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IAQ (Indoor Air Quality) Irritants


We love plants, or we should, because they provide nutrition, they convert our gaseous exhaust (carbon dioxide, or more commonly CO2) into Oxygen that we consume continuously, and they provide beauty in the form of shapes, colors, etc. However, in order to propagate, they must pollinate. And pollinate they do, right into our very noses. Pollen, the small "seedy" part of plant anatomy, is either scattered about by pollinators (bees and other insects) in a long-term fashion, or by wind in a short-term fashion (sometimes only lasting a week or two per year). The latter is a cause of aggravation and suffering for many individuals who on an ongoing basis suffer from congestion, sinusitis, and a reduced ability to breathe. Aside from the destruction of all plant life on the planet (a course of action Not recommended), the only alternative is to be indoors. Simply being inside a shelter one is protected from the seasonal onslaught of innumerable and varied kinds of airborne bodies intended to make plants propagate, and their indoor concentration is generally lower than outdoors due to the protection from meandering air currents. For a reduced presence, one can use a stand-alone air filter unit, which will reduce the particulate concentration in one or more rooms. When that shelter is additionally equipped with a central air mover and distribution system, the indoor concentration is bound to be several magnitudes lower than outdoors. Unfortunately, everyone does not have such equipment, so some are left to their own cognizance of when the pollen season is expected, for certain of the most irritating pollen producers such as ragweed, and to seek appropriate protection indoors. Size-wise these are the heaviest, and produce a layer of fine colored "dust" on horizontal surfaces, until a breeze again lifts them up. Being organic, they form an excellent and diverse food base for bugs small enough to benefit from it.

Animal and Human Dander

We itch, and scratch ourselves, so do animals. In the process copious amounts of hair and skin cells are shed. Over time these droppings congregate into "tumbleweeds" that locate themselves near wall-to-floor intersections. Over additional time, these acquire names, and seem to follow us around, screaming "It's time to cleeean!" Those who have carpeting have a superficial cover-up. The shed material collects within the matting of the carpet, and gradually provides a dirt layer to complement the carpet matting "forest." As individuals walk over carpeting, each footstep temporarily crushes the matting and forces localized air currents that liberate some of the accumulated dust for us to inhale, and depending on size (as shown below) may remain available for inhalation for hours. We have come full circle!

particle settling times

The idea is not to scratch . . . so try to teach that to a dog, cat, or other animal. But really, the cure is a regular cleaning regimen. It does not need to be extreme, but it needs to be regular and address the areas that are the most prolific sites of collection. Those areas exist underneath every piece of furniture, especially those that get moved the least, and even more especially those whose function causes them to have a recurring forced flow of air around them, such as a refrigerator due to its cooling coil operation, or baseboard radiators. I have many times come to visit and found copious amounts of dust under various pieces of furniture to such a degree, that I am left wondering how many years (decades?) it had been since some of those areas saw a vacuum cleaner hose. I have seen some refrigerator bottoms that appeared to be repositories of a dead cat. Being organic, this is part of the food base for small bugs, such as dust mites.

Dust-mite Debris and . . . Dust

Dust-mites are aptly named because they are mites that live on and in dirt, because it's organic (as from the paragraphs above). They eat it and produce microscopic droppings that are a potent allergen. We humans are not keen on eating bug droppings, but we do it a lot, ignorantly, because we do not know where the dirt is, and what lurks on and within it. The dirt gets into our sinuses and lungs by a process akin to that from a leaf blower. Previously described herein, at the risk of being redundant, allowing dirt to collect, and then stepping on it, causes it to go airborne. Some have stated that "we are what we eat," and I submit that "we eat what we do not pay attention to."

It may be a no-brainer, but more dirt = more problems. Dust mites are opportunistic. Present everywhere, their available concentration cycles with the concentration of organic debris, which can be vegetative remains, degenerative remains , or carnivorous remains, as described above.

