Re: Sharp Plasmacluster: Odor Sensors and Plasma Ionizer Safety

A Reader writes:

Ed,

Thanks once again for your input.

I was close to pulling the trigger on an Austin Air Healthmate Junior.

It was just short of what I wanted in noise level and power usage.

It was more than short on the automation side, and the missing odor/dust sensor just kept me back.

However, If I have kids, I think it would be the perfect purifier for their room.

I did end up getting a Plasmacluster fp-p40cx for $195 new on eBay after the recent 20% bing cash back event! I feel the light weight carbon issue can be fully taken care of by purchasing your own activated carbon and following your refill guide.

I have a few questions/concerns if you’re interested…

Odor sensor:

Despite not having a dust sensor, I’m very happy that the purifier has the odor sensor. Dust, and in fact anything larger than a micron, is not my primary concern.

I live in a suburban MI community with above average air quality.

I’m primarily concerned about smoke seepage from neighbors.

The odor sensor, I hope, will begin giving me some objective data.

Having said that, have you tested the sensitivity of your p40cx odor sensor?

My initial silly, but significant tests have included exposing it to: cooking smells (red sensor light), candle smoke (red light) and flatulence gas (red light).

Yes, I passed intestinal gas (expletive deleted) in the direction of my poor plasmacluster.

What’s it detecting, anyway? CO2? I didn’t think it could.

Possible methane? Maybe it was just coincidence. Good start, anyway.

My concern is that it always registers green otherwise. Well, maybe it isn’t a concern. Actually, it feels nice.

However, I want to make sure that this isn’t because it’s failing to attain an accurate baseline.

When we have guests, we always ask if they smell smoke, and no one is ever able to smell smoke.

I’m sure my wife and I are not crazy.

The smells are just extremely subtle.

A great effort to insulate this apartment from the other apartment was made by the previous tenant and management.

We don’t share ducts and have a closed loop HVAC.

I’ve unplugged the unit and plugged it back in a couple times to reset the baseline.

Always green. No detection.

I might try plugging it in outside and letting it test the outside air quality for a while, then bringing it indoors.

I read the faq on the dust sensor lacking. I’m sure this applies to an extent to the odor sensor as well.

Summary of concerns/questions:
How reliable is my odor sensor?
What is the technology driving the odor sensor?

Before I buy a home I will surely test the air quality with a VOC kit.

Filter system:

It’s interesting that the filter case simply sits upright in the machine with just a tiny bit of pressure from the front cover keeping it in place.

I’m surprised that this doesn’t allow any bypassed air.

Can you give me some reassurance on how well the chambered carbon bag filters odors? Correct me if I’m mistaken, but it would seem that gravity has the granules sit at the bottom of their respective chambers leaving a space at the top of each chamber.

Won’t a good portion of the air simply pass through this part of the carbon filter without being filtered?

Also, you’ve commented on the “sweet” smell coming from this purifier before on your website. However, I’ve seen you give a very different explanation than the one offered here:

http://www.sharp.ca/products/ion/pci_faqs.asp

Specifically, search for “smell” on the website.

About 1/3 of the way down

“In Ion rich environments (like your room with our air purifier), you will notice a sweet, perfume like smell due to the high ion concentration in the room. Rest assured that it is not toxic and will not harm you in anyway. In fact, it will only enhance the air quality within that room.”

Can you comment on this?

Plasmacluster technology concerns:

As I understand the technology (I’m not a chemist…), water passes through discharge electrodes and creates H+ and O2- ions.

This “naturally healthy shower” of ions is attracted to just about anything with some kind of polarity.

When the ions attach to whatever is in the air, they bond and the hydroxyl radical is produced and robs the object of its hydrogen.

On top of hydroxyl, one could also see small amounts of other oxidizers produced (O, O3, H2O2, OOH, and OO2), right?

With its new found hydrogen the OH radical returns to air as H2O.

What stops the hydroxyl radical from attaching to you?

The body’s magnetic field?

Why is no one discussing the health concerns associated with Plasmacluster technology?

Also, Sharp claims it is effective against smoke, but all the experimentation I see done is on viruses/allergens/bacteria.

Where’s the rest of the research?

Finally, what are some warning signs that a plasmacluster owner should look out for when running the positive/negative ion mode.

I don’t want the smoke in my home, or my somewhat new furniture to be the end of my health.

My information is mostly from:

http://www.sharp.co.jp/plasmacluster-tech/en/files/86-01.pdf

I’d much rather read about this in a refereed journal. Have any literature?

One more… what is the benefit of running the negative ion mode? Are ALL cities/towns lacking in negative ions?

Can an excess of negative ions be trouble as well?

Hope this isn’t too much to take on, but I don’t just buy a product.

