CADR Ratings Guide For Air Purifiers

Article Contents

What is the Clean Air Delivery Rate?

The Clean Air Delivery Rate, or CADR for short, of an air purifier is a numerical value assigned to an air purifier based on independent tests performed for the Association of Home Appliance Manufacturers (or AHAM). AHAM has been measuring the CADRs of air cleaners since the 1980s.

According to the online encyclopedia Wikipedia, the CADR definition is an indication of the volume of filtered air delivered by a portable air purifier. It goes on to say that CADR describes how well the cleaner reduces tobacco smoke, pollen and dust. In other words, the CADR is an attempt to provide a uniform, objective standard by which potential buyers can easily evaluate the effectiveness of an air cleaner.

Given the potentially bewildering variety of air purifiers available in the marketplace, such a standard is highly desirable. AHAM's own literature on CADR also emphasizes that CADR ratings are valid "regardless of the particle removal technology utilized," so it does not matter whether the purifier uses, for example, a HEPA filter or an ionizer. CADR measures only the end results.

Note that CADR testing (PDF) is applied only to portable air purifiers, not to large whole-house purifiers, which require a different method to measure their effectiveness.

How is CADR Determined?

An air cleaner is given a CADR through a relatively easy to understand process, which is called the ANSI/AHAM AC-1 standard which measures CADR requirements:

The purifier is placed in a testing chamber of 1008 cubic feet.
Before the purifier is activated, the amount of contaminants in the room is measured.
The purifier is activated for a period of twenty minutes, during which time the amount of contaminants is periodically re-evaluated.
Finally, the reduction in contaminants is compared to their natural rate of decay.

When this test is over, testers proceed to give the unit its rating. The United States Environmental Protection Agency explains the number in the following way:

"The CADR is a measure of a portable air cleaner’s delivery of contaminant-free air, expressed in cubic feet per minute. For example, if an air cleaner has a CADR of 250 for dust particles, it may reduce dust particle levels to the same concentration as would be achieved by adding 250 cubic feet of clean air each minute." - Environmental Protection Agency

AHAM's Three CADR Ratings

There are three CADR ratings given on the AHAM seal. These represent the air cleaners' effectiveness against three different common indoor air pollutants: tobacco smoke, pollen, and dust. AHAM recommends a "two thirds" rule when it comes to the first rating: "You'll always want a unit with a tobacco smoke CADR at least 2/3 your room's area."

Highest Possible CADR Ratings

Due to the fact that the tests always use the same room size, there is an upper limit to meaningful CADR ratings:

Tobacco Smoke 10 to 450 CADR
Dust 10 to 400 CADR
Pollen 25 to 450 CADR

How Accurate and Useful are CADR Ratings?

As indicated above, CADR testing has a history of nearly 30 years, and in that time, its use has spread. Reputable organizations beyond the air purification industry have adopted CADR, including the Environmental Protection Agency, the Federal Trade Commission, and the independent watchdog organization Consumers Union.

There is no reason to believe that CADRs are not effective, within limits. Nonetheless, as always, a certain measure of caution is advisable.

Limits of CADR Ratings

The limits of CADRs are spelled out well by Ed Sherbenou, an air purifier expert who runs the website Air Purifier Power. He does not deny the usefulness of CADR ratings, but he also claims that "it's what CADRs don't say" that can mislead people shopping for effective purifiers.

Small Particle Filtration Effectiveness Not Shown - CADR numbers do not adequately inform customers of a purifier's ability to filter out very small particles. Yet these are the most numerous, and often the most dangerous, pollutants. Looking at an air cleaner's Clean Air Delivery Rate, you cannot tell how effective it is in dealing specifically with these tiniest bits of matter. Many air purifiers eliminate larger particles very well but are almost completely incapable of removing smaller ones from circulation.

Gas Filtration Not Measured - The test does absolutely nothing to measure a purifier's ability to rid the air of gaseous pollutants, such as dangerous Volatile Organic Compounds. The three CADR numbers all refer to particulate pollution only, which is very different from gaseous pollution. Air purifiers vary wildly in their ability to deal with the latter. Because cleaning gas pollution requires different mechanisms from cleaning solid particle pollution, a purifier's effectiveness at reducing gas is completely unrelated to its effectiveness at reducing particles.

Doesn't Show Decline in Effectiveness Over Time - Because the test is so short, it does not account for the fact that some purifiers will decline in effectiveness over time.

