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Chlorine Gas vs. My Sinuses: A Battle of Sweat, Tears, and Snot

Imamura here. Something happened at a small experimental vertical farm that permanently put me off the smell of chlorine.

The Big Clean

More people than you’d expect love the smell of a swimming pool. That feeling of standing on scorching asphalt in the blazing summer heat, shifting your weight from foot to foot, desperate to get in the water.

I used to love that smell too. Chlorine’s smell, to be precise.

I said “used to” — past tense. If you’ve already guessed where this is going, you’re ahead of me.

This is a story from when I was working at a small experimental vertical farm. The facility always had vegetables growing, and it was rare for every crop to reach harvest at the same moment. In other words: fully occupied, every bed, all the time.

But one day, everything came in at once. Experimental or not, it’s still a living environment. The accumulated grime and bacteria needed to be dealt with before the next run. There was no getting around it — time for a proper deep clean.

When I peered into the nutrient reservoir, it was dirtier than I’d imagined. Fine root fragments and something resembling algae had settled from all that cycling nutrient solution. I could see this was going to take real work.

The Remaining 10%

The final stage of any cleaning is sanitizing.

What I used was sodium hypochlorite — a chlorine-based bleach, the compound behind that distinctive pool smell, and the same thing used to disinfect swimming pools.

Ideally, sodium hypochlorite should go in only after the tank has been fully drained of nutrient solution. But the equipment I was cleaning had a design flaw: even after draining, about 10% of the nutrient solution stayed trapped in the tank.

Drain it, and there’s still a lot left.

The right move would have been to flush the nutrient reservoir with water and drain it — several times over. But the facility had the next experiment starting the following day, and I was feeling the pressure.

That’s when the thought crept in: “There’s nothing I can do about it.”

Looking back now, that was the moment I should have stopped. When that phrase surfaces on the floor, it’s almost always a sign that someone is about to let something slide.

Eyes and Nose: Both Hit

I added the sodium hypochlorite and switched on the circulation pump. The liquid started moving through the system.

At first, everything seemed fine. If anything, I was thinking: smells like a pool — kind of nostalgic. I wasn’t worried. When you’re not worried, your judgment tends to go soft.

About ten minutes in, my eyes started feeling off.

Five minutes after that, my nose started running.

From that point on, the air felt different in a way I couldn’t ignore. Every breath left a burning sensation deep in my sinuses. My eyes felt like a thin film had been stretched over them. The pump grew strangely loud; everything else in the room faded into the background.

What was happening was a very simple chemical reaction:

Remaining nutrient solution (acidic) + sodium hypochlorite (alkaline) = chlorine gas

I must have covered this in school chemistry. I’d completely forgotten.

Under normal conditions — fully drained tank, proper dosage — there would have been no problem. But this time, nutrient solution remained. The acidity was already high, and I may have added too much sodium hypochlorite on top of that. I had assembled, entirely on my own, exactly the textbook conditions for chlorine gas production.

I wanted to stop. But the next experiment was starting tomorrow. I couldn’t walk away with the job half done.

I threw the doors open, but the chlorine irritation didn’t let up. My eyes were red and bloodshot. My mask was soaked with a mixture of snot and tears. Every breath left my nasal passages burning. The next task, ventilation, tomorrow’s experiment, runny nose, eyes hurting — no — flush this section first — my thoughts were fragmenting into pieces.

The Only Casualty: My Nose

What made it worse was that I suffer from chronic sinusitis.

What happens when chlorine gas enters the sinuses of someone with the complicated, layered nasal passages of a chronic sinusitis sufferer? Medically speaking, it might be interesting. As the patient, I had no headspace to find it interesting.

After that incident, my nose was completely non-functional for roughly two weeks. Waking up each morning with severe dry mouth told me immediately that I’d been mouth-breathing all night. I came to deeply appreciate what a nose can do — something I’d taken entirely for granted until it was gone.

In the end, the cleaning got done and the next day’s experiment started on schedule. The facility survived intact. The only casualty was my nasal cavity.

What I learned from this experience is clear:

1. Never add sodium hypochlorite directly to nutrient solution
2. Always fully drain the nutrient solution before sanitizing
3. “There’s nothing I can do” is a danger signal
4. Chemical reactions produce their results honestly, without caring about your feelings

Especially number three. If the thought “there’s nothing I can do” crosses your mind and you find yourself wanting to push through anyway, treat it as an alarm — an absolute signal to stop.

To this day, I instinctively pick up my pace near swimming pools. Even writing this now, I can bring back that burning sensation deep in my sinuses with very little effort.

To everyone working in a vertical farm: cleaning matters. But please don’t try to override the laws of chemistry because you’re short on time. You don’t truly appreciate healthy nasal passages until you lose them.