I built a battery-powered sensor kit to log air quality in random places. Here is what happens to CO2 in a packed vs empty movie theater (and where should I test it next?)
Hi, I'm Ovidiu. I'm building a startup from scratch and on my journey I want to raise awareness about what I find related to air quality.
I built a portable setup using a mini PC, a router, and some air quality sensors running off battery power. It lets me log environmental data in all sorts of places. I wanted to share some data from a couple of movies I went to recently. This is part of my effort to bring invisible elements surrounding us to the public.
When a crowd sits in a sealed theater for two hours, the air changes fast. Here is what the numbers looked like (I'll let you guess first; tap to reveal):
- Low attendance (10% full): >!CO2 averaged 544 ppm and stayed well below the 1000 ppm mark where air starts feeling stale.!<
- High attendance (90% full): >!CO2 averaged 1246 ppm, peaked at 1312 ppm, and stayed above 1000 ppm for the entire 165-minute screening.!<
Once CO2 crosses that 1000 ppm threshold, we start feeling sluggish, foggy, and sleepy. Add in the fact that temperatures climbed past 27°C (80°F) in both screenings, and your brain pretty much defaults to nap mode.
On the bright side, pm2.5 particulate levels and radon stayed low, so the theater's filters were doing their job. The main issue isn't filtering dust or pollen out, it's bringing in enough fresh outside air to dilute all the exhaled CO2.
If you want to check out the raw logs and breakdowns, I posted them here:
- Movie night - 10% attendance report: https://baseworks.tech/products/risk-assessment/samples/movie-night-few-people/
- Movie night - 90% attendance report: https://baseworks.tech/products/risk-assessment/samples/movie-night-medium-room/
I would love to run more experiments on behalf of the community. What public spaces, events, or transit options are you curious about measuring? Let me know what you want to see!
