“Difficulty Breathing at CO2 Concentration of 1000ppm!?”

Hello everyone! I’m Shohei.
This column is written mainly based on my field experience.
After being on site for over 10 years, there are truly many things that happen. I’m writing about things I remember, as they come to mind.
Well, please read it casually, like “Oh, so that’s how other factories are.”

“The CO2 Concentration in the Factory is 1000ppm”

“The CO2 concentration in the factory is 1000ppm.”
What image comes to mind when you hear this statement?
“Oh, that’s a good environment for plants”
“1000 seems like a big number, could it be dangerous?”
“What does ppm mean?”
Actually, I never expected that this casual explanation would one day suddenly cause such drama.

Common Experiences in Plant Factory New Employee Training

When new staff join the plant factory, I always give them a facility tour following the same routine.
“This is the seedling room”
“Final transplanting is done here”
“This is the harvesting area”
And I always make sure to explain that “In this facility, we raise the CO2 concentration to 1000ppm to promote plant growth.”
Most new employees listen with an impressed look saying “hmm.” Honestly, for us veterans, this information is so routine that we don’t pay particular attention to it.

The Incident That Day

It was an ordinary Tuesday afternoon.
New employee Yamada (pseudonym) suddenly turned pale and collapsed while working in the factory. Just like a scene from a drama.
“Yamada! Are you alright?!”
We quickly took him outside and watched over him while having him drink tea in the break room. After about 10 minutes, his complexion returned to normal.
“I’m sorry… I suddenly felt short of breath…”
Yamada said, looking embarrassed.
When I asked, “Should we call an ambulance?” he replied, “No, I’m fine now,” so I had him leave early just to be safe.

The Unexpected “Culprit”

The next day, Yamada came to work in good spirits. His health check showed no problems. So why did he collapse?
As we talked through various things, a shocking fact came to light.
“Actually… when I heard the CO2 concentration was high, I kept thinking I might have trouble breathing.”
What! The culprit was his “assumption.”
“But how high is 1000ppm? It’s harmful, right?”
That question made me realize something. Indeed, for the average person, what the value “1000ppm” means is completely unclear.

The Magic Phrase “About the Same as Inside Your Home”

From that day on, I always added one sentence to my explanation for new employees.
“The CO2 concentration in the factory is 1000ppm. This is about the same concentration as inside your home.”
With just one phrase, I could see the expressions of new employees change from “???” to “I see~”.
In fact, the CO2 concentration in a closed room easily reaches 1000ppm just from human breathing. Even the bedroom in your home where you spend every day might easily exceed 1000ppm by morning.

The Power of Assumption Exceeds Science

The human brain is interesting; just believing “this might be dangerous” can actually cause physical discomfort. This is a phenomenon called the “nocebo effect,” the reverse version of the “placebo effect.”
Yamada, from his assumption that “high CO2 concentration = difficulty breathing = danger,” actually felt short of breath and temporarily collapsed.
When you think about it, we don’t usually pay attention to the CO2 concentration in the atmosphere. Even when told that the CO2 concentration outside is about 400ppm and inside the factory is 1000ppm, hardly anyone can actually sense that difference.

The Power of Words

What I learned here was that “explanations of technical terms need everyday examples.”
The phrase “about the same as inside your home” gives a much stronger sense of reassurance than just the number “1000ppm.”
Now when explaining to new employees, I can’t help but go into more detail.
“The CO2 concentration in the factory is 1000ppm. This is about the same concentration as inside your home. For reference, it’s usually around 4000ppm inside submarines, and about 5000ppm on the International Space Station, but people can live there without problems. Effects on the human body start to appear from about 5000ppm and above, so please don’t worry.”
…When I explain in this much detail, some new employees now smile and say, “So we’re like astronauts!”

Common Experiences in Plant Factories

Actually, this “physical discomfort due to assumptions” might be one of the common experiences in plant factories.
High humidity environments, the special light of LEDs, the sound of circulating water… many people unconsciously feel stress in environments different from their usual ones.
Even so, with just the phrase “about the same as inside your home,” new employees’ anxiety almost completely disappears. It’s strange, isn’t it?
The power of “assumption” sometimes exceeds science—this was an unexpected lesson in human psychology that I learned at the plant factory.

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