Posted by: Francis Koster Published: January 23, 2024

Stuffy Air in Classrooms Can Lower a Student’s Learning and Test Scores (January 23, 2024)

Did you know that stuffy air (low oxygen levels) in classrooms can lower a student's learning and test scores as much as two letter grades?

Air stuffiness (indoor air quality) is usually measured by using a meter to measure Carbon Dioxide. The higher the Carbon Dioxide, the lower the Oxygen. The meter counts Parts Per Million (PPM) of Carbon Dioxide in the air.

Put 20 kids in a classroom with no outside fresh air input and their learning and test performance drops significantly as the day goes on.

Below is one study (among many) that shows the impact on students' test scores of high Carbon Dioxide (CO2)/low Oxygen (O2).

The higher the concentration of CO2 in a classroom, the more parts of the brain do not work well. A visible clue is when several kids are nodding off at the same time.

Why Does Carbon Dioxide rise in a classroom?

More than half of all North Carolina schools have high CO2 levels, and as a result North Carolina is among the lowest ranked K-12 school systems in America.

How did this situation arise? Two main causes:

1) A large number of our older schools were built when the only way to bring fresh air into a classroom was open the windows. When energy costs started to rise rapidly in the 1970's, facilities management staff around the world began to lock windows, seal doors, lower air conditioning fresh air intake, and take other steps to reduce energy consumption and costs. Goodby fresh air.

2) In some states, construction costs and building maintenance costs are paid for by the state, distributed equally on a per student basis just like instruction costs. In other states, like North Carolina, building construction and maintenance are largely the responsibility of the local school district.

In North Carolina, lower than average income school districts means low facilities budgets, lower indoor air quality, lower learning, and lower property values. Through no fault of the teachers, the school system (and the future of the students) declines.

High income school districts mean higher real estate property values, higher school system budgets, and results in still higher school construction and maintenance budgets, better indoor air quality and higher standardized test scores, and teachers with good reputations.

Lower learning due to poor indoor air quality has nothing to do with how well the teachers are doing their job - but they get blamed.

Our partner organization, The Pollution Detectives, Inc. (a North Carolina 501-c-3) has been loaning (for free) simple-to-use CO2 meters since 2017 to North Carolina School systems. If you are interested, you can borrow and quickly install them to do your own Indoor Air Quality survey. The meter sends its data to us, and we send the report back to you. We sign confidentiality agreements before you begin to use the meters, and can furnish you references from other institutions we have worked with.


If you are interested in exploring this possibility, go to,

and read the material in the column on your left: "Is your school’s indoor air quality lowering learning?"

A link exists at the top of the website there to file a form to borrow equipment.



A change of subject

Regarding hearing and vision - one of our tech staff (that would be me) messed up. Last week's newsletter contained a bad link, so all of you who tried to express interest in possibly working together on a pilot project to do mass surveys of students for hearing and vision loss were unable to do so.  Please try again by sending an email to:

Unlike other states, North Carolina does not require annual testing of K-12 vision or hearing after early grades, even though it is well known that around 20% of students develop these clinical conditions during puberty and beyond. That is around 300,000 K-12 public school students! (3) As a consequence, an enormous number of students learn below their mental ability. These problems compound as the student’s early learning deficit hinders upper grade level learning, and if the student attends a school with poor indoor air quality, compounds the situation, leading again to higher drop-out rates, lower standardized test scores, lower statewide rankings, and lower property values in the school’s neighborhood.

Fixing this can be a win-win for the student, their family, and our society.

The first step to grab this opportunity is to conduct what is called a “Mass Survey” – not a “Screening” (which is a word with legal and bureaucratic meaning). A “Mass Survey“ has a goal of doing a quick test of as many students as possible, and identifying those students who should be referred to a licensed clinical professional for a “Screening” .

It is possible to do “mass surveys” for both hearing and vision by having students play 5-minute computer games on I-pads, laptops, or desktops computers. The software is free, and the survey can be done by college student or adult volunteers.

We want to demonstrate the impact of this kind of effort and are looking for partners that we can work with to do a pilot project during which we would design the protocol including parental consent, referrals to licensed clinical professionals, and evaluate which software to use.  We will then test a pilot cohort of students.

We are prepared to provide a few thousand dollars of financial support to support one partner school system or community organization so they can compensate a member of a planning team who will also be a Head of Project Volunteer Recruitment. Working together we will locate the needed free computer games, develop a protocol, and do training. Once we complete the pilot project, the learnings will be shared with all school systems in North Carolina.

If you are interested in learning more, and possibly working together on this project, send us a note expressing your interest to:

You can read more about this topic here:






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Francis P. Koster Ed.D.

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