air purifier buying guide

	A	B	P
1	Other questions? Feedback? Email rachel@CleanAirCommunications.com	Intro: This is written with U.S. currency (for now). This list from left to right is mostly in order of Clean Air Delivery Rate with our favorite reputeable purifiers only, and only devices that are 45 decibels or quieter (or can be set to 45 dB and still have a decent CADR). You can sort in order of cost or Air Changes per Hour. Ionizer/UV/ozone isn't included because none of these purifiers contain that option. If you're shopping for a loud environment like a gym or restaurant, you can get by with a louder setting (and greater CADR!) If the purifier you're seeing on Amazon isn't on here, don't get it. If the purifier you already own isn't on here, then you can email us and we'll let you know the stats! Keeping people's exhaled germs off of other people 101: clean air delivery rate (CADR, pronounced kay-dar or C-A-D-R, or, or getting nervous you'll mess up and saying all four words each time, however you want to say it!) is listed as cubic feet per minute (cfm)--1 cfm would be mean a 1' x 1' x 1' box of dirty air is cleaned per minute. The higher the cfm the better (faster) your clean air delivery rate is. When you're trying to quickly and continously clean a space where people are hanging out and trying to not get each other sick, fast is the goal. If you can leave a purifier in a room and stay masked or leave and come back, then a really high quality HEPA filter is fine even if it's moving the air slowly. But the goal of this buying guide is assuming people want quick air cleaning before they breathe in the bad stuff. Aim for 30-50 cubic feet per minute of cleaned air PER PERSON. So for an average-sized classroom, the volume is 7,000 cubic feet. If there are 25 people in the class and you need an air-cleaning rate of 40 cubic feet per minute, that means you need to filter about 1/7 of the air per minute or 1,000 cubic feet each minute. If you're looking at the recommendation of 6-12 air changes per hour, the formula for that is 60/room volume * clean air delivery. Example: 30'x30' classroom (ceiling height doesn't matter for our purposes so we'll say 8 ft.) 30308 = 7,200 (room volume) 7,200 x ? = 6 ACH <--This tells us we need at least 1,200 cfm to achieve 6 air changes per hour. But remember to subtract 50-150 cfm for natural air leakage OR 400 cfm for an HVAC system with a MERV 13 filter where the fan stays constantly on. So let's assume this classroom in the example has HVAC and the school agrees to leave the fan running instead of on "auto." We know we need 1,200 cfm with the air changes per hour guide and we need 1,000 cfm with the per-person guide. 1,200-400 =800 cfm. So we need to add up enough air purifiers with high enough CADR to get to 800 cfm. We can do that with 2 Luggable XLs and most commercial HEPA purifiers like Levoit or Medify or Coway. Just add up any of the purifiers you're thinking of getting using the CADR column (column C) and make sure you get to the number that covers either your room occupancy (preferred method for crowded spaces) or room volume (preferred method for lower occupancy like homes and some offices). Another purifier need is portable/personal where you "hog" the clean air yourself. Like at the dentist, in a waiting room, or on an airplane/train. For that, we don't consider room-cleaning power/CADR, but rather if the "laminar airflow" is sufficient for giving you a clean enough stream of air to help protect you from the uncleaned air around you (like when you don't have control of a space or if it's unknown.) NOTES: Where possible, the CADR is specific to virus control, which is calculated: 0.3(Dust CADR) x 0.3(Smoke CADR) x 0.4(Pollen CADR); if there isn't an asterisk, then it means we just used smoke CADR	tl;dr -- Go to "favorites" tab, start at the top (it's in order of highest clean air delivery rate to lowest) and stop when you get to one you can afford :) Add more units to your collection as budget permits.

2
3	Other helpful resources: * Portable Air Filters (CleanAirStars.com/filters) -- mega database * So ya wanna buy a portable HEPA air filter? (by IACA)
4	* purifier sizing guide with formulas (CleanAirKits.com)
5
6
7