Comment by jefftk
3 years ago
As the article explains, unless you're using the purifier to filter the air coming into a space, small differences in the purifier output PM2.5 level don't matter. If the output has 99% lower PM2.5 than the input vs 100% lower, that's dwarfed by all the existing particles that the output is about to be mixed back in with.
The output air of 0 vs 15 ug/m^3 is not negligible difference, especially when the air outside is 200+ during wildfires. The reality is, the great output air of Blueair filter + 350 cfm CADR is a pretty big difference. My indoor ambient air was about 10-15 ug/m^3 compared to 30-40 using the other solutions.
The difference between an output of 0 and 15 ug/m^3 with an input of 200 ug/m^3 is negligible when considering the performance of the filter in the room. Let's walk it through, imagining 1000 CF room and a flow rate of 250 CFM, and comparing something that's 100% effective (0 ug/m^3 output) vs 92.5% effective (15 ug/m^3 output).
At t=0 your room has a pm2.5 of 200 ug/m^3. At t=1min it has filtered 250 CF which is at either 0 or 15 ug/m^3. The remaining 750 CF is still at 200 ug/m^3. The air in the room is now either:
Repeat this 20 times to simulate 20min and the room is at at 0.6 ug/m^3 in the first case vs 1.1 ug/m^3 for the second. The absolute difference is never larger than 7 ug/m^3 (at minute #4), and quickly becomes tiny.
> the great output air of Blueair filter + 350 cfm CADR is a pretty big difference. My indoor ambient air was about 10-15 ug/m^3 compared to 30-40 using the other solutions.
My guess is your other solutions had a much lower flow rate (and hence a much lower CADR). What are you comparing to?