Rustic Precision Blog

The Basics of Indoor Air Quality Part I
The use of “green” building products and design stems from two concerns: concern for the impact of our activities on our environment, and concern for the impact our environment has on us. Increasingly, people recognize that contamination of the air we breathe in our homes has significant consequences for our health and quality of life. Quite literally, some people’s houses are making them ill.
Indoor air quality (IAQ) related-illness is increasingly common in homes, offices, and commercial buildings, it even has a name: Sick Building Syndrome. It could be that more people are sensitized to the responsible agents; it’s also likely that we’ve become more aware of IAQ problems and better at diagnosing them. Finally, it appears that the energy-efficient construction methods we now use with the toxic building materials we’ve always used, cause more problems now than in the past.

Causes of IAQ Problems
Many factors influence IAQ, but it boils down to the amount of toxins or pollutants either entering or released by your home, and its ability to dilute or remove them. How simple and cheap it is to address these problems? That’s very much a function of the specific problem itself, and the design and the siting (choice of specific location) of your home. This article lists some of the more common problems, their causes, and some solutions.

How do I know if I have Problems?
IAQ problems can have both immediate and longer-term effects. Short term, you may experience soreness of your eyes, nose, or throat; headache, dizzyness, or fatigue. If you occasionally suffer from asthma, you may experience more frequent or more severe attacks. If these symptoms appear at home – for example, overnight – and diminish or disappear altogether when you leave the house, you may have IAQ problems. Long-term, IAQ problems can lead to respiratory disease, heart disease, or cancer.

A Simple Test
Many people report the worst symptoms when they wake up in the morning, after their house has had a chance to “poison” them in their sleep. If this is true for you, and if the nighttime temperature outside isn’t too extreme, there’s a simple test you can try: put extra covers on your bed, and sleep with a window open. If you wake up feeling significantly better, there’s a good chance your house has air quality problems.

Inadequate Ventilation
A frequent cause of IAQ problems is inadequate ventilation. A steady influx of fresh air into your house should dilute toxins and contaminants that build-up with time. In an effort to make modern houses more energy efficient, we design them with air barriers to reduce the amount of exterior air that leaks into them and the amount of interior air that can escape. If the building envelope, as the conditioned (heated and/or cooled) space inside your house is called, is nearly air-tight, an entry point for fresh air has to be included in the home’s design.

Sometimes this fresh air vent is rendered inadequate by the addition of new combustion devices (for example, an electric stove or clothes dryer is replaced by a gas model), or the addition of new exhaust vents (e.g, a new bathroom fan or range hood.) Sometimes air intake filters for furnaces and air conditioning clog. (As you probably know, these should be changed regularly.) Sometimes the need for makeup air is not properly addressed in a house’s design. More commonly, remodeling increases these needs without addressing them.

In an effort to achieve acceptable IAQ while minimizing energy consumption, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cubic feet per minute (cfm) of outdoor air per person (20 cfm/person in office spaces). Up to 60 cfm/person may be required in some spaces (such as smoking lounges) depending on the activities that normally occur in that space (see ASHRAE Standard 62-1989). There is considerable debate as to how much airflow is enough. Regardless, measuring your home’s ventilation rate requires special equipment. HVAC and home performance specialists can do this for you.

“How can I possibly heat or cool my home with all this air blowing through it?” you might well ask. Actually, adequate ventilation should – and can – be achieved in energy efficient homes in all climates. In climates with extreme cold, heat recovery ventilation (HRV) systems extract the heat from warm outgoing air and use it to warm incoming cold air. In hot climates, energy recovery ventilation (ERV) systems do the opposite: chill hot incoming air with cool, outgoing air.

The following sources provide additional information:
ashrae
Home Ventilation Options
Home Ventilating Institute

Had Enough of Your Convertible?
If all this air blasting through your home is an uncomfortable thought, and you are either willing to undertake major renovations or are considering building a new house, take heart: there are great alternatives. Common in much of Europe, radiant heating and cooling systems heat building interiors rather than the air in them. When combined with low-velocity fresh air distribution systems, radiant heating and cooling provide an efficient, comfortable solution, even in the most extreme climates. As they are only recently becoming popular in the U.S., you won’t find information on these systems in the above references. These systems are often integral to the design of zero-energy homes.