Purifiers Run At Their Highest Settings - Fourth, in the ANSI/AHAM AC-1 test, purifiers are always run on their highest setting. But users will often use lower settings to reduce noise, and this can drastically reduce the efficiency of an air cleaner.

In the end, according to Sherbenou, CADR numbers are useful, but only to a certain extent:

"The cheaper the purifier, the more important the AHAM air delivery rate becomes, relative only to other units in its price class." - Ed Sherbenou, Air Purifier Power

Though Clean Air Deliver Ratings can be found for a large number of popular brands, many of the most well-respected companies in the air purification field do not give CADRs to their purifiers. This should in no way bias potential customers against them.

Conclusion

CADR is one tool to measure the effectiveness of air purifiers. It should neither be ignored, nor considered the only important factor in determining the value of an air cleaner. Instead, potential customers should check for CADR numbers as one of a number of things to keep in mind, along with other factors such as long-term durability and the ability to filter out gasses and odors.
CADR only measures tobacco smoke, dust, and pollen
CADR formulas only measure the ability to remove 80% of tobacco smoke assuming one air exchange per hour
CADR does not measure the effectiveness of filtering the size of particles

Clean Air Delivery Rate of Air Purifiers
(Numbers Provided by AHAM - Updated July 2011)

Score ranges shown below. A higher rating equates to a greater ability to filter that particular type of pollutant. Please note that there are many air purifier models that are not rated by this system.

