CO Health Effects: Why the traditional PPM chart no longer tells the whole story

For years, the “CO Health Effects by PPM” chart helped people understand how carbon monoxide (CO) exposure impacts the body.
It was simple, visual, and easy to reference, and it became one of our most visited pages.

But new research and real-world data tell a different story. The truth is that carbon monoxide exposure doesn’t follow charts.

It follows conditions: who’s in the space, how much CO is present, and how long it goes unnoticed.

⚠️ Important: The chart below remains for historical reference only. It represents earlier assumptions that no longer capture how CO affects people in real-world settings.

For today’s most accurate understanding, continue below.

The Legacy CO Health Effects Chart

Note: This chart assumes that everyone reacts the same way to carbon monoxide, regardless of age, health, or the environment in which exposure occurs.

It’s a useful reference, but it doesn’t reflect the variables that make every CO incident unique.

Why The Health Effects Chart Is Incomplete

While helpful for raising early awareness, the traditional chart only measures two factors:

Air concentration (PPM)
Length of exposure

Those are important, but they’re not the whole picture.

Real-world carbon monoxide events in schools, homes, and workplaces show that risk and symptoms vary dramatically depending on other conditions.

For example:

A small, enclosed classroom fills with CO faster than a large gym.
A child or pregnant person absorbs CO faster than a healthy adult.
Even low levels can become dangerous if exposure lasts long enough.

That’s why it’s time to look beyond the chart.

Symptoms of carbon monoxide exposure mimic other ailments

One of the most dangerous things about carbon monoxide is that you can’t see, smell, or taste it, and its symptoms often mimic common illnesses. Many people don’t realize what’s happening until it’s too late.

Symptoms can develop slowly or suddenly, depending on how high the CO levels are, how long someone is exposed, and who is breathing the air.

Carbon monoxide exposure, toxicity, and poisoning symptoms

These may appear within minutes or hours of exposure:

Headache
Dizziness or lightheadedness
Nausea or upset stomach
Fatigue or weakness
Shortness of breath
Confusion or trouble concentrating
Blurred vision
Chest pain or irregular heartbeat
Vomiting
Loss of coordination
Disorientation or confusion
Fainting or collapse
Loss of consciousness

⚠️ Important: If multiple people in the same area begin feeling unwell at the same time — especially with flu-like or dizzy symptoms — it may be carbon monoxide. Leave the area immediately, get fresh air, and call 911.

To replace the outdated chart, CO Safe Schools developed The CO Effect Model — a modern way to understand how CO exposure truly affects health.

The CO Effect Model recognizes that carbon monoxide risk depends on three overlapping factors:

1. Unique Biology – Every individual's body reacts differently based on age, health, pregnancy, or medical conditions.
2. PPM Level (Air Concentration) – How concentrated CO becomes in the air, influenced by the size and ventilation of the space.
3. Amount of Time – How long someone is breathing that air, allowing CO to build up in the body.

Each factor alone is a risk. Where they overlap, those risks multiply and at the center lies the greatest health impact.

Why the CO Effect Model Matters

Understanding CO risk through The CO Effect Model helps us make smarter choices about prevention, protection, and response.

It explains why detection is critical in schools, daycares, and campuses.
It helps medical and emergency professionals respond more accurately.
And it empowers educators and community members to recognize the real conditions that create risk.

CO safety isn’t just about numbers, it’s about people.