Overall, I’m pleased so far, but I doubt I will ever trust Sharp.

Ed's Reply

Hey Reader;

Miniature electronic sensors have appeared everywhere in the last three decades. Electronic nose technology has evolved - sophisticated and expensive.

The more sensitive technology is used by military and law enforcement, but so far cannot beat the cost-effectiveness of man's best friend, the drug and explosive sniffing dog.

But there are also cheap, like five bucks each, smoke and odor sensors. I suppose the sensors in air purifiers are near the lower end.

Sharp Odor Sensor

Odor detectors on mass-market air cleaners have inherent cost limitations. Operationally, they need not to be too sensitive.

Gas molecules diffuse from point sources, so the close-proximity tests you have tried, which produce concentrations high enough to trigger the sensor's switch, will always work.

Inexpensive gas pollutant sensing has generated user reports of air cleaners being activated by many smells;

a whiff of cigarette smoke from a smoker getting close, without a lit cigarette,
microwaving popcorn,
chlorine bleach vapor,
door opens,
frying, especially bacon,
bath needed,
removed shoes,
cooking,
vacuuming,
toaster working,
pet near air purifier,
cat visited litter box,
light or blow out a candle,
incense lit,
dishwasher working,
household "cleaners" used,
aerosol spray deployed,
flatulence, (you are not the first to try this).

But it is too expensive and impractical for the sensitivity to be set higher. Early Sharps had a selector so users could select more or less activation. This feature fell victim to 2009's recession and weakness of the US dollar.

Everyone has experienced this issue with the common household smoke detector. These can be set to detect lesser levels, but become very annoying when it's just dinner cooking and the fire alarm keeps squawking.

Low cost sensors are often too sensitive to changes in humidity, and cannot detect changes in concentration of odor mixtures - as opposed to merely detecting their presence.

I have found no specifics on which chemicals any air purifier's odor sensor can or cannot detect. Specifics of construction and technology used in the Sharps are elusive.

I'd be glad that your new FP-P40CX always shows "green" air quality, even though you still smell the subtle smoke presence.

Again, cost and practicality rule against sensitivity sufficient to detect the most subtle diffuse odor, which in the case of smoke, is distributed through every aspect of the building.

I suggest you have a cigarette odor removal "dust up" - run fans and shake things, these gas molecules attach to house dust - while any and all air purifiers run on high. In your case, maybe a week like this, before depending on Auto Mode.

In my wife's Houston apartment we have had a cigar guy who put off a horrible stench, and a frequent balcony barbecue guy who liked to use a whole bottle of charcoal lighter. The FP-N60CX sensors would always light up, about the same time we noticed the smell.

I left my Sharp near the open window in Houston, where it was very effective at monitoring incoming outdoor air, allowing me to shut the window on bad air days, and breathe fresh air otherwise.

At the ranch, air is clean until winter, when the burn ban signs go down and neighbors rattling chain saws say wood stove fires will soon be casting their cheery glow on happy faces.

And creating the worst air pollution outside a refinery district.

I have 3 Sharps, the oldest over 4 years. I am very confident of the air quality information they provide. But I still do the dust up thing for a few hours every couple weeks.

Sharp Bypassing

Because many users will not replace filters frequently enough to protect motors from burnout, manufacturers design-in bypassing to assure airflow to the motor.

This is pandemic in the industry, and many marketing tricks are used to hide bypassing from the naive consumer.

It is common for air purifiers in the $300 price class to leak air past loose fitting filters. So we do not judge this class on an absolute basis.

The Sharps are no exception, filters are held relatively tight by pressure from the prefilter clips and front panel snaps. I'd estimate particulate efficiency in the upper 80's, good for the price, as typical.

Fattening up the carbon bag, as I do, will add to this pressure, but must be done carefully so as not to damage the HEPA. I seal the edges of the filter cassette with scotch tape on occasion.

But remember that the Plasmacluster oxidizers are destroying many airborne fine particles too.

To get near-100% efficiency, you'll have to go to premium-class, $1000-plus air purifiers.

Carbon Bag Odor Efficiency

The Sharp carbon bag has been shrinking right along with the general 2009 cost cutting in the industry.

It is easy and cheap to add maybe 20% more carbon to this bag, within the limits of space. This will expose a greater cross section of carbon to airflow.

But any carbon filter is a merely a pile of granules, with space for air to flow between. Carbon odor filters are never more than about 75% efficient, and this varies widely - gas phase molecules are adsorbed differently depending on ionic charge and polarity.

This is why the oxidizing air purifiers - plasma-ion, photocat, uv, and ozone, are rising in popularity.

The sweet odor from carbon filter issue is unrelated to the slight hint of "forest air" in ion rich environments.

