Every few weeks, I get an eMail describing a 2,000 square foot open floor plan interior space, often with high ceilings.
The area may have standard HVAC or a complex heat exchanger with additional ducting and fans.
External factors may include wood smoke, freeway proximity, or prevailing wind pollutant sources.
Occupants may suffer allergies in multiple combinations.
After the introduction, the reader asks me, the great air quality guru, to prescribe one or two air purifiers which I can guarantee will resolve all the particulate issues in the described space.
After many years of this routine, I respond to all such inquiries with "Buying a laser particle counter is the only way to "guarantee" your indoor air quality."
I had used air purifier industry leader IQAir's .3 micron laser particle counters on a variety of air cleaners and found that cheap air cleaners tended to exhaust lots of fine dust and quality air purifiers didn't.
Most of us already know that.
So I returned the particle counter, thinking it hadn't taught me enough to be worth the $2K price tag.
I pestered the IQAir reps about putting sensors on IQAirs.
IQAir said sensors commensurate with their overall quality would cost many hundreds of dollars, pricing their products out of the market, without making a real contribution to purifier performance.
In 2005, as I began writing air-purifier-power.com, sensor-driven automated air cleaners seemed to be the wave of the future.
Japanese electronics giants, like Sharp and Mitsubishi, had built modern air cleaners that were light years ahead.
These had long lasting HEPA filters, quiet BLDC motors, air quality sensors, and clever LED displays.
Very inexpensive particulate and odor sensors appeared to be an integral part of the revolution, and were soon copied by Korean and Chinese builders.
A considerable amount of my air purifier intelligence gathering comes in the form of reader feedback.
Evidence began to trickle in, with trusted contributors suggesting that the sensors used on mass market air cleaners were ineffective, more of a sales gimmick than a benefit.
I belatedly realized that testing an air purifier's emissions at the exhaust port, as is done in hundreds of Youtube video air cleaner ads and "reviews," was only the beginning.
So I bought the Dylos DC1100 Pro .5 micron "For Air Purifier Test" laser particle counter and tested the actual performance of my air cleaners over a period of time.
The result: sensor-driven air cleaners fail to deliver, tending to clean a local bubble and then shut down, showing the user a "green" condition which does not accurately depict the room's particulate density.
I learned that testing the particle density in the room as a whole is the only way to know if the air cleaner(s) are doing their job.
We are asked to trust vendor room size ratings, almost universally based on low air change per hour numbers, as the basis for removing invisible particles polluting our home's air.
This was not economically feasible just a decade ago, since commercial particle counters, used in clean rooms, hospitals, and labs, start at several thousand dollars.
Dylos Corporation's DC1100 Air Quality Monitor is designed, and priced ($199.00 - $320, depending on features) for residential users, who need consistency, not scientific precision.
DC1100s have two readouts, displaying small and larger dust particle readouts.
The standard model has 1.0-micron and 5.0-micron thresholds.
Dylos can calibrate for .5 micron thresholds for a few dollars extra, with the Pro model displaying particle counts above .5-microns and above 2.5 microns.
Air quality aficionados will want the "Pro" version, NOT the standard model.
DC1100 is carried by several reputable online vendors, including Amazon.com, Sylvane.com, and Air-Purifiers-America.com.
Dylos particle counters are marketed in the UK under the Gradko International brand.
DC1100 is a real laser, unlike the inexpensive sensors built into air purifiers.
Dylos particle counters can be used outdoors, though the lower-priced models are not cordless.
Indoor air quality is very dependent on outdoor air.
Knowing whether opening windows will improve or worsen indoor air quality is a major advantage.
I run my purifiers much less now, using windows and exhaust fans whenever outdoor air is clean enough in my rural location.
Urban dwellers may not be able to do this as often, since only cold fronts sweeping down from Canada may produce suitably clean outdoor air for venting.
Dylos literature warns that readings can be inaccurate in direct sunlight.
Outdoor particle counts can have a very large range, especially in places like the Los Angeles basin.
When humidity is high (greater than 80% relative humidity), readings will affected by the number of water vapor nanoparticles, since DC1100 has no relative humidity calibration.
Many new users fail to take this into account, thinking the DC1100 is unreliable.
Running the particle counter in a given room with air purifier(s) for about a month will give the user a relative sense of how well the installation is working.
The digital displays show the running average of the particles counted in the past 10 seconds.
Dylos readouts represent the number of particles per cubic foot divided by 100.
Multiplying by 100 gives the actual particle density.
A rapidly oscillating dynamic bar graph shows instantaneous readings.
Some user reviews found the motion distracting when in the peripheral vision.
There is no substitute for visible feedback when you have pollutant sources in the room.
Many "HEPA" vacuum cleaners have seriously unhealthy exhaust emissions, and the DC1100 can prove it.
The photo at the right depicts my DC1100 being used to verify that using water to wash out a full vacuum cleaner dirt bin (Shark NV356e) releases far fewer airborne particles than the standard dry dumping method.
If you have deep-pile carpeting, with the DC1100 you'll find out just how dirty it is after the vacuum has run.
When activity in the room stirs up dirt, it will show up almost instantly on the Dylos.
How many particles are being added or lost when the HVAC comes on?
DC1100 knows, calling attention to the need for duct cleaning, new furnace filters, or the effectiveness of any new HVAC filter upgrade.
DC1100 will evaluate your air quality as a blind approach cannot.
The Dylos particle counter tells you if a $200 air purifier works well enough that the $800 model will not be necessary.
Or if the current installation is not sufficient, and additional expenditures may be required.
