When I returned to teaching mid-pandemic, I bought a $250 CO2 meter to test my classrooms; people exhale CO2 so these levels are a good proxy for COVID exposure risk. Research predating COVID shows transmission of airborne infectious diseases is virtually eliminated if one can exchange indoor air to outdoor CO2 levels. The Brits learned a parallel lesson in the 1800's after several Cholera epidemics: Don't drink sewage water. Are we making a similar investment in indoor space ventilation, using heat exchangers to make outdoor air quality the indoor standard in all public spaces? No. We breathe the equivalent of sewage water, and accept common colds and now COVID as an unavoidable fact of life. Yes, we're that stupid.
There must be a similar meter that shows levels of CO. You don't just want an alarm, you want to measure your risk. CO is a byproduct of incomplete combustion, and bincho charcoal does burn more cleanly than alternatives. I've sat by live bincho fires in Japanese izakaya, and I've had live charcoal fires at my table in Korean BBQ restaurants, but I don't understand the risk.
Modernity is novel, which leads to mistakes. One is tempted to try things without twenty generations of experience, "Did my ancestors die doing this?" My favorite example is Alaskan natives who for generations fermented seal meat in seal skins, till someone had the bright idea "Why not just use a plastic pail?" Botulism is why not. Closer to home, one shouldn't use galvanized metals in a BBQ cooker. Who knew? One can't possibly know everything like this, so the fallback is to always be keenly aware of precedent.
There is precedent for burning bincho charcoal indoors, but I don't have ancestral wisdom here, and even that can be wrong. So I'd want a good meter. I get laughed out of fermentation forums for testing my hot sauce ferments with a pH meter, but who cares! We're talking $100.