Plasma-ion Safety

First, somebody (Me) has been discussing the health concerns associated with Plasmacluster technology. Every Sharp review here carries a discussion and warning about using oxidizing agents, such as hydroxyl radical, in rooms where people/pets are present.

You are correct, there is nothing stopping the oxidants from attacking your body. I assume, as you do, that a "free radical cascade" is triggered, with smaller amounts of other oxidizers present.

I have been at times completely disabled by environmental sensitivities. I have an eye which has been injured in a construction accident and undergone several surgeries. This eye injury and the suffering that went with it bore an unexpected gift. It is exquisitely sensitive to irritants of any kind, and a good overall indicator of systemic inflammation levels in my body.

Sitting near the Plasmacluster when oxidizers are being emitted, I will soon notice the eye, and my very experienced left nostril, starting to itch.

This is no worse than rush hour traffic, but I don't play in that either.

So I advocate intelligent use of the plasma-ion oxidizers because they are soooooo much safer than the ozone saturation air cleaners which totally dominated the market when I started air-purifier-power.com.

Unlike ozone, plasma ion clusters do not persist in indoor spaces, they are gone within seconds when the machine shifts modes or is shut down. While manufacturers claim they work throughout the room, the ion density is inverse-square proportional to distance - they are strong close to the air cleaner, and weaken quickly as you move away.

When I first got my 2005 Sharp Plasmacluster FPN60CX, a small houseplant was tested by putting it on top of the machine, with pos-neg blue light plasma on for a couple days.

Parts of the plant directly in the airstream wilted after 24 hours.

The leaves furthest from the air flow were not damaged.

Although no control was ever run - a similar plant so exposed, while the plasma was off, might have been damaged by dehydration(?) - this, and my long experience, reinforces my opinion of the localized action of the plasma-ion oxidants.

My position is this: If the contamination is strong enough to trip the sensors, you have a serious air quality problem. Remove the source! Then go for a walk and let the air cleaner work.

Individuals will vary in their susceptibility to the oxidants. Those with suppressed immunity, chronic inflamation, metabolic acidosis, and other health issues should avoid contact with plasma-ion oxidants. But with the Sharp remote, this is easy, users never need approach the machine in plasma mode.

Negative Ion Mode

Negative ions are a controversial topic, highly politicized over the past 40 years.

The initial research was largely Russian, which during the cold war was repressed.

Neg ion generators were once popular as health devices, until the friendly federal government banned advertising them as having health benefits.

Hospitals began installing them, especially in burn wards, where exposed skin healed visibly faster with neg ions.

Well, to me an FDA ban is the surest evidence of efficacy any alternative remedy can be awarded. I ran out and bought an ion generator in 1977.

Today I have three IG-133A room ionizers from negativeiongenerators.com -

The basic concepts of neg ions are presented in "The Ion Effect", by Fred Soyka, published by Bantam Books in the late 1970’s.

In a nutshell: vehicle exhaust particulate matter, postiviely charged (oxidation, any burning, is a loss of electrons), highly prevalent in urban environments, flocculates electrostatically, condensing negative electrical charges and falling to the ground.

This leaves the air positively charged, itself an oxidant.

I do not believe any room air purifier can create a surplus of neg ions large enough to be a danger with so much pos-ion pollution around.

Trust a Corporation?

I do not share your notion of "trusting" Sharp.

While I promote their products, this is a giant corporation.

I do not trust them, or for that matter, refereed journals, Consumer Reports, government anywhere at any level, news media monopoly, academic research based on grants and sponsors.....

Which leads us to what I consider the most important question - why so much interest in the virus?

The Viral Panic Room

Since the advent of AIDS/SARS/Ebola, "viral marketing," which formerly was an internet promotional tactic, has taken on a new meaning.

We recently have been subjected to a vast campaign centered on the H1N1 "Swine Flu epidemic." Some see this as merely a marketing campaign for big pharma. Others see more than that.

Asia, with its high population density and recent SARS experience, is more acutely aware of these issues than we are in the "safe" USA.

So Asian vendors focus on marketing based on anti-microbial capabilities of their products.

But they do not toil alone.

I recently stopped at Half Price Books for Christmas gifts. I also bought four titles for myself;

The Hot Zone, Richard Preston, (Ebola virus),
The Coming Plague, Laurie Garrett,
Flu, Gina Kolata, (1918 Flu),
Microbe, Alan P. Zelicoff, M.D.

I remain very skeptical of air purifier vendor claims of "flu prevention," but advise readers to prepare.

Likewise claims of "effective against smoke" are dubious. At the bottom of every single page, I have a footer that warns against believing this.

But doing the dust-ups and running purifiers on on medium speed even when auto mode sensors select silent will, over time, reduce your smoke seepage issue.

Best wishes for better health,

Ed