For instance, folks with mold and pollen allergies may not need to buy a premium air cleaner.
These larger-than-2 micron allergens can be controlled by many $200-class machines - monitoring larger particles using the right side readout on DC1100's display can help such users.
I find my Dylos 1100 is better than a second air cleaner for getting actual clean air in a room.
A clean air freak, I was in the habit of total overkill, running as many as three air purifiers in my bedroom.
The three air cleaners are still there, but run simultaneously only when needed, such as during the Bastrop County (Texas) wildfires of 2010.
For years my dear wife has suffered random episodes of severe allergy, confined to our bedroom, that confounded my efforts to prevent.
Until the DC1100 arrived.
keep our bedroom shut all day, both the door and windows,
run HEPA-sealed vacuum cleaners at least weekly,
and wash the 100% cotton bedding more often than seems necessary, as the particle counter has taught me that bedspreads and pillowcases collect invisible coatings of dust close to the sleeper's nose.
As evening approaches, I'll go to the bedroom to prepare it for the evening's TV viewing and sleep.
I turn on the DC1100 particle counter and both air cleaners, leaving them running on high.
Only when the particle count is very low will I turn the air cleaners down.
Generally this takes longer than one would expect.
One air cleaner runs on low for the night, unless particle counts rise, and is turned off for the next day.
Doing this routine rigorously has completely eliminated my wife's nagging nighttime allergies, after years of failure using air cleaners running 24/7 on low or auto.
Air cleaner filters are a high margin consumable, and represent a significant portion of the long term cost of clean indoor air.
HEPA filters are expired when restricted, not when a time limit is reached.
Yet replacement filters are nearly universally marketed as being necessary on timed intervals, regardless of the actual conditions of use.
I have 2 IQAirs and a Sharp Plasmacluster running HEPA filter life-extension experiments now.
The same HEPAs described above in the bedroom-allergy scenario.
These HEPAs are protected by extra prefiltering and frequent careful vacuuming, to prevent particles larger than 2.0 microns from loading the HEPAs.
Currently the older IQAir and the Plasmacluster have seven year old HEPAs, filters that are collectively worth more than the price of the particle counter that tells me they are still working perfectly.
All these air cleaners have "change filter" lights showing, and the Dylos DC1100 has saved me a substantial percentage of the replacement costs.
The Dylos runs on 120 Volt AC and must be near an outlet to use.
DC1100's plug-in power adapter draws .22 Amps and outputs 9 Volt direct current.
Particle counter readings tend to fluctuate, requiring the user to mentally average readings over a few seconds.
My Dylos fluctuates more widely than the IQAir did.
Many user reviews mention the awkward size of the DC1100 as compared to a battery operated handheld model.
DC1100 draws air in at the bottom rear and exhausts it at the top.
A small computer-type fan draws the air through the Dylos.
In continuous mode, my DC1100 is louder than a desktop computer, just background noise, but sometimes if I'm cranky it is an extra irritation.
Computer connectivity, through an old fashioned RS232 9-pin serial connector COM port, is optional on the DC1100 and standard on Dylos' higher priced DC1700 battery-operated Air Quality Monitor.
Some sophisticated reviewers have complained that this interface is obsolete (it requires a USB adapter to fit newer PCs).
Software is available for graphic displays and long-term air quality monitoring.
I don't think these applications are relevant to most air purifier buyers.
I also find the Dylos' history mode less interesting than short term real-time feedback, but it is standard on DC1100s.
Recording up to 30 days of minute, hour, or daily data, the Dylos switches itself on and off to take readings for periods specified.
According to Dylos, the following readings on the small particle (left) side of the meter correspond to air quality;
For the Standard DC1100 1.0 micron model;
1000 + Very Poor
350 - 1000 Poor
100 - 350 Fair
50 - 100 Good
25 - 50 Very Good
0 - 25 Excellent Air Quality
For the Pro model (.5 microns);
3000 and above = Very Poor
1050-3000 = Poor
300-1050 = Fair
150-300 = Good
75-150 = Very Good
0-75 = Excellent
Obtaining "excellent" levels, even in rooms like mine with over-installed air purifiers, requires sustained high speed air cleaner operation.
I conclude that the vast majority of air cleaners in America, almost all of which are installed in spaces too large for their real air cleaning power, are failing to deliver healthy air when used as directed by the manufacturer.
2900 Adams Street, Unit C38
Riverside, CA 92504
User reviewers agree that Dylos customer support is very professional, and that out of warranty repair or recalibration is quite reasonable.
User maintenance is limited to cleaning dust out with the same canned compressed air used to clean computers.
Dylos recommends covering the DC1100 when not in use to keep dust and other intrusions out.
DC1100 has been on the market since 2006, with few complaints concerning reliability.
Laser diodes will eventually wear out, but life expectancy is at least several years.
After a few months of heavy use, I know what to expect in terms of particulate counts, and keep my DC1100 off much of the day, using it in the evening as described.
I recommend purchasing the Dylos "Pro" version for anyone who intends to spend money on air purifiers, and their filters, in the future.
Unless you have no air purifier at all, I'd consider buying the Dylos DC 1100, instead of another air cleaner for the same room.
It will teach you more about what you are actually breathing, and allow you to improve your home's indoor air, faster than any other method.
Folks with health/asthma/allergy issues can benefit directly.
Others can save money by using the DC1100 to evaluate air purifier and filter performance.
See the .5 micron
Dylos DC1100 Pro air quality monitor at Amazon.com.
Dylos DC1100 Review