Tobacco Smoke 10 to 450 CADR
Dust 10 to 400 CADR
Pollen 25 to 450 CADR

Manufacturer	Brand	Model	Dust CADR	Tobacco Smoke CADR	Pollen CADR	Room Size (Sq Ft)	Meets Ozone Limits
3M Company	Filtrete	FAP00	51	67	58	104	Yes
3M Company	Filtrete	FAP01	86	72	97	110	Yes
3M Company	Filtrete	FAP02	137	112	153	170	Yes
3M Company	Filtrete	FAP02-LS	137	112	153	170	Yes
3M Company	Filtrete	FAP02-LY	137	112	153	170	Yes
3M Company	Filtrete	FAP02-RC	137	112	153	170	Yes
3M Company	Filtrete	FAP02-RS	128	103	149	160	Yes
3M Company	Filtrete	FAP03-LS	306	241	332	370	Yes
3M Company	Filtrete	FAP03-LY	306	241	332	370	Yes
3M Company	Filtrete	FAP03-RC	306	241	332	370	Yes
3M Company	Filtrete	FAP03-RS	274	224	312	350	Yes
3M Company	Filtrete	FAP04-RS-2	110	110	128	171
Access Business Group	Atmosphere Air Purifier	101076	250	250	250	390	Yes
Access Business Group	Atmosphere Air Purifier	102858	250	250	250	390	Yes
Access Business Group	Atmosphere Air Purifier	101076CH	260	250	261	390	Yes
Airgle Corporation	Airgle	Airgle 750	>400	>450	>450	698
Blueair, Inc.	Blueair	103	120	100	110	155
Blueair, Inc.	Blueair	203	115	115	115	175	Yes
Blueair, Inc.	Blueair	303	145	145	145	225
Blueair, Inc.	Blueair	403	240	240	240	370	Yes
Blueair, Inc.	Blueair	503	375	375	375	580	Yes
Blueair, Inc.	Blueair	603	>400	415	>450	640	Yes
Blueair, Inc.	Blueair	215B	115	115	115	175	Yes
Blueair, Inc.	Blueair	270E	135	135	135	210	Yes
Blueair, Inc.	Blueair	450E	240	240	240	370	Yes
Blueair, Inc.	Blueair	455EB	240	240	240	370	Yes
Blueair, Inc.	Blueair	510B	377	388	378	620	Yes
Blueair, Inc.	Blueair	550E	390	390	390	605	Yes
Blueair, Inc.	Blueair	555EB	390	390	390	605	Yes
Blueair, Inc.	Blueair	610B	>400	380	>450	590	Yes
Blueair, Inc.	Blueair	650E	>400	>450	>450	698	Yes
Blueair, Inc.	Blueair	ECO10	195	190	200	298	Yes
Blueair, Inc.	Blueair	MD Pro	240	240	240	370	Yes
Brookstone	Pure Ion Pro	630285	234	188	347	292	Yes
Chung Pung Co. Ltd	Mugu	CAP-G4018	425	394	434	610
Daikin AC	Daikin	MC75KSU	200	172	210	267	Yes
Electrolux Home Care Products NA	Electrolux	EL490A	212	210	229	326
Electrolux Home Care Products NA	Electrolux	EL491A	212	210	229	326
Electrolux Home Care Products NA	Electrolux	EL500A	262	261	253	405
Electrolux Home Care Products NA	Electrolux	EL500AX	262	261	253	405
Electrolux Home Care Products NA	Electrolux	EL500AZ	262	261	253	405
GE Consumer & Industrial	General Electric	AFHC08AM	110	88	122	136
GE Consumer & Industrial	General Electric	AFHC09AM	110	88	122	136
GE Consumer & Industrial	General Electric	AFHC21AM	229	212	239	329
GE Consumer & Industrial	General Electric	AFHC23AM	229	212	239	329
GE Consumer & Industrial	General Electric	AFHC32AM	335	322	325	499
GE Consumer & Industrial	General Electric	AFHC33AM	335	322	325	499
Gree Electric Appliances, Inc.	Gree	GCF280CANA	160	140	180	220
Gree Electric Appliances, Inc.	Soleusair	AH1-CC-01	160	140	180	220
Haier America	Haier	HAPE200	202	130	249	201
Haier America	Haier	HAPE300	233	170	232	264
Haier America	Haier	HAPM100	102	69	119	107
Headwaters Inc.	Brookstone	561274	225	176	237	273	Yes
Headwaters Inc.	FilterStream	A550	225	176	237	273	Yes
Headwaters Inc.	FilterStream	A600	257	160	256	248
Headwaters Inc.	FilterStream	A700	285	260	275	403
Headwaters Inc.	FilterStream	A710	285	260	275	403
HoMedics, Inc.	HoMedics	AR-10	91	75	99	116
HoMedics, Inc.	HoMedics	AR-20	126	117	123	181
Kaz, Inc.	Honeywell	10590	91	91	91	140	Yes
Kaz, Inc.	Honeywell	16200	44	53	58	80	Yes
Kaz, Inc.	Honeywell	17000	130	130	130	200	Yes
Kaz, Inc.	Honeywell	17005	130	130	130	200	Yes
