Back when I was still masking on the subway for covid (to avoid missing things) I also did some air quality measuring. I found that the subway and stations had the worst air quality of my whole day by far, over 1k ug/m3, and concluded:
Looking at the graph in the linked air quality post, it looks like pm2.5 peaks below 100 ug/m3. Unless I'm reading wrong, it's the CO2 axis / line which briefly exceeds 1000 (ppm)?
Looking at the graph in the linked air quality post, it looks like pm2.5 peaks below 100 ug/m3. Unless I'm reading wrong, it's the CO2 axis / line which briefly exceeds 1000 (ppm)?
You're totally right, whoops! I'll take some new measurements, and if it's still in that range I don't think that warrants masking.
Follow-up: https://www.jefftk.com/p/subway-particle-levels-arent-that-high