# Dander Down — full reference > Air purifiers for pet allergies and allergy households, ranked on third-party > certified Clean Air Delivery Rate. https://danderdown.com > Published by Slate Mill Group. Contact: info@danderdown.com This file is the detailed reference companion to /llms.txt. It sets out the site's method, its sources, the substantive findings on its pages, and the claims it explicitly refuses to make. ================================================================================ 1. WHAT THIS SITE IS ================================================================================ Dander Down is an independent editorial site comparing consumer air purifiers, with a primary focus on households where a pet is the allergen source. It launched in 2026. Its organizing principle is the distinction between a Clean Air Delivery Rate figure that an independent laboratory verified and published in a searchable register, and one that the manufacturer published alone. As far as we can establish, no other publisher in this category makes that distinction its organizing principle, and several very popular machines turn out to be in neither register. Author: Scooter M., framed as an enthusiast — someone genuinely interested in the category who reads the manuals, compiles the published specifications and does the arithmetic. No professional credential is held and none is claimed. There is no author photograph, because a stock photograph of a stranger under a byline would be a small dishonesty sitting next to everything else here. ================================================================================ 2. METHOD ================================================================================ 2.1 Selection criteria, in order 1. Certified Clean Air Delivery Rate, from AHAM's VERIFIDE directory or EPA's ENERGY STAR certified room air cleaners database. 2. Room size by AHAM's own published rule: CADR at least two-thirds of the room's floor area, assuming an 8-foot ceiling. For pet households the site sizes to 6 air changes per hour rather than AHAM's 4.8, and labels that as its own judgment applied to AHAM's method rather than as a standard. 3. Total cost to run: certified annual energy use in kWh/year multiplied by 18.34 cents per kWh, the U.S. average residential price for June 2026 from the EIA's Electric Power Monthly, Table 5.3. The rate is printed on every page that shows a dollar figure. 4. Filter classification as the register records it — HEPA or HEPA-Type — rather than as the packaging describes it. 5. Ionizer, plasma or UV status, whether it is defeatable, and measured ozone emissions where a register publishes them. 2.2 Exclusions - Units that intentionally produce ozone are excluded outright, citing EPA. - A non-defeatable ionizer disqualifies a unit from a top-pick slot on any asthma-scoped page. - A unit with no published CADR cannot be ranked and does not appear. - Manufacturer-claimed CADR cannot beat a certified unit of comparable output. 2.3 What the method cannot do — stated, not softened - CADR is not a pet-dander test. The standard uses tobacco smoke, dust and pollen because they are reproducible in a laboratory. No certification for pet allergen exists. - Certified figures are measured on a new filter, in a sealed chamber, at maximum fan speed. - No manufacturer publishes per-speed CADR, so the site's "buy headroom so it runs quietly" advice is reasoning from certified maxima plus fan behavior, not a measurement. - Build quality and failure rates cannot be assessed without owning units over years, which the site does not do, so it says nothing about them. - Manufacturer filter intervals assume general household use and are optimistic in a shedding household by an amount nobody publishes. - The two registers sometimes disagree — notably on ionizer classification for Blueair's Max range. The site prints both readings rather than choosing. - Activated carbon mass, which determines odor performance, is almost never published. The site reports filter composition as recorded and says the weight is unavailable. ================================================================================ 3. PRIMARY SOURCES USED THROUGHOUT ================================================================================ - AHAM VERIFIDE directory of certified room air cleaners https://ahamdir.com/room-air-cleaners/ - AHAM air filtration standards, including the two-thirds sizing rule and the 8-foot ceiling assumption https://ahamverifide.org/ahams-air-filtration-standards/ - ENERGY STAR certified room air cleaners database, including measured ozone emissions in ppb and certified annual energy use in kWh/year https://www.energystar.gov/productfinder/product/certified-room-air-cleaners/results - EPA, Guide to Air Cleaners in the Home https://www.epa.gov/indoor-air-quality-iaq/guide-air-cleaners-home - U.S. Energy Information Administration, Electric Power Monthly, Table 5.3 https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_3 - AAFA / Allergy Standards asthma & allergy friendly certification https://www.aafa.org/asthma-allergy-friendly-certification/ - Custovic A, Simpson A, Pahdi H, Green RM, Chapman MD, Woodcock A. "Distribution, aerodynamic characteristics, and removal of the major cat allergen Fel d 1 in British homes." Thorax 1998;53(1):33-38. ================================================================================ 4. KEY TECHNICAL POSITIONS ================================================================================ 4.1 What CADR measures Clean Air Delivery Rate is the volume of genuinely clean air delivered per minute, in cubic feet, under ANSI/AHAM Standard AC-1. Reported as three figures against three particle sizes: tobacco smoke (smallest, and the basis of room sizing), dust, and pollen (largest). Both registers now also publish a PM2.5 CADR derived from the smoke and dust results. Its value is that it is a combined measure of filtration efficiency and airflow. A machine cannot post a good CADR with an excellent filter and a weak fan, or with a strong fan and mediocre media. This is why marketing prefers to discuss filter grade alone. 