Kaz, Inc.	Honeywell	18155	132	127	135	197	Yes
Kaz, Inc.	Honeywell	50100	100	100	100	150	Yes
Kaz, Inc.	Honeywell	50101	100	100	100	150	Yes
Kaz, Inc.	Honeywell	50150	150	150	150	235	Yes
Kaz, Inc.	Honeywell	50200	200	200	200	304	Yes
Kaz, Inc.	Honeywell	50250	250	250	250	390	Yes
Kaz, Inc.	Honeywell	16200C	44	53	58	80	Yes
Kaz, Inc.	Honeywell	17000-N	130	130	130	200	Yes
Kaz, Inc.	Honeywell	17000-S	130	130	130	200	Yes
Kaz, Inc.	Honeywell	17000-TGT	130	130	130	200	Yes
Kaz, Inc.	Honeywell	17005-N	130	130	130	200	Yes
Kaz, Inc.	Honeywell	17007-HD	130	130	130	200	Yes
Kaz, Inc.	Honeywell	50100-N	100	100	100	150	Yes
Kaz, Inc.	Honeywell	50150-N	150	150	150	235	Yes
Kaz, Inc.	Honeywell	50200-N	200	200	200	304	Yes
Kaz, Inc.	Honeywell	50250-N	250	250	250	390	Yes
Kaz, Inc.	Honeywell	50250-S	250	250	250	390	Yes
Kaz, Inc.	Honeywell	50255-HD	250	250	250	390	Yes
Kaz, Inc.	Honeywell	HAW-501	36	24	47	37	Yes
Kaz, Inc.	Honeywell	HFD-010	35	40	55	62	Yes
Kaz, Inc.	Honeywell	HFD-010C	35	40	55	62	Yes
Kaz, Inc.	Honeywell	HFD-015	35	40	55	62	Yes
Kaz, Inc.	Honeywell	HFD-015C	35	40	55	62	Yes
Kaz, Inc.	Honeywell	HFD-110	69	80	88	124	Yes
Kaz, Inc.	Honeywell	HFD-110C	69	80	88	124	Yes
Kaz, Inc.	Honeywell	HFD-112	69	80	88	124	Yes
Kaz, Inc.	Honeywell	HFD-116C	69	80	88	124	Yes
Kaz, Inc.	Honeywell	HFD-120-Q	100	110	132	170	Yes
Kaz, Inc.	Honeywell	HFD-120QC	100	110	132	170	Yes
Kaz, Inc.	Honeywell	HFD-122C	100	110	132	170	Yes
Kaz, Inc.	Honeywell	HFD-122-TGT	100	110	132	170	Yes
Kaz, Inc.	Honeywell	HFD-123-HD	100	110	132	170	Yes
Kaz, Inc.	Honeywell	HFD-130	100	110	130	169	Yes
Kaz, Inc.	Honeywell	HFD-130C	100	110	130	169	Yes
Kaz, Inc.	Honeywell	HFD-135	98	98	98	150	Yes
Kaz, Inc.	Honeywell	HFD-137	98	98	98	150	Yes
Kaz, Inc.	Honeywell	HFD-139	98	98	98	150	Yes
Kaz, Inc.	Honeywell	HHT-011	55	55	65	85	Yes
Kaz, Inc.	Honeywell	HHT-011C	55	55	65	85	Yes
Kaz, Inc.	Honeywell	HHT-013	55	55	65	85	Yes
Kaz, Inc.	Honeywell	HHT-013-HD	55	55	65	85	Yes
Kaz, Inc.	Honeywell	HHT-016-MP	55	55	65	85	Yes
Kaz, Inc.	Honeywell	HHT-055	68	49	80	76	Yes
Kaz, Inc.	Honeywell	HHT-057C	67	45	64	70	Yes
Kaz, Inc.	Honeywell	HHT-080	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-080C	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-081	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-081C	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-082-TGT	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-085-HD	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-090	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-090C	90	110	90	170	Yes
Kaz, Inc.	Honeywell	HHT-145	120	120	130	185	Yes
Kaz, Inc.	Honeywell	HHT-145-TGT	120	120	130	185	Yes
Kaz, Inc.	Honeywell	HHT-149	120	120	130	185	Yes
Kaz, Inc.	Honeywell	HHT-149C-CST	120	120	130	185	Yes
Kaz, Inc.	Honeywell	HHT-149-HD	120	120	130	185	Yes
Kaz, Inc.	Honeywell	HHT-155	146	118	148	182	Yes
Kaz, Inc.	Honeywell	HHT-155-SMS	146	118	148	182	Yes
Kaz, Inc.	Honeywell	HHT-157C	139	120	151	185	Yes
Kaz, Inc.	Honeywell	HHT-217	54	78	95	120	Yes
Kaz, Inc.	Honeywell	HHT-219	54	78	95	120	Yes
Kaz, Inc.	Honeywell	HHT-219C	54	78	95	120	Yes
Kaz, Inc.	Honeywell	HPA-050	55	52	60	80	Yes
Kaz, Inc.	Honeywell	HPA-050-TGT	55	52	60	80	Yes
Kaz, Inc.	Honeywell	HPA-051C	64	45	57	70	Yes
Kaz, Inc.	Honeywell	HPA-150	125	110	130	177	Yes
Kaz, Inc.	Honeywell	HPA-150-TGT	125	110	130	177	Yes
Kaz, Inc.	Honeywell	HPA-151C	134	120	151	185	Yes
Kaz, Inc.	Honeywell	HTT-022	54	63	62	99	Yes
Kaz, Inc.	Vicks	V9071	44	53	58	80	Yes
Kaz, Inc.	Vicks	V9071C	44	53	58	80	Yes
Master Brands Group Corporation	Whirlpool	AP25030K	215	205	224	320
