Bio Fresh Purifier

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Mitsubishi Bio Fresh $329.95 to $369.95

BioFresh HEPA Filter $39.95

BioFresh Charcoal based Honeycomb Activated Carbon Filter $19.95

Bio Fresh air purifier, designed and built in Japan by industrial giant Mitsubishi Heavy Industries, has begun to establish a US presence.

It has genuinely quiet, fully automatic operation and extremely low maintenance costs.

I believe these advantages offset its slightly high price to power ratio.

AirPurifierPower regulars know my secondary site theme concerning the struggle between marketing and engineering: here is great engineering with just average marketing. I consider that combination far superior to strong marketing of poorly engineered products.

bio fresh

Now sold primarily as the Rabbit Air SPA-421s, the Bio-fresh is marketed through a few websites, notably Amazon and eBay.

I see this machine as targeted at the Sharp air purifiers, as it resembles them and shares many features. These Japanese air purifiers tend to be designed from a global position of strength in electronics, with quiet motors and automation far ahead of competitors.

Information availability and consumer awareness is currently low, but the Mitsubishis/Rabbit Airs are growing market share., where the Bio Fresh has a fair sales rank, has 2 glowing 5 star reviews.

Bio Fresh is Mid-Powered but Quiet

No Clean Air Delivery Rate (CADR) has been certified, but I was able to find power and noise specs buried on the web. I am surprised at this difficulty, since these are outstanding in one key area: Noise. Everybody wants a quiet air purifier, one you can turn on and ignore. If I were selling the Biofresh, I'd have these sound numbers pasted all over.

The Air-Purifier-Power power to noise specification;

  • turbo 159cfm@45dB(A),
  • high 131cfm@39.9dB(A),
  • medium 95cfm@34.2,
  • low 60cfm@25.9dB(A)
  • and silent 39cfm@18.4dB(A).


That is very quiet, coming close to my industry leading FPN60CX Sharp! Particularly impressive is the low speed performance. I expect many users will sleep with the medium speed, and nobody will be kept awake by 18.4dB(A) on silent.

bio fresh air purifier

My estimated CADR, based on 159cfm and 90% high speed efficiency is 144. This is a bit weaker than the competition.

Sharp FPN40CX, selling a bit lower, has CADRs averaging in the upper 150's. This would not concern us, until we see the Bio Fresh air cleaner advertised as able to purify 600 square feet based on 2 air changes per hour (ACH).

While this statement is technically correct, 2 air changes per hour is not purified air, 6 is a minimum for reduction of airborne allergens.

Six ACH gives a maximum room size of 200 square feet, and Mitsubishis Biofresh might be actually able to purify that space, given its automatic and quiet operation. Most room size ratings are based on 24/7 noisy top speed operation, not the real world. For air cleaning satisfaction, over-install.

Price to power ratio calculation: CADR 144/$329 = .44 CADR/$, expensive if based on this criterion alone. Many air purifiers have CADR/$ above 1.0, but may lack the electronic sophistication of the Mitsubishi airs.

Mitsubishi Air Cleaner is Biocidal

Asia is way ahead of the "sleeping giant" (USA) in terms of biological threat awareness, and the "bio" freshening aspect of this air purifier is emphasized.

There is no photo catalytic cell, plasma ion, or ultraviolet lamp on the Biofresh air purifier. A 3-stage filtration process uses traditional filters with added germicidals.

Stage 1 is the nano-silver coated, washable, permanent pre-filter. Nano particle coating is a new technology, which coats filter fibers with tiny particles, creating a stickier surface. Silver has known germicidal capabilities. The prefilter captures large airborne particles like dust, hair, and larger microorganisms.

The 2nd stage is the "Bio" HEPA filter with which uses fibers coated with anti-influenza virus agent that can effectively lower the population density of airborne flu viruses. Tests by Japanese public health authorities demonstrated reduced concentrations of H3N2 influenza virus, which resembles H5N1, the epidemic threatening bird flu virus. The extent to which any air purifier can really protect against a viral contagion has yet to be demonstrated. It will have its chance.

Traditional HEPA purifiers allow for microorganism growth inside the air purifier.

I have a HEPA in my office that has picked up tiny fragments of insects, which have begun to support bacterial growth. This filter is not clogged, but makes an almost imperceptible odor when run.

Nonsense claims that this treated HEPA filter media can remove "cigarette odor" and "greenhouse gasses" detract from the effectiveness of Bio Freshs marketing campaign. Further marketing defects include misquoting the HEPA spec: "Traps airborne allergens and contaminants down to 0.3 microns in size, 99.97% of the time." (What does it do the rest of the "time"?)

With a scheduled $40 replacement every 3 years, HEPA maintenance is incredibly cheap.

Third is the charcoal odor filter, with a honeycomb arrangement, claimed to remove auto exhaust, VOCs (chemicals), cigarette odor, and general household odors. No weight of charcoal is quoted, and I expect the three year replacement interval is way too long in typical households.

