) or another accredited organization. The presence of such a mark gives you confidence that the generator has been independently verified to meet the strictest CO safety criteria.

When shopping, look for models that explicitly mention CO sensor technology. The CPSC even has a rule proposal that would make these sensors mandatory. In the meantime, CO sensor generators offer the highest level of protection. For more details on how CO sensors work, see our CO sensor requirements article.

It is also important to understand that CO sensors are not the only safety feature. Some generators include a low CO emission engine design that reduces the amount of CO produced in the first place. Whereas a CO sensor reacts to dangerous concentrations, a low-emission engine prevents them. The best generators combine both approaches, meeting the emission limits of UL 2201 and also automatically shutting down if CO levels rise unexpectedly.

State requirements for generator compliance

Currently, there is no published list of states that mandate specific CO safety equipment on portable generators. However, the proposed federal rule would apply nationwide, creating a uniform standard. Until that rule is finalized, requirements can vary by state and local jurisdiction. Some states have adopted building codes that require CO alarms in homes, but these usually apply to the home, not the generator itself. Always check with your local building department or fire marshal for any applicable regulations before purchasing a generator.

In the meantime, the best approach is to choose a generator that meets voluntary standards. This ensures you are prepared for both safety and future compliance. You can also read more about emissions standards to understand the broader picture, including how emissions regulations affect the sale and use of generators in different regions.

It is worth noting that some states, particularly California, have stricter air quality regulations that apply to small engines. However, those regulations focus on smog-forming pollutants like nitrogen oxides and hydrocarbons, not specifically on CO. The CPSC rule is the primary federal effort targeting CO. Since the rule is not yet final, there is no state-by-state map of CO compliance requirements, but federal preemption would eventually apply if the rule is enacted.

Safe usage and CO detection

Even with a CO sensor, the CPSC and CDC strongly advise operating portable generators outdoors only, at least 20 feet away from windows, doors, and vents, with the exhaust facing away. Never use a generator in a garage, basement, crawlspace, or shed, even if doors and windows are open. The CDC also recommends that you use a battery-powered or battery backup CO detector in your home whenever a generator is in use. These simple steps can prevent the buildup of deadly CO inside your living space.

Install battery-operated CO alarms on every level of your home and outside sleeping areas. The CDC recommends checking detector batteries when you change clocks and replacing detectors according to manufacturer instructions. Knowing the symptoms of CO poisoning, which include headache, dizziness, weakness, nausea, and confusion, can also save lives. If you suspect CO poisoning, get outside to fresh air immediately and then call 911.

The EPA also emphasizes that CO poisoning can occur even after the generator is turned off, because CO can linger for hours in enclosed spaces. That is why it is so important to keep the generator far away from the house and to rely on alarms to warn you of any dangerous accumulation. Even if you use a generator with a CO sensor, you should never disable the sensor or rely on it as a substitute for proper placement and alarm use.

What to look for when buying

When comparing generators, prioritize models with built-in CO sensors and check for third-party certifications such as UL 2201. Consider the best CO sensor generators list for models that already meet these criteria. Also factor in your power needs, fuel type, and noise level. For many homeowners, a portable generator with CO sensing is the best balance of safety and versatility.

If you need lower emissions and quieter operation, an inverter generator is a good choice. For fuel flexibility, a dual fuel generator lets you switch between gasoline and propane. Review our buying guides for detailed comparisons of specs, runtime, and features. Remember that the most expensive generator is not necessarily the safest; look for the CO sensor and certification mark.

Finally, always read the owner's manual and follow the manufacturer's instructions regarding placement and operation. Even the most advanced CO sensor cannot protect you if you ignore safe usage guidelines. Use a generator as an emergency backup, never indoors, and always keep a working CO alarm nearby.

What to pick for your use

Questions

Are CO sensors required on all generators in the US?

Not yet. The CPSC has proposed a rule that would require CO shutoff systems on all portable generators, but it is not final. For now, look for generators that meet voluntary standards like UL 2201.

What is the 20-foot rule for generators?

Always place portable generators outdoors at least 20 feet from windows, doors, and vents, with the exhaust facing away, to prevent CO from entering your home. This recommendation comes from the CPSC and CDC.

What does UL 2201 mean?

UL 2201 is a voluntary standard for portable generators that sets limits on CO emissions and requires a shutdown system if CO is detected. It is one of the standards referenced in the CPSC's proposed rule.

How can I tell if a generator is CO compliant?

Check for a CO sensor and third-party certification marks like UL 2201. Many manufacturers advertise CO sensor technology on the box and in specs. You can also look for the PGMA G300-2018 certification.

What are the symptoms of CO poisoning?

Headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. If you suspect CO poisoning, get outside to fresh air immediately and call 911.

Will state laws change once the federal rule is finalized?

If the CPSC rule becomes final, it will apply nationwide, which would preempt conflicting state requirements. Until then, states may have their own regulations, but no state currently has a specific CO sensor mandate for portable generators.