Master Brands Group Corporation	Whirlpool	AP45030K	328	315	354	490
Master Brands Group Corporation	Whirlpool	AP51030K	325	315	401	490
Master Brands Group Corporation	Whirlpool	APR25130L	198	191	214	296
Master Brands Group Corporation	Whirlpool	APR25530L	198	191	214	296
Nano Biothys Company, LTD.	Nano Biothys	NBA750A	>400	>450	>450	698
Nano Biothys Company, LTD.	Zalmandn	NBA700A	425	394	434	610
Rexair LLC	AquaRainbow	E2	61	55	67	90
Rexair LLC	KingNeptune	E2	61	55	67	90
Rexair LLC	Rainbow	E2	61	55	67	90
Riccar	Riccar	RAPL	182	183	194	284
Riccar	Riccar	RAPM	126	117	138	180
Riccar	Simplicity	HHPL	182	183	194	284
Riccar	Simplicity	HHPM	126	117	138	180
Sears, Roebuck and Company	Kenmore	85150	98	98	103	150
Sears, Roebuck and Company	Kenmore	85264	330	300	380	465	Yes
Sears, Roebuck and Company	Kenmore	85300	197	197	214	300
Sears, Roebuck and Company	Kenmore	85450	298	291	343	450
Sears, Roebuck and Company	Kenmore	85500	182	183	194	284
Sears, Roebuck and Company	Kenmore	85501	142	138	145	213
Sears, Roebuck and Company	Kenmore	85777	89	97	110	151	Yes
Sharp Electronics Corporation	Sharp	FP-A40C	140	129	160	200
Sharp Electronics Corporation	Sharp	FP-A40U	140	129	160	200
Sharp Electronics Corporation	Sharp	FP-P30U	92	80	130	124
Sharp Electronics Corporation	Sharp	FP-P35CX	150	147	155	228	Yes
Sharp Electronics Corporation	Sharp	FP-P40CX	157	163	156	253	Yes
Sharp Electronics Corporation	Sharp	KC-830U	92	80	130	124
Sharp Electronics Corporation	Sharp	KC-850U	164	164	174	254	Yes
Sharp Electronics Corporation	Sharp	KC-860U	231	220	245	341
Winix, Inc.	Winix	5300	248	235	251	350	Yes
Winix, Inc.	Winix	5500	248	235	251	350	Yes
Winix, Inc.	Winix	9300	142	138	145	213
Winix, Inc.	Winix	9500	182	183	194	284
Winix, Inc.	Winix	WAC 5000B	184	175	197	270
Winix, Inc.	Winix	WAC-9000	182	183	194	284
Winix, Inc.	Winix	WAC-9000S	142	138	145	213
Woongjin Coway Co., LTD	Coway	AP-0509DH	112	84	109	130
Woongjin Coway Co., LTD	Coway	AP-1005AH	168	154	178	239
Woongjin Coway Co., LTD	Coway	AP-1008CH	175	155	193	240
Woongjin Coway Co., LTD	Coway	AP-1008DH	172	145	221	224
Woongjin Coway Co., LTD	Coway	AP-1009CH	182	149	203	230
Woongjin Coway Co., LTD	Coway	AP-1503CHE	226	214	283	332
Woongjin Coway Co., LTD	Coway	AP-2505CH	>400	402	>450	623
Woongjin Coway Co., LTD	Coway	AP-3008FH	>400	>450	>450	698
Woongjin Coway Co., LTD	Idylis	IAP-10-100	113	100	110	155
Woongjin Coway Co., LTD	Idylis	IAP-10-100 C	113	100	110	155
Woongjin Coway Co., LTD	Idylis	IAP-10-125	136	125	134	194
Woongjin Coway Co., LTD	Idylis	IAP-10-125 C	136	125	134	194
Woongjin Coway Co., LTD	Idylis	IAP-10-150	165	150	170	233
Woongjin Coway Co., LTD	Idylis	IAP-10-150 C	165	150	170	233
Woongjin Coway Co., LTD	Idylis	IAP-10-200	178	170	215	264
Woongjin Coway Co., LTD	Idylis	IAP-10-200 C	178	170	215	264
Woongjin Coway Co., LTD	Idylis	IAP-10-280	290	280	285	434
Woongjin Coway Co., LTD	Idylis	IAP-10-280 C	290	280	285	434

Further information on the Clean Air Delivery Rate can be found at http://www.cadr.org Air Purifier Guide neither endorses nor dismisses these ratings.

Sources referred to in this article:

Association of Home Appliance Manufacturers. "ANSI/AHAM AC-1: Method for Measuring the Performance of Portable Household Electric Room Air Cleaners" (PDF)
---. "What is AHAM's Clean Air Delivery Rate (CADR)?"
Sherbenou, Ed. "CADR: AHAM Capacity Certification."
United States Environmental Protection Agency. "Guide to Air Cleaners in the Home."
Wikipedia. "Clean Air Delivery Rate."

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