Sites selling radiant heat systems abound. However, for commercial-free background on radiant heating systems, see:
Wikipedia Passive House
Wikipedia Radiant Heating

If you’re interested, I’ve written another article on wall systems and construction methods designed to eliminate forced air HVAC:
Ideal Wall

Combustion By-products
Surely indoor air quality has improved drastically since our ancestors heated and cooked with open fires in their caves. Nevertheless, the by-products of combustion – including carbon monoxide – represent some of the more dangerous IAQ problems. To protect occupants from combustion gases, building codes require the majority of combustion appliances be direct or power-vented to the outdoors. Unfortunately, none of these appliances works as intended without sufficient fresh, outside air (makeup air.)

Power venting appliances mostly ensures that the by-products of combustion from the appliances in question end-up outdoors, but it can have the unintended effect of pulling in air from somewhere it shouldn’t. For example, a power vented furnace can pull smoke out of a fireplace. The furnace wants fresh air; it will get it by pulling it down the chimney if it has to.

If you experience headaches, dizzyness, burning eyes, nose or throat, and particularly if you can correlate these problems to the operation of a particular combustion appliance in your home, the first step (after attempting the “open window” test described earlier, if practical) is to make a series of simple inspections.

Check each appliance to see that the flue is properly connected and isn’t blocked (by the nests or corpses of dead inspects, birds or rodents.) If you don’t find anything that simple, try the “match” test on each combination of appliances: use a lit match to indicate which direction air is flowing through the device. For the power-vented furnace/fireplace example, turn the thermosat up to make sure the furnace starts, and with no fire in the fireplace and the damper open, light a match inside the fireplace. The match flame should stretch upward, indicating a strong updraft in the chimney. If it stretches toward you, or is blown out, you know you have a problem. Note: for gas appliances, if there is any possibility you have a gas leak, don’t use a match or other flame!

VOCs and Off-gassing
A surprising number of everyday products in our homes contain toxic volatile organic compounds (VOCs). Linked to short and long-term disease as minor as headaches and as serious as death, these compounds include petroleum-derived solvents, household cleaners like chlorine bleach and ammonia, and some natural solvents like citrus solvent (“orange oil”). They’re found in vinyl products (e.g, flooring, windows), carpet, paint, cabinets, counter tops, window drapes, air fresheners and many others. Typically, the products off-gas this nasty stuff most when brand-new, and do so less over time. Of those used widely in common building materials, urea-formaldehyde is one of the worst. Found in plywood, particleboard, medium density fiber board (MDF), laminate counter tops and other pressed wood products, it releases toxic gas somewhat uniformly throughout its life. Products that use phenol-formaldehyde are better. My understanding is that they off-gas a great deal during manufacture, and relatively little thereafter. One small piece of good news is that many of these products, like vinyl and air fresheners, stink, making them easier to identify.

During renovations, consider wood-clad fiberglass or aluminum windows over vinyl. Choose low- or no- VOC paints, cabinets, furniture, and counters. Ask that countertops be installed with low VOC adhesives. Ditto for caulks and other sealants. Look for low-VOC carpet or consider natural rugs and/or wood, linoleum, cork, or bamboo flooring products. Avoid fabrics that have permanent press treatments.

Another source of VOCs are chemicals that people intentionally bring into their homes and apply: cleaners, polishes, paints, lacquers, perfumes, etc. Consider using less toxic products for the same purposes.

The Attached Garage
The automobile is an explosive device filled with toxic chemicals—oil, gasoline, antifreeze, brake fluid, and refrigerant, to name a couple. As if that weren’t enough, it’s also a massive, air-consuming combustion device when it runs. The gas-powered tools and usual array of chemicals people store in their garages are worse. Building codes require that the wall(s) and door(s) shared between a house and a garage be fire-rated for these reasons.

