Bau-Biologie: How I Reduced House Dust in My Home

Not being allergic to house dust, I never really gave it much thought. I didn't even include it as an indoor air pollutant in my book Home Safe Home. But when I had my Bau-Biologie Home Inspection, I learned a few things about dust that made me want to make some changes to reduce the amount of dust in my home.

The composition of house dust varies from house to house--and I don't know the exact contents of mine--but, in general, it could contain decomposing insect parts, pet dander, human and animal hair, food leftovers, pollen, mold spores, bacteria, skin flakes, insulation, sand, textile fibers, and the infamous dust mite and its fecal material.

According to the Environmental Protection Agency, many of the components of house dust are considered "biological contaminants" of indoor air.

"Biological contaminants," says the EPA website, "include bacteria, molds, mildew, viruses, animal dander and cat saliva, house dust mites, cockroaches, and pollen. There are many sources of these pollutants. Pollens originate from plants; viruses are transmitted by people and animals; bacteria are carried by people, animals, and soil and plant debris; and household pets are sources of saliva and animal dander. The protein in urine from rats and mice is a potent allergen. When it dries, it can become airborne. Contaminated central air handling systems can become breeding grounds for mold, mildew, and other sources of biological contaminants and can then distribute these contaminants through the home...

"Some biological contaminants trigger allergic reactions, including hypersensitivity pneumonitis, allergic rhinitis, and some types of asthma. Infectious illnesses, such as influenza, measles, and chicken pox are transmitted through the air. Molds and mildews release disease-causing toxins. Symptoms of health problems caused by biological pollutants include sneezing, watery eyes, coughing, shortness of breath, dizziness, lethargy, fever, and digestive problems."

In addition, new studies are finding that toxic chemicals and metals can attach to house dust, which we then inhale. A study on the house dust in Ottawa, Canada found elevated levels of lead, cadmium, mercury, arsenic, and other metals in common house dust. Another study done by Greenpeace in the United Kingdom found styrene, pesticides and plasticizers in house dust. And a study done in the United States, just released in March 2005, showed that seven groups of toxic chemicals--phthalates, alkylphenols, pesticides, polybrominated diphenyl esters, organotines, and perfluorinated chemicals--were found to be present in the vacuum dust of all sample homes tested. Phthalates, which are used primarily as plasticizers for polyvinyl chloride plastics (PVC)--also known as "vinyl"--made up nearly 90 percent of the total concentration of chemicals found in the dust.

Of course, if you don't have sources of toxic chemicals in your home, you wouldn't have much in your house dust, but these chemicals may be present in places that are not obvious. Wool carpets may have pesticide residues that can attach to house dust. PVC could be coming from shower curtains, flooring, black-out curtains, air beds, and other soft plastic products.

Most surprising to me was to find out from the Bau-Biologists that molecules of toxic substances can enter your home in various ways and then attach themselves to house dust. In addition to traveling indoors through open windows and on clothing and shoes, negative air pressure caused by forced air heating and cooling can cause houses to pulls up dust from under the house. If it's an older home, that dust can be loaded with pesticides such as chlordane and even DDT.

According to certified Bau-Biologist Mary Cordaro, "We almost never smell these semi-volatile organic chemicals (SVOC's), even though the levels increase with time. I would also stress that these chemicals do not dissipate over time fast enough, because they don't outgas the way VOC's do. They are very persistent, and we breath them in along with the dust. The older the material, the more of the chemicals get into the dust as the material breaks down."

Currently there are no laboratories here in America that test dust samples for SVOCs. "Sampling air or dust for VOC's is not adequate," says Mary. "And since it's very expensive to test for SVOC's, and the only lab is in Germany right now, it's best to simply eliminate as many sources as possible, and control the dust loads in the house with fresh air dilution, HEPA filtration, and a building science approach to HVAC to stop the pulling of chemicals from beneath the house that happens in almost everyone's home."

OK. That was enough. I was convinced it was time to control the house dust whether I was allergic or not. Come to think of it, both my husband and I had been sneezing more lately...

HVAC Filters

The first recommendation in the Bau-Biologie Home Inspection report was to upgrade the replaceable filter in my HVAC system with a 3M Filtrete Air Cleaning Filter. We just had a cheap filter than removed only large particles.

The 3M FIltrete filter is rated MERV 11. MERV is short for Minimum Efficiency Reporting Values. It indicates a filter's ability to capture particles of different sizes and is useful in comparing the performance of different filters. The higher the MERV rating, the smaller the particle it can trap.

In addition to MERV, there is also a Filter Effectiveness Rating, which is a relative measure of a filter's initial efficiency at removing particles less than 1 micron in size. The higher the rating, the better the filtration efficiency. My old fiberglass filter had a Filter Effectiveness Rating of 38. The new Filtrete filter has a Filter Effectiveness Rating of 1250.

This filter can trap pollen, mold spores, dust mite debris, pet dander, household dust, smog, bacteria, and particles that can carry viruses.

It was $15 to purchase one filter the right size for our system, but it lasts three months. Our previous $5 filter had to be changed every month, so even though the initial cost was more, it averages out to the same expense over three months. And our air is much cleaner.

This is one of those big improvement for little change items. I recommend this step for everyone.

We had no problem finding this filter at our local Home Depot.

