How to Avoid Carbon Monoxide Poisoning in Your Car

avoiding carbon monoxide poisoning in a car
Avoiding carbon monoxide poisoning in your car starts with the exhaust, where a plugged or leaky system can get real dangerous really fast. Dimitri Otis / Stone / Getty

Carbon monoxide poisoning is a serious risk whenever carbon monoxide is released in an enclosed space, such as a home, garage, or car. Severe neurological damage may occur after only minutes of exposure, and people die from carbon monoxide poisoning in their cars every year.

The problem with carbon monoxide is that it is both odorless and colorless, and by the time you start to feel its effects, it may be too late. According to the Centers for Disease Control, 50,000 people are hospitalized each year, and 430 die due to accidental carbon monoxide poisoning.

Because you can’t see or smell carbon monoxide, the best way to avoid accidental poisoning is to prevent exposure in the first place.

Reducing the Risk: A Checklist

While the threat of exposure to carbon monoxide poisoning in your car is very real, you can take some extremely easy precautions to reduce the danger to almost nothing at all. These range from making sure that your exhaust system is in good working order to avoiding certain dangerous situations. You can even install a portable carbon monoxide detector for extra safety. Consult this checklist:

  1. Regularly inspect and repair your exhaust system. Leaks in the exhaust system can allow carbon monoxide to enter your vehicle. Exhaust system leaks between the engine and the catalytic converter are especially dangerous.
  2. Regularly inspect your emissions system and make sure your engine is tuned. The concentration of carbon monoxide in the exhaust of modern vehicles is relatively low. If the engine is out of tune or the emissions system is malfunctioning, the carbon monoxide levels may skyrocket.
  3. Avoid driving a car with holes in the floor or trunk, or with the trunk or liftgate open. Any holes in the underside of your vehicle may allow exhaust fumes to enter your vehicle. This is especially dangerous if the exhaust system has leaks, or you sit in traffic a lot.
  4. Never allow passengers to ride in a truck bed covered with a canopy. Truck beds and canopies aren’t sealed as well as passenger compartments. Carbon monoxide levels can spike under a canopy without the driver noticing.
  5. Avoid running your car inside a garage or any other enclosed space. Even if the windows are rolled up or the garage door is open, the carbon monoxide inside the vehicle is likely to reach dangerous levels.
  1. Never run your engine if the vehicle is partially covered in snow. If the tailpipe is partially obstructed, exhaust may be redirected underneath the vehicle and enter the passenger compartment.
  2. Don't repeatedly start and stop your engine in an effort to stay warm. This can actually generate more carbon monoxide than just running it continuously.
  3. Install a 12-volt or battery-powered carbon monoxide detector. You can’t see or smell carbon monoxide, so the only way to be totally safe is to install a detector.

Why Is Carbon Monoxide Poisoning So Dangerous?

When you breathe in, oxygen binds to your red blood cells, which then carry it throughout your body. Then, carbon dioxide is released when you breathe out, which frees up your red blood cells to pick up more oxygen from your next breath.

The tremendous danger inherent with carbon monoxide is that it binds to your red blood cells, too, just like oxygen. In fact, the hemoglobin in your blood is more than 200 times more attracted to carbon monoxide than oxygen, so your blood can easily lose the ability to carry oxygen to the tissues in your body.

When that happens, the symptoms are typically nausea and headache, but severe tissue damage can occur if the exposure is strong enough or lasts long enough. If the concentration is high enough, unconsciousness will often occur before you notice any other symptoms. This is why it’s so important to avoid exposure to carbon monoxide in the first place.

How Does Carbon Monoxide Get in Your Car?

Internal combustion engines work by turning the potential energy contained in diesel fuel or gasoline into kinetic energy, but the process also results in a lot of byproducts that are expelled as exhaust gases. Some of these are inert, such as nitrogen, or harmless, such as water vapor.

Some other components of exhaust gas, such as carbon monoxide, hydrocarbons, and nitrogen oxides, can be extremely harmful to human health. So, while most of the compounds that make up exhaust are harmless, the fact is that your exhaust pipe also dumps poisonous carbon monoxide into the environment.

Under normal driving conditions with an exhaust system that's in good working order, carbon monoxide expelled from your tailpipe quickly dissipates to safe levels. But when any number of things go wrong, that can change very quickly.

How Emissions Controls and Exhaust Systems Affect Carbon Monoxide Poisoning

In modern cars and trucks, the levels of carbon monoxide produced by the engine are much higher than the levels that are actually released to the atmosphere. This reduction is accomplished through emissions controls that were introduced in the 1970s and continuously refined, so classic cars still put out a lot more carbon monoxide than any vehicle sold today.

When the emissions control system in a modern car or truck stops working correctly, the computer will usually detect that something is amiss, and the Check engine light will turn on. This is why it’s so important to find out why this light is on, even if the engine seems to run just fine.

The problem is that if the emissions system isn’t working correctly, you can end up with much higher concentrations of carbon monoxide in your exhaust than you would otherwise. A catalytic converter can actually reduce the amount of carbon monoxide, hydrocarbons, and nitrogen oxides by as much as 90 percent.

This is also why some exhaust leaks can pose such a huge problem. If an exhaust system has a leak ahead of the catalytic converter, exhaust gases with much higher levels of carbon monoxide may seep into the passenger compartment.

Why Enclosed Spaces and Carbon Monoxide Can Be So Deadly

According to the Occupational Safety and Health Administration (OSHA), 50 ppm is the highest concentration of carbon monoxide that a healthy adult can tolerate in any given eight-hour period. Concentrations beyond 50 ppm can cause serious harm and even death if the exposure lasts long enough.

At 200 PPM, a healthy adult can expect to experience symptoms such as dizziness and nausea after about two hours. At concentrations of 400 ppm, a healthy adult will be in mortal danger after about three hours of exposure, and concentrations of 1,600 ppm will induce symptoms within minutes and can kill within one hour.

Depending on the condition of the engine, and how well it is tuned, the concentration of carbon monoxide present in combustion gas will typically be between 30,000 and 100,000 ppm. In the absence of a functioning catalytic converter, that massive concentration of carbon monoxide can accumulate very fast.

Although a functioning catalytic converter will cut down on the amount of carbon monoxide drastically, that just means it will take longer to build up to poisonous levels. This is why using your car as a generator during a power outage can be dangerous, but even warming your car up in the garage can cause problems.

According to a study from Iowa State University, running a car inside a garage with the door wide open caused the carbon monoxide levels in the garage to hit 500 ppm in just two minutes. Furthermore, the concentration was still high enough to do harm a full 10 hours later.

Detecting Carbon Monoxide in Your Car

While maintaining your exhaust and emissions systems will go a long way to preventing carbon monoxide poisoning, and avoiding dangerous situations can reduce the risk even further, adding a carbon monoxide detector can provide even more peace of mind.

Most carbon monoxide detectors are designed for home or office use, but you can use the same basic technology in your car or truck. The important difference is that to be useful, an automotive carbon monoxide detector has to run on a 12-volt accessory outlet or battery power.

Also, detectors that are designed for use in your home or office might not be able to handle the temperature and humidity swings experienced in a car that is parked outside in different kinds of weather.

In addition to electronic carbon monoxide detectors that are designed for use in your car, another option is a biomimetic or opto-chemical sensor. These are typically stick-on sensor strips or buttons that don’t use batteries. Instead, they simply change color when exposed to carbon monoxide.