The Hidden Rules That Shape CO Safety in Schools: Why Occupancy Types Matter More Than You Think

If you’ve ever wondered why carbon monoxide (CO) detection rules seem inconsistent across schools, daycares, churches, camps, and athletic facilities, the answer is this:

Buildings aren’t regulated by who uses them; they’re regulated by how the code classifies them.

And that classification, called an occupancy type, determines whether CO detection is required, optional, or never mentioned at all.

The problem? Most parents, teachers, and even administrators have no idea which occupancy type their building falls under, or how much that label controls the safety requirements inside it.

Before we dive into a relatable story, let’s break down what occupancy types actually mean in plain language.

What Are Occupancy Types? (A Layman’s Guide)

In the world of building codes, which is where carbon monoxide requirements live, every building is sorted into an “occupancy group.”

Think of it as the category that tells inspectors and fire marshals:

• how the space is used

• who is inside it

• how quickly people can evacuate

• how vulnerable the occupants may be

Those decisions directly impact:

• fire protection requirements

• mechanical ventilation rules

• sprinkler requirements

• means of egress

• AND carbon monoxide detection requirements

Here are the ones most relevant to childhood, school, sports, and campus life:

Group R — Residential

Where people sleep.Small home daycares (R-3), dorms (R-2), cabins at camp — places where CO risk is high because people are unconscious and unable to respond fast.

Group I-4 — Institutional

Where young children (especially under 2.5 years old) are supervised and need help evacuating. This triggers stricter safety rules.

Group E — Educational

Where learning happens for more than five children over age 2.5.Covers K–12 schools and some structured early childhood programs.

Group A — Assembly

Large gatherings — gyms, auditoriums, churches, cafeterias, natatoriums. Many CO incidents happen here because ventilation is complex and equipment loads are high.

“Mixed Use”

One building with multiple occupancy types.For example: A church (A-3) with a daycare (I-4) operating in the same wing. This is where safety rules get complicated fast.

Carbon monoxide risk is inherent in every learning center, sports complex, and place of worship – yet each space has different CO safety requirements.

Meet Leo: One Child, Dozens of Buildings With Different CO Safety Requirements

To understand how confusing this really is, let’s follow one child, Leo, as he grows up in a typical American community.

Every place Leo learns, plays, worships, and sleeps has a different occupancy type… and different CO requirements, even within the same state.

Age 1: A Daycare in a Church Basement

Leo spends his days in a church-based daycare that operates independently of the Sunday services. Even though the daycare is inside a church, it isn’t automatically treated as “church use.”

Codes often classify the occupancy type as:

• Group I-4 if caring for children under 2.5

• Group E if older children

• Group A-3 if only used during services

Three possible occupancies.Three completely different CO requirements.

Parents assume: “The church must have CO detectors.”

Reality: Not necessarily.

Age 4: A Preschool in a Standalone Building

Now Leo attends a commercial preschool. That preschool is Group E.

But because he’s four years old and can self-evacuate:

• detection rules often become less strict

• the building may follow older code editions

• the owner may not be required to add CO detection retroactively (this was the loophole that allowed carbon monoxide to poison my children, along with 80 others in Virginia in 2020).

  
  

Again: Parents assume safety is automatic.

But code only follows labels, not logic.

Age 6–10: Leo's Elementary School

Leo moves into an elementary school with:

• boilers

• kitchens

• rooftop units

• attached gyms

• buses idling nearby

The building is Group E, but the gym, cafeteria, and auditorium could be Group A-3 — even though they are under the same roof.

Based on the state, or the building codes used, CO detection may or may not be required, even if CO could spread through the entire building.

• in mechanical rooms

• in kitchens

• in classrooms

• in gyms

• in hallways
  

If there are CO detection requirements, they are usually tied to a fuel-fired appliance being present, and the detection devices being positioned relevant to that space – not throughout the building itself.

Age 11–13: Middle School and Sports Begin

Leo starts soccer, wrestling, and Boy Scouts.

He now spends time in:

• a gymnasium (A-3)

• sports complex (A-4 if spectators are present)

• locker rooms (A-3)

• weight rooms (sometimes E, sometimes A-3)

• summer camp with the Scouts (A-3, R, and E on site)
  

Each zone has a different code recipe.

CO from a malfunctioning rooftop unit in the gym may not be detected until it reaches an area with an actual detector, if the building has any.

Age 14–17: High School, Labs, and Vocational Spaces

Leo’s high school includes:

• chemistry labs

• automotive tech classrooms

• wood and metal shops

• welding spaces

• a performing arts center

• multiple gyms
  

Every area can be a different occupancy classification.And because many of these are “specialty spaces,” they carry a higher risk for combustion, ventilation issues, or exhaust problems.

But unless the state has adopted newer code editions…CO detection is still not required everywhere. Keep in mind, too: this is the age where Leo gets a car or an after-school job, and can start traveling to other occupancy types on his own or with friends, without your supervision.

Age 18+: College Life

Leo heads to a university with:

• dorms (R-2)

• dining halls (A-2)

• lecture halls (A-3)

• labs (often B or F-1 type depending on use)

• athletic centers (A-3 or A-4)

• student unions (A-3 / Mixed Use)
  

Here’s the kicker: Some occupancy types require CO detection. Some don’t. Some only require it in certain rooms. Some depend on whether the jurisdiction amended the model codes. And students, the ones most at risk, have no idea.

Why This Matters

Following one child from daycare to college shows how fragmented CO safety really is.

Same child. Same community. Completely different rules depending on:

• age

• building category

• occupancy classification

• code edition adopted

• whether the state amended the code

• when the building was built

• what equipment is onsite

Carbon monoxide does not care about occupancy labels. But policy does. And that mismatch is why CO incidents continue to occur, and continue to harm hundreds of children and adults, every single year.

A Simple Truth

We believe that if a child can breathe in a space, that space should have CO detection, regardless of:

• occupancy group

• building age

• code edition

• use classification

• installed, fuel-fired appliances

But until the model codes catch up and states adopt them consistently, understanding occupancy types helps communities advocate for stronger safety.

Where is your child's life journey taking them?