Along with dust, viable (with life) or not, comes a cleaning regimen. A vacuum cleaner is a wonderful thing. It collects dust for easy disposal. However, most vacuum cleaners have a collection efficiency limit of about 5 to 10 microns (millionths of a meter), which is about the same efficiency of our noses. Thus they trap the visible and leave most of the invisible go though the filter and become evenly distributed. I have never seen a pollen or mold spore look at me while I was looking at it, because most are too small for the naked eye, which can only discern object larger than about 10 microns. Many central air systems have a filter that is even worse, whose trapping ability may begin around 100 microns (0.1 mm), primarily designed for machine protection, most likely during initial construction, and then replaced with identical ones by the homeowner. HEPA (High Efficiency Particulate Air) filter equipped vacuum cleaners presently may cost as little as $100, while improved filtration for a central air machine may cost $4. But even with filters, they need to be cleaned or replaced, in order for them to function as intended. With central air systems, a more pressing problem arises, because a poor filter allows easy accumulation of dirt within the cooling coils, the air mover blades, and the subsequent air ducts. When this dirt becomes sufficient, it becomes a haven for the same biota previously discussed, and propagation of it through the entire home each time the machine operates. Considering that the air mover causes air turbulence (great for heat transfer), should alert those affected that if they see particulate emissions from the air duct openings (made airborne by the turbulence), there is an immediate and dire need for cleaning the internals, which cleaning might not have been needed, had a better filter been used.


Molds are necessary agents of recycling and exist everywhere. They slowly devour most surfaces they come in contact with, reducing them to their basic chemical constituents. If the surface is inert, as in metal, then they may simply feed off the dirt on its surface, even if vertical. Particularly attractive to mold are surfaces containing cellulose. Cellulose is the main component of wood and its derivatives, such as paper. Cellulose is also a structural rearrangement of simple sugars that gives the assembly great structural strength, and great nutritional value when decomposing due to excessive water content, rendering it easily digestible by mold.

Biota Size perspective

Molds thrive particularly well on moist surfaces. Modern dwellings are outfitted with a plumbing infrastructure that penetrates many structural walls. Any leak (however small) provides the proper environment for mold to colonize. Inattention to the leak(s) for greater than 24 to 48 hours, promotes conditions appropriate for rapid growth (amplification), changing a microscopic presence into macroscopic (visible) mold growth (colonies). Allowing ambient moisture content to rise above about 65% will provide similar favorable conditions for growth. Continued favorable conditions can allow sequentially more aggressive species (whose frequency of occurrence indoors is generally very low) to manifest themselves, possibly feeding off the dead mold colonies they replace. While many species are allergenic, some species are toxigenic, mutagenic, and carcinogenic. When molds colonize a favorable surface they produce a mycelia that penetrates the surface, in some respects similar to a plant's root system. They also produce outcroppings (similar to plant's trunks and branches) that produce spores. When agitated, or physically or chemically stressed, these spores easily become airborne. You should easily begin to see that simple surface treatment of mold infestation on a porous surface is a cheap and incomplete solution, when the causative factor is not addressed.

In a properly controlled environment, airborne mold spores, available continuously, settle out on clean surfaces and begin to form a microscopic layer of biota. Although inert, because the humidity does not promote growth, they are nonetheless organic, and can form a food base for bugs small enough to benefit from it. For more specifics see Mold


Bacteria, as most other particulates are ever-present. They, like mold, appreciate surfaces that have been made wet from leaks. Their food base requirements vary depending on the genus (similar with molds), and their propensity to cause trouble is mainly evidenced by leaks that go untended, maybe because "it's the landlord's problem," or because "it's somebody else's job." They may produce aromatics that are telltale, or not, depending on the many variables necessary to foster massive growth spurts. As with Molds, These growth spurts are known as "Amplification." Since the factors favoring amplification may not be constant, the cyclic chemical and physical stresses forced onto the opportunistic biota forces them to cast off portions of their structures, which then become airborne.

Identification of problem areas associated with viable particulates should be focused oon the cause, not the effect. A leak or high moisture is the cause. Excessive mold, dust-mites, or bacteria is the effect. Removing the mold and leaving the cause will allow the mold to reoccur, similarly with bacteria.


Some of the smallest particulates, viruses have a very limited lifetime outside a host. Their existence, however, can be lengthened somewhat if they find a receptive surface rich in nutrients. Surfaces rich in mold, dust-mites, and / or bacteria, may provide such a surface. The solution centers, as before, on a regular cleaning regimen.

Some Indoor Solutions:
1) reduce the installation of wall-to-wall carpeting,
2) if carpeting, use shorter pile to reduce dust accumulation,
3) use a HEPA vacuum cleaner,
4) clean behind and underneath furniture _ regularly,
5) clean baseboard radiator fins (pressurized air can, and vacuum cleaner,
   make the air flow the opposite of the way it normally would),
6) improve central home ventilation with improved filtering,
7) install local air cleaners for continuous operation;

Some Outdoor Solutions:
1) use a vehicle air filter for motor vehicles,
2) use a particle air mask, especially when stirring particles, as in yard activities.


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