Reference charts
Quick answer
Dense tables, each built around one published standard or one piece of arithmetic you can repeat. There are 10 pages in this section.
MOOKA Air Purifiers for Home Room up to 1076ft2, True HEPA Filter, B-D02L
A machine with a published specification, which is what makes the arithmetic on these pages applicable to it rather than to a coverage claim with no rate behind it.
Prices and specifications change, so check the listing before buying.
Every page in this section
- Chart
How long to remove airborne particles at different air changes per hour
Clearance time to remove 90 and 99 percent of airborne particles by air change rate. Formula for calculating purifier effectiveness.
- Chart
Ideal indoor humidity levels and window condensation limits by outdoor temperature
Target 30 to 50 percent relative humidity indoors. Safe maximum humidity by outdoor temperature to avoid window condensation and mold growth.
- Chart
Indoor air particle sizes: what air purifiers actually remove
A size reference for indoor particles: pollen, dust mites, smoke, mold spores, bacteria, and pet dander in microns. HEPA filtration effectiveness at different particle sizes.
- Chart
Match CADR to room size: coverage at 2, 4.5, and 6 air changes per hour
Calculate the floor area a purifier covers by CADR and air change rate. Eight-foot ceiling reference for bedrooms, living rooms, and whole-home sizing.
- Chart
MERV 1 to 16 filters: particle capture by size and typical use
ASHRAE 52.2 MERV ratings explained: capture efficiency for large, medium, and small particles. Choose MERV for allergies, furnace filters, and air quality needs.
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PM2.5 concentration levels, corresponding AQI, and what your monitor reading means
Interpret PM2.5 measurements: air quality at different micrograms per cubic meter, health impact, and when to run an air purifier.
- Chart
Real air purifier filter costs over five years: maintenance expense compared to unit price
Filter replacement costs and 5-year total cost of ownership for 16 air purifier models. Find the hidden cost of filter maintenance.
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True HEPA vs HEPA-type: H13 and H14 standards, and what "99.9 percent" claims miss
HEPA definition of 99.97 percent at 0.3 microns. EN 1822 H13 and H14 certification. Why HEPA-type is meaningless without a standard.
- Chart
Understanding the US AQI: categories, PM2.5 concentrations, and indoor action levels
Complete AQI index breakdown: air quality categories, PM2.5 concentration ranges, health impact, and when to run an air purifier indoors.
- Chart
Which air purifiers emit ozone: ionizers, plasma, ozone generators, and UV-C
Ozone health risks and which technologies produce it. CARB certification status. How to identify if a purifier emits ozone.
Equipment that comes up most often here
- Filterbuy
Filterbuy 20x20x1 Air Filter MERV 8 Dust & Allergy Defense (4-Pack)
$29.96 Check pricePrices change often - Aerostar
Aerostar Air Filter 20x20x1 MERV 8 AC Filter, HVAC, Furnace Filter, 6 Pack
$32.45 Check pricePrices change often
Common questions
How is any of this researched?
From published test standards, published manufacturer specifications and owner reports, plus arithmetic that is printed on the page so you can check it. Nothing on this site was tested in a chamber by us, and no price, image or product identifier here was invented or estimated.
Do these pages recommend ionizers or ozone devices?
No. Ozone generators are harmful in occupied rooms and are never recommended here at any price, which is why California CARB regulates ozone emissions from indoor air cleaning devices. Where an ordinary machine has an ionizing or plasma mode, these pages say it can be switched off and that the filtration is doing the work.
Where should I start if I am new to this?
With the sizing calculator, because the airflow a room needs narrows the field faster than any list of machines. Once you know the number, most of the marketing on a box stops mattering, and the remaining decision is usually about noise and what the filters cost each year.
Are the prices current?
They are rebuilt from live product listings each time the site is published, so they match what things cost when these pages were last built. Prices move often, so check the listing before buying and treat every total here as a budget rather than a quote.