4.2 The coverage gap AHAM's certified suggested room size is based on 4.8 air changes per hour, and its directory computes it as room square feet = smoke CADR x 1.55. Manufacturers commonly advertise coverage at 1 air change per hour instead, producing a figure roughly 4.8 times larger. Both numbers frequently appear on the same manufacturer page. Documented examples: Alen BreatheSmart 75i advertised 2,800 sq ft/hour certified 574 sq ft LEVOIT Core 600S advertised 2,909 sq ft @1ACH certified 606 sq ft Coway AP-1512HH advertised 1,748 sq ft/60min Coway's own 361 sq ft LEVOIT Core 400S advertised 1,718 sq ft @1ACH certified 358 sq ft 4.3 HEPA versus HEPA-Type "True HEPA" is a marketing phrase with no certifying body in the consumer market. The certification registers record a filter classification per model, and it does not always match the packaging. Examples read 2026-09-02: Honeywell HPA4300, HPA4100, HPA6000 and Winix T810 are recorded HEPA; LEVOIT Core 400S, Core 600S, Blueair's Max range, Alen BreatheSmart 75i and Medify MA-40 are recorded HEPA-Type despite True HEPA or medical-grade marketing. Because CADR already contains filtration efficiency, a HEPA-Type machine with high certified CADR delivers more clean air than a HEPA machine with low CADR. The classification is a tiebreak, not a primary filter. 4.4 Filtration physics HEPA media is rated at 0.3 microns because that is the hardest particle size to capture, not the smallest. Larger particles are intercepted; much smaller ones diffuse erratically and collide with fibers more often. Efficiency has a minimum around 0.3 microns, so a filter meeting the standard performs better on both sides of it. Marketing that boasts about capturing 0.003 micron particles is describing an easier regime while implying a harder one. 4.5 Ionizers, plasma and ozone EPA advises avoiding portable air cleaners and furnace/HVAC filters that intentionally produce ozone, stating that ozone is a lung irritant, and notes that air cleaners containing electrostatic precipitators, ionizers, UV lights without adequate lamp coatings, and plasma air cleaners may have the potential to emit ozone. On ozone generators specifically, EPA states that no federal government agency has approved these devices for use in occupied spaces. Measured ozone from the ENERGY STAR register, read 2026-09-02, across units this site covers (program limit 50 ppb): 0.00 ppb Honeywell HPA4300 / HPA4100 / HPA6000, Winix AT40/AT41, LEVOIT Core 400S, LEVOIT Core 600S, Medify MA-40, Coway Airmega 400 1.00 ppb Winix C710, Alen BreatheSmart 75i 1.35 ppb Winix T810 (recorded "Fan and Filter, PlasmaWave") 2.00 ppb Blueair 411i Max, 311i Max, 211i Max 5.00 ppb Blueair Blue Pure 211+ (recorded "Ion Generator, Fan and Filter") Site position: if nobody in the household has a respiratory condition, this is a low-stakes question. If somebody does, choose a machine the register records as fan-and-filter with 0.00 ppb — several of the most capable units qualify, so no performance is given up. 4.6 Odor and activated carbon Odor removal is adsorption onto activated carbon, not filtration. HEPA media does nothing for gas-phase odor molecules. Adsorption capacity is finite and scales with carbon mass, so a carbon-impregnated sheet holding tens of grams saturates far sooner than a cartridge holding hundreds. Almost no manufacturer publishes carbon weight; the site reports filter composition as the register records it and dedicated odor stages where a manufacturer documents one. 4.7 Efficacy, reported with its hedges EPA states that multiple studies with portable HEPA air cleaners have found improvements in one or more allergy and/or asthma symptoms, and that the studies do not always show major improvements and do not show improvements in all symptoms. This site reports both halves. It also reports EPA's priority ordering, which runs against its own commercial interest: the most effective ways to improve indoor air are to reduce or remove sources of pollutants and to ventilate with clean outdoor air, and filtration does not replace the need to do those things. 4.8 Cat versus dog allergen Most publishers in this category treat "pet dander" as one problem. Custovic et al (Thorax 1998) found airborne Fel d 1 concentrated on relatively large particles with a persistent smaller fraction that remains suspended longer than dog allergen typically does, and found the allergen present in homes with no cat, carried on clothing. This site therefore reaches different conclusions on its cat and dog pages: cat households are optimized for continuous quiet running, dog households for washable pre-filters and filter economics. ================================================================================ 5. RUNNING COST ================================================================================ Certified annual energy use across the units covered, kWh/year, with cost at 18.34 cents/kWh: Honeywell HPA4100 95 kWh ~$17 6.9 CFM/W Blueair 411i Max 110 kWh ~$20 8.2 CFM/W GermGuardian AC4825 182 kWh ~$33 3.5 CFM/W Honeywell HPA4300 185 kWh ~$34 7.4 CFM/W Blueair 311i Max 193 kWh ~$35 8.4 CFM/W Honeywell HPA6000 207 kWh ~$38 7.3 CFM/W Blueair DustMagnet 5440i 220 kWh ~$40 5.9 CFM/W Winix