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Non-profit. Helping businesses better protect their customers from viruses like SARS-CoV-2. Fix your air with the guides cleanairstars.com/steps.
Air filter recommendation tool (non-profit) at filters.cleanairstars.com
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There are many white labelled brands of these devices and so a variety of sources of replacement filters tend to appear.
This is an outdated list of sources simp.ly/publish/0P5fBm
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Several small air purifiers may be a better solution than one large one. You might think that this would improve the homogeneity of filtration in a room. But we've also built large purifiers to carry out a few tests, like this model with a capacity of 450 m3/h.
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It’s has a GB/T tested CADR at turbo speed of 600m3/hr at a reported 51.5dBA. The issue is that there is no mention on CADR and noise levels at the other 4 speeds which is what’s needed for it to be useful in the tool (unless noise isn’t an issue at 50dBA)
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If you find any send it through and it will be added to the tool
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From a single data point (e.g. high CO2), you can’t know the ventilation rate. The rate that the CO2 changes over time is required. That said, it can tell you something. For example, if the room is crowded and the CO2 is low, you can assume that the ventilation must be pretty good.
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Pricing and availability of devices is a year or two out of date. There are some newer DIY options missing too. Anyone can message this account with new devices and specs to be added
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Many manufacturers will inflate room sizes and CADR figures.
Before you buy an air purifier, always check the actual CADR figures and the recommended room size.
Visit the ENERGYSTAR database www.energystar.gov/productfinde...
Or check the @cleanairstars.com tool filters.cleanairstars.com
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The total views on the channel is approaching 10k, which is pretty wild for a channel dedicated to explaining how aerosol affects human health.
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You could also argue that a larger space/higher ceilings is somewhat protective as aerosols have more room to dilute into, but as mentioned they won’t necessarily dissipate as quickly as CO2.
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But importantly, it takes longer for CO2 to reach its steady state in a large space. Someone could be in a poorly ventilated space for a while before CO2 reveals poor ventilation.
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In a large space where someone is in close proximity to an emitter and there’s little active or passive mixing. CO2 will generally diffuse more evenly throughout a space than aerosols.
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Ultimately the question is how actionable the output is. What’s the sensitivity and specificity of the number in detecting high risk of infection scenarios. There will be scenarios where CO2 is low and risk of infection is high, and those where CO2 is high but risk of infection is low.
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And source control hoods such as this one tested by @simonjoosten.bsky.social
pubmed.ncbi.nlm.nih.gov/35156259/
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That’s close to the single pass efficiency of the 3M Filtrete 1900s in those configurations with a total high filter surface area that result in low face velocities.
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50-80 USD is the original manufacturing cost from Chinese suppliers.
ts-hvac.en.made-in-china.com/product/VZkE...
kanionco.en.made-in-china.com/product/CdxJ...
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You can also get a 15% CADR boost using the 3rd Party Pureburg filter and simply removing the layer of carbon bsky.app/profile/clea...
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The Midea is found in Europe, the Lago is found in the U.S.
We opened up both of them (and the AP003) and found the model KJ-350G-S1 stamped across all three. Same model with a license to be rebranded and sold.
Danny shared how it works starting at this point of the video youtu.be/HwrAv4Vah0s?...
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Great insights. Should be noted that if you remove the carbon layer from the Pureburg (easy to do) you actually get a CADR boost above the original OEM filter with the HEPA component being the same thickness. bsky.app/profile/clea...
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The folks at @housefresh.bsky.social tested the UK Midea version and apparently found it to be quieter at each fan speed relative to the Taotronics device, so it’s possible they may have slight manufacturing differences.
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They are likely the same generic device white labeled under many different brands, but not aware of any specific testing of the Lorell 420 device.
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But assessing actual individual risk isn’t possible. CO2 can still be valuable though in helping determine where there is likely “addressable” elevated risk.
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Yes. A high CO2 can tell you there’s room for improvement with ventilation (engineering perspective i.e. modifiable environment factors) or reducing occupancy (public health perspective i.e. numbers of potential emitters and susceptibles that could continue chains of transmission).
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This specifies the conditions under which that risk was calculated (even then it would be challenging to read this chart reliably due to the additional variables of emission rate which can vary by orders of magnitude due to variables such as emitter’s viral load, vocalisation etc)
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There would be at least a couple of considerations.
1. Relative risk from poor ventilation (Need to estimate ventilation which is not straightforward)
2. Relative risk from modified viability (still too early to verify significance)
Goal is deriving some semblance of actionable data.
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Who did this for you?
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Unfortunately you won’t be able to calculate risk of transmission as its function is dependent on variables you have no ability to assess (emission rate, distance to emitter, airflow direction, etc). Best you can do is calculate relative risk against another scenario with adjusted variables.
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4/ To learn more, watch this excellent presentation "Equivalent Clean Airflow and Air Cleaners - key to sustainable IAQ" from Nov 18 2024: event.webcasts.com/starthere.js...
Bahnfleth describes the history at 39 minutes.
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They are great. Even at lowest fan speed noise can be problematic however in quiet classrooms. Sub 40dBA is really the minimum and with an acceptable noise characteristic.
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You would need to be running them on the lowest speed at 153CFM each unless it was a very noisy classroom and you could run them at a higher speed.
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While the wall mounting is useful, the CADR achieved for a given noise level is fairly low meaning you would need a large number in a classroom to deliver meaningful risk reduction.
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We published a video that looked at a few different versions of this air purifier as they are all based on the Midea KJ350G-S1 youtu.be/HwrAv4Vah0s?...
If you search for this name you can find all the other filters that fit.
Thanks @cleanairstars.com for originally sharing it was white-labelled.
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Interestingly many of these performance venues have always had good ventilation as part of their initial design.