But at $20, you could replace the Bio Fresh charcoal air filter as needed without undue cost.

Ionic Without Ozone

Here is another area where Asian engineering is forging ahead: ions and ozone. Stateside market leaders, (Ionic Breeze, Oreck, Ecoquest...) are mired in marketing gags, lawsuits and sparking ozone emitter air purification products. Don't look back fellas, something is definitely gaining on you.

Following the biofilters, air is freshened by a negative ionizer. No specs on ion density, emitter type or construction are given. However, the Biofresh is marketed as producing zero ozone. Negative ions without ozone is a favorite here at AirPurifierPower.

Purifies Air Automatically

The electronic controls on the Bio Fresh resemble the FPN60CX Sharp, with the exception that no oxidizing functions are activated. This means the automatic operating mode may be selected 24/7 without concern for those with impaired immunity.

The Biofreshener has dust and odor sensors and an elaborate display panel. It can regulate itself through all 5 speeds as airborne pollutant levels spike. This is a powerful feature, not a gimmick. Indoor air impurities are not uniform across time, they are sporadic.

Manually controlled air purifiers must be left running on expensive, noisy higher speeds to be effective. Automated air purifiers clean air more effectively at a lower overall cost.

There is also a "pollen" mode, which cycles the aircleaner periodically for seasonal allergy relief.

Of course, users can manually adjust any feature at will. I have seen forum posters question the utility of remote controls for air purifiers: they must be bouncy 20 year old males.

I love my remotes, especially in the bedroom, but also where the TV is concerned. Nothing is more annoying than the television-air purifier noise conflict. A handy remote accompanies the Bio Fresh purifier.

Air purification machines from the east have begun using 12 Volt direct current motors. These are quiet and dependable. The Mitsubishi design has no brushes to drag, make ozone with electrical arcs, wear out, or make noise.

In spite of the lack of photocats and other oxidizers, this is a technologically advanced air purifier.

Measuring 22.5 by 18 by 9 inches and weighing just 17 pounds, the Biofresh air purifier is easily portable, even up stairs.

Major components including the motor, filter, and air quality sensor are manufactured in Japan (not China).

Energy frugal, the "Bio" freshens air using only 33 watts on high and 7 watts on low. A 5 year warranty rounds out the low total cost of ownership picture for the Mitsubishi Bio Fresh.

Bio Fresh Conclusions

This is an innovative, sleek, automated, truly quiet, quality air purification product.

I expect long term low costs of ownership to offset purchase price premium.

If the Sharps are an example, retail prices may fall after the novelty wears off. Time will tell if the "Bios" will achieve the same popularity.

It is too soon to tell if customer service will measure up.

There is no Biofresh dirt on the web, and Rabbit Air has a good reputation.

I think the airborne biologicals represent the cutting edge in the air purifier challenge, and like the oxidant-free safety in the Bio Fresh approach. Will it work against the flu?

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Air-Purifier-Power Rating Criteria

Each of ten factors gets up to 10 points, 100 is perfect and very unlikely.

1. First do no harm; minimal out gassing, no ozone.

Score: 10 of 10.

2. Serious gas and odor removal is a requirement if health benefits are expected: Units with real carbon VOC capability rank higher.

Score: 8 of 10, carbon weight unstated, expect shorter charcoal filter life than spec.

3. Quality construction; case, gaskets, seals, and precision fitting eliminate bypassing and assure high efficiency at filtering sub-micron particles.

Score: 7 of 10, Info a bit weak here. How well it seals is not evident from ads, will await sophisticated user reviews or vendor tests.

4. The design maximizes the lifespan of each filter stage by allowing independent filter replacement. Ideally this is combined with electronic filter monitoring.

Score: 9 of 10.

5. Air cleaners have long filter life, low maintenance requirements, and reasonable operating costs.

Score: 10 of 10,

6. Purifiers produce low noise levels and meaningful air flow rates relative to noise.

Score: 10 of 10, real quiet.

7. Manufacturer has a track record, with many units in the field and a reputation for supporting what they sell. Warranty period and average service life are long.

Score: 8 of 10, young product, 5-year warranty good, service too soon to tell.

8. Purifier is a value in terms of price/performance ratio. Every price range should be included, “models above $1,200 are best”, while true, is not useful to most consumers.

Score: 10 of 10, worth the money, long term.

9. No dirt; unit and manufacturer should be devoid of class-action suits, high returns, recalls, consumer complaints, and legitimate negative consumer reviews.

Score: 8 of 10.

10. Air purifiers are stylish, portable, comfortable, and convenient for consumer use.

Score: 10 of 10, beautiful, handy remote, easy automatic interface.

Air-Purifier-Power Rating; 90, "I want a Bio"

See Rabbit Air 421a Review for more.

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