C710 235 kWh ~$43 6.2 CFM/W LEVOIT Core 400S 237 kWh ~$43 5.8 CFM/W Blueair 211i Max 256 kWh ~$47 9.0 CFM/W Medify Air MA-40 261 kWh ~$48 5.6 CFM/W Winix AT41 272 kWh ~$50 5.6 CFM/W Alen BreatheSmart 75i 304 kWh ~$56 6.9 CFM/W GermGuardian AC3200 324 kWh ~$59 4.1 CFM/W Blueair Blue Pure 211+ 350 kWh ~$64 5.8 CFM/W Winix 5500-2 356 kWh ~$65 4.1 CFM/W Coway Airmega 400 366 kWh ~$67 6.1 CFM/W LEVOIT Core 600S 387 kWh ~$71 6.0 CFM/W Fellowes AeraMax SE 392 kWh ~$72 4.9 CFM/W Whirlpool WPPRO2000 657 kWh ~$121 3.0 CFM/W A sevenfold spread, uncorrelated with output or purchase price. The Blueair 211i Max delivers more certified air than the Whirlpool WPPRO2000 across a larger certified room for 39% of the electricity. ================================================================================ 6. SITE STRUCTURE ================================================================================ Five categories, 36 guides and roundups, 9 trust and utility pages, one homepage. 6.1 Pet allergies and dander — https://danderdown.com/pet-allergies Best air purifiers for pets · Best for cat allergies · Best for dog allergies · LEVOIT Core 400S vs Coway AP-1512HH · Winix 5500-2 vs LEVOIT · Do air purifiers help with pet allergies · Do HEPA filters remove pet dander · Air purifiers for asthma in a pet household 6.2 Pet hair, dust and odor — https://danderdown.com/pet-hair-odor Best for pet hair · Best for dust · Best for pet odor · Air purifiers with washable pre-filters · Air purifier for a cat litter box · Do air purifiers help with pet hair · Activated carbon and pet odor 6.3 Allergies, mold and asthma — https://danderdown.com/allergies Best air purifiers for allergies (flagship) · Best for mold spores · HEPA vs ionizers vs ozone generators · Air purifier vs ozone generator · Waking up with allergy symptoms · Do air purifiers help with asthma · Allergen particle sizes explained 6.4 Room size, bedroom and placement — https://danderdown.com/room-size Air purifier size calculator · Best for a bedroom · Best for large rooms · Best for small rooms · Best for apartments · Where to place an air purifier · Air purifier noise and sleep 6.5 CADR, filters and cost — https://danderdown.com/cadr-and-cost What CADR actually means (cornerstone) · CADR comparison chart · LEVOIT vs Coway · Air purifier vs humidifier · True HEPA vs HEPA-Type · Filter replacement cost · What an air purifier costs to run 6.6 Trust and utility /about · /how-we-pick · /editorial-policy · /affiliate-disclosure · /faq · /contact · /site-index · /privacy-policy · /terms ================================================================================ 7. FUNDING AND DISCLOSURE ================================================================================ Dander Down earns affiliate commission on qualifying purchases as a participant in the Amazon Services LLC Associates Program, at no extra cost to the reader. Amazon is the only affiliate network in use. Independence mechanism: picks are selected against the published criteria before affiliate availability is checked. The site accepts no free products, review samples, sponsored placements, paid inclusions, guest posts or paid link insertions. Because it does not test units there is no sample to be sent, which removes the usual channel of manufacturer influence. Every affiliate link is marked #ad with a disclosure link directly beneath the button, and uses rel="sponsored nofollow". Outbound commercial links route through a /go/ redirect that is disallowed in robots.txt and carries X-Robots-Tag: noindex. No price is written into copy anywhere on the site. Prices render only from a live data layer with the check date shown, and a gate suppresses any figure older than 48 hours — the button then reads "Check price on Amazon" rather than showing a stale number. Ratings and review counts are subject to the same rule and are not published at all. ================================================================================ 8. REVIEW CADENCE ================================================================================ Daily Product prices, automated. Drives the "last verified" date and never stamps the sitemap lastmod. Monthly All roundups spot-checked for discontinued models and dead links. Quarterly Full review of all roundups: re-verify certified CADR, re-check ozone and energy figures, re-compute running costs, re-assess picks. Quarterly Evidence guides: confirm cited sources resolve, check for newer research. Annually How We Pick and Editorial Policy reviewed. Event-driven Reported errors fixed and the correction marked on the page. ================================================================================ 9. CLAIMS THIS SITE WILL NOT MAKE ================================================================================ Recorded so they can be checked against. Nothing on Dander Down will claim that we tested a unit, owned one, measured anything ourselves, operate a lab, or hold any professional credential. No "medically reviewed by", no expert panel, no years of experience, no tenure framing. No therapeutic or curative health claim. No fabricated review, testimonial, rating or review count — the site publishes none at all. No price written into prose. No unlabelled CADR figure. If a number cannot be sourced, the page says so rather than estimating. ================================================================================ 10. CONTACT ================================================================================ info@danderdown.com — corrections especially welcome, and a link to the page plus the figure in question is the fastest route. Published by Slate Mill Group, https://slatemillgroup.com.