If air can move between your garage and house, toxic VOCs can move with it. At the very least, they will follow you in through your garage entry door. If you have living space above your garage, the chances of carbon monoxide and other auto exhaust components getting into your house by convective means, through your floor, are pretty good.

Make sure your garage is well-sealed from your home. For a standard attached garage, the air barrier in shared wall(s) should extend floor to roof, not just floor to ceiling. Weather stripping and an airtight seal around the doors, which code requires to be self-closing for fire safety, are a must. Avoid idling vehicles in your garage – start, gingerly back out, close the door, and then finish your warm-up.

If you live over your garage and can smell it, seal gaps and cracks with spray foam. Pay particular attention around penetrations for wires and pipes.

Smoke
Tobacco and other types of smoke contains creosote, formaldehyde, and other good stuff, all of which are carcinogens and can get trapped and re-released from carpets, drapes, bedding, etc. If you are a smoking household, you’d be wise to limit it to the garage or outdoors.

Radon
Radon is a radioactive gas released from uranium that can accumulate beneath your house and enter it. You don’t have to live near a nuclear power plant or waste storage facility for this to be a problem: uranium ores are found naturally in many soils, particularly in some types of granite. A Geiger counter (radiation meter) detects the problem. If you have a crawlspace, the solution is usually to seal it and/or install vent stacks similar to the vent pipes on your roof that vent your plumbing fixtures. Radon gas then dissipates above your roof instead of entering your house.

Outdoor Contaminants
If you live near a busy street, your house can become contaminated by particulate of brake linings, soot, and other auto combustion byproducts. Depending on where you live, you may also get herbicides, pesticides and bacteria. If you suffer from hayfever, pollen is also a concern. If your house is well-sealed, you may still transport these contaminants into your house on your shoes and in your clothes.

If the air quality in your area is bad enough, you should use a 24/7, whole-house ventilation system to filter all your incoming air. Avoid opening windows on bad air days.

If you don’t have one, consider creating a “mud area” and removing your shoes there before advancing further into your home. Shoe removal is widely practiced outside the US. Besides improving your health, you may be astounded at how much longer your house stays clean.

Lead
Lead-based paint is hard-wearing and very good at protecting surfaces. Unfortunately, lead is extremely toxic. Lead paint was banned for residential use in the U.S. in 1978. Any paint applied prior to that date should be suspect until tested. Home lead test kits are available, but not reliable. Best is to collect an appropriate sample and send it to a lab.

Remediation methods include painting over the lead paint, and removing it. Removal requires significant safety precautions, since the risk of lead poisoning is greatly elevated until all the paint is gone. Don’t attempt it yourself; hire professionals.

Other countries have not been so quick to ban lead in paint. Imported children’s toys may be painted with led paint. Inexpensive jewelry may contain significant quantities of lead.

Sources and additional information:
Lead Paint info at Wikipedia
Lead info from EPA

Asbestos
Once regarded as a miracle flame-retardant additive, asbestos was once used in everything from construction materials to children’s pajamas. Exposure to airborn asbestos fibers, even short-term, can be harmful or deadly. Risk is proportional to exposure: the greater the concentration and/or the longer the time of exposure, the greater the harm. Once airborn, asbestos fibers enter and damage the lungs.

The U.S. instituted a ban and phase-out of asbestos in 1989, which then became a partial ban in 1991. Asbestos is particularly prevalent in building materials. Some types of building materials are still manufactured in the U.S. with asbestos. Other products containing asbestos are manufactured elsewhere and imported to the U.S. Just to give you an idea, products that can contain asbestos include: sprayed-on insulation (acoustical, thermal, decorative, etc), sheetrock patching or taping compound, insulation around heat sources (e.g., stoves and fireplaces), electrical insulation, pipe coverings, vinyl sheet flooring (backing), roofing and siding, fireproof curtains.

Sources and additional information:
Asbestos info from the EPA and Asbestos info from Wikipedia

More Resources
For more information on IAQ Problems, see the US EPA website: IAQ info from the EPA