@DOTsGtGrandbaby @IanRicksecker @mehdirhasan @nhannahjones @tylerblack32 @sdschools There are particle counters but it seems more complicated to count particles of different sizes and know which ones are important.
Nice thing about CO2 is low CO2 -> particle accumulation must be low (filtration is a bonus). With mid or high CO2 plus filtration, less clear.

@DOTsGtGrandbaby@IanRicksecker@mehdirhasan@nhannahjones@tylerblack32@sdschools有粒子计数器，但计算不同大小的粒子并知道哪些粒子是重要的似乎更复杂。
二氧化碳的好处是低二氧化碳->；颗粒积累必须低（过滤是一个额外的好处）。中高二氧化碳加过滤，不太清晰。