While we were at Home Depot, we found another brand of filter that cost only $10--one-third less. The NaturalAire Microparticle Air Filter has a MERV rating of 10 and a Filter Effectiveness Rating of 1000, so it is slightly less efficient. The label says it captures and reduces particles as small as 1 micron, including microscopic allergens, mold spores, smoke, pet dander, pollen, cooking smoke, dust mite debris, and household fibers. It also contains baking soda to deodorize the air. We bought one of these too. It's not as effective, but may be enough with the other measures we are taking.

That the filter we had wasn't doing it's job became apparent when we had our air ducts inspected (see below). The duct right on the other side of the intake vent was full of dust, which would eventually spread throughout the ductwork. These new filters will clean the air and keep the ductwork clean.

Ductwork Inspection

The Bau-Biologie report recommended "periodic maintenance and cleaning" of the HVAC system and ductwork. I was a little hesitant about this after answering a question about duct cleaning and reading that the EPA says most homes probably don't need air duct cleaning and the cleaning may actually worsen indoor air quality.

But it made sense to me to at least get a professional inspection, especially since the system wasn't inspected when we moved into the house four years ago. I asked my Bau-Biologie friends for a referral, and was glad I did.

It turns out that there are two places where the outer jacket and insulation are damaged on the ductwork. Only the inner liner remains. The problem with this is that when the cold air runs through the duct in an attic that is over 100 degrees F, condensation forms. Dripping water can cause mold and ceiling damage. So this needs to be repaired.

The inspector also found that our air handler was very "rusty and dusty". He actually suggested that we replace it rather than clean it as it is more than twenty years old and of a design that was difficult to clean. Replacing it now would make it easier to maintain in the future.

The EPA report pointed out that because incoming air immediately goes through a filter before it goes through the duct, that little, if any, dust ends up in the ducts. Well, that wasn't true for us. As I said above, the duct right on the other side of the filter was very dusty. The EPA does recommend a high-efficiency filter, such as the new Filtrete filter we just installed, so if you want to minimize duct cleaning, that's good advice.

We will probably purchase a new air handler and then have the ducts repaired and cleaned after we have the mold removed. We don't want to take any chances with getting a proliferation of mold throughout the ducts. Better to spend a few hundred dollars now than thousands later.

Vacuum Cleaner

The next recommendation in the Bau-Biologie report was to get a new vacuum cleaner. We were using an old, old cannister vacuum cleaner that my husband got at some garage sale. Apparently, it has been found that the standard vacuum traps only about 30% of the dust collected, blowing the other 70% of the dust back in the room through the exhaust.

The report recommended purchasing a vaccum cleaner with a true HEPA filter to capture very fine dust, and to make sure that the vacumm case is also sealed at the seams. Miele vacuums are the only ones that were rated "totally effective" in a scientific study.

These vacuums are not inexpensive. The least expensive sealed true HEPA vacuum I could find was $350 and prices escalated to over $1000.

There are now many brands of sealed true HEPA vacuums, with many different features. After a good search around the Internet, I called Allergy Buyers Club and asked for their recommendation. Because I have hardwood floors and no carpet, they recommended the Miele Corinna cannister vacuum, which they sell for $395.

Continuing my search, I found State Vacuum, which advertises itself as "The World's Largest Vaccum Cleaner Store--The Vacuum Cleaner Experts For Over 57 Years!" And they were just a short drive across the bridge into Tampa! Ah ha! We could actually go see all the vacuums I had been reading about on the Internet, and they probably knew a thing or two about vacuums and could help us choose one. Well, they recommended the same Miele cannister vacuum, but with more bells and whistles for $599. They said it was simply the best for indoor air quality.

After checking out all the features on all the models, we chose the Luna model at $499--halfway between the stripped down Corinna and the highest-priced model.

We brought it home and the next day my husband vacuumed our house from top to bottom--even the furniture and the bed. We both noticed a HUGE difference and were very happy we made the purchase. Larry said, "I can breathe so much better now!"

Air Filters

The Bau-Biologie report also recommended a room-sized HEPA air filter. We decided not to get one, as we prefer fresh air and have our windows open as much as the weather allows. We felt changing the HVAC filter and using the HEPA vacuum would be sufficient.

Dust Mites

The Bau-Biologie report also had a few recommendations about controlling dust mites.

Dust mites are tiny bugs, closely related to spiders and ticks. They measure about 1/100th of an inch, so they are not visible to the naked eye. They live in beds (pillows, bedding, and mattresses), stuffed furniture, carpet, stuffed toys and old clothing. They love warm, humid places filled with dust. Dust mites feed on the dead skin that falls off the bodies of humans and animals and on other organic matter.

Dust mites are not actually harmful for most people, but they are a major component of the stuff that makes up the house dust that can cause allergic reactions. While the usual symptoms are respiratory (sneezing, itching, watery eyes, wheezing, etc.) other possible symptons include a red rash around the neck, eczema, headaches, fatigue and depression. If anyone in your household has any of these symptoms, the problem may be dust mites.

Because dust mites eat human skin cells and are present in most homes, the Bau-Biologie report recommended that we wash our bedding weekly in hot water and vacuum the mattress with a HEPA vacuum cleaner. Larry did vacuum our mattress with our new vacuum cleaner. We stopped sneezing.

LINKS

Environmental Protection Agency "The Inside Story: A Guide to Indoor Air Quality" -- Biological Contaminants

Greenpeace -- "Consuming Chemicals" Geochemistry of house dust, soil, and street dust in the city of Ottawa, Canada

Sick of Dust: New Report Finds Hazardous Chemicals in Household Dust

Debra's List - Air Filters