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Indoor Air Quality - What It's All About

By HHI Staff

This article will discuss what’s in the indoor atmosphere of most homes. As you will see, “air” is composed of far more than just oxygen, nitrogen, and carbon dioxide. People assume that the air they breathe in their homes is safe and healthy. Unfortunately, that isn’t often the case.

Government Regulations

While it’s true that the air outdoors has steadily improved because of the passage and enforcement of various anti-pollution regulations over the years, the quality of the air indoors has steadily decreased because it’s been largely ignored. In fact, no government agency—not even the EPA (U.S. Environmental Protection Agency)—has minimum regulatory standards. In fact, in most locales, there are no minimum indoor air quality standards at all.

 

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One bright spot is the banning of smoking tobacco within many buildings. However, air-quality regulations specifically applied to houses, including smoking, are almost non-existent—but not quite. For example, a few countries (Canada is one) now require a basic ventilation system, to bring fresh air into a house and to expel stale air, to be incorporated into new houses. But, other than that, there are very few indoor-air-related regulations.

Since the “energy crunch” back in the 1970’s, many builders have striven to build homes more tightly in order to lessen the air exchange that once commonly occurred around doors and windows, etc. Unfortunately, they’ve generally not incorporated whole-house mechanical ventilation systems as an alternative to providing fresh air. Even if there is some level of ventilation (planned or unplanned) within a home, if the living space is filled with synthetic air fresheners, polluting cleaning products and decorating items, etc., the ventilation rate may not be enough to make the indoor air truly healthy. As a result, the sad truth is that most of us inhale a tremendous number and variety of pollutants whenever we’re indoors. One well-reported estimate is that the air quality inside an average house is at least five times worse than the air quality outdoors—even in major cities—and sometimes indoor air is even more polluted.

 

By the way, if you’re interested in a complete discussion of home ventilation, including the simple physics of air movement, planned and unplanned methods of air exchange, problems, equipment, and more, read Understanding Ventilation by John Bower. This informative book can ordered from used booksellers.

Indoor Air Quality Defined

So, exactly what is indoor air pollution? Defined, indoor air pollution is the presence of substances (either gases or particulates) within a home’s atmosphere that could negatively affect human health (or the health of your pets). These pollutants might be natural materials (pollen, for example) or derived from man-made substances (the outgassing of synthetic materials). The duration of air pollutants can be brief, but intense, as when you use model-airplane glue, or long-term and chronic at a lower level, as with the release of combustion by-products from your gas range’s burning pilot light.

 

Ideally, the best defense against indoor pollution is not owning or using any potentially contaminating materials or products inside your home. This should be combined with thorough and regular house cleaning using less-toxic, low-odor products, controlling any serious moisture problems in your home (including high relative humidity), and providing your house with adequate fresh-air ventilation. At this point, if your home still has somewhat minor air-quality problems, using an appropriate air-cleaning device (i.e. an air filter) can be helpful to remove most of the remaining airborne contaminants.

 

Admittedly, seriously reducing existing air pollution levels in your house can sometimes be difficult. However, if you address the individual air-pollution sources one by one, it’s likely you’ll eventually have indoor air that will positively, rather than negatively, affect the health of you and your family.

 

In addition, if you have more questions on indoor air quality, you may want to call the EPA Indoor Air Quality InfoLine sponsored by the EPA (Environmental Protection Agency). There, specialists are available to answer many of your questions, and you can request pertinent publications be sent to you at little or no cost. You can also request publications directly from the EPA National Service Center for Environmental Publications.

Indoor Air Pollution Testing in General

As you read the sections on specific indoor pollutants below, routine testing (or monitoring) procedures for several of them are given. It should be said that there are environmental testing companies that can do on-site measuring for virtually all the contaminants listed. There are also home test kits you can buy for yourself.

 

Because tests and testing companies have now become available, it’s not surprising that many people ask, “Should I have my house tested for mold (or formaldehyde or whatever)?” In the end, that’s a decision you must decide for yourself. The truth is, there are certain tests you can perform on your indoor air that are simple, low-cost, and they can give you truly valuable information—for example, radon tests. However, there are other tests that can be less worthwhile to you. And any test, even a useful one, will only be able to give a reading based on the limited time frame during which the actual monitoring occurred. Therefore, the results could give you a false sense of safety.

 

It should be understood that the accuracy and usefulness of an indoor pollution test will depend on it’s proper setup, the sensitivity of the measuring device, the correct analysis of the recorded data, and your (or an expert’s) knowledge on how to interpret the results, to effectively solve any problems. After all, tests generally can’t tell you the actual source(s) of the contaminants they’ve measured. By the way, it’s not unusual for very sensitive persons to find that they react negatively to air-pollutant levels that are considered safe by conventionally performed tests. This is often because these individuals are far more susceptible to lower concentrations of particular pollutants than average populations, that their systems are more sensitive than the mechanical devices doing the testing, or that they are reacting to contaminants not even being tested for. Therefore, sometimes a sensitive person’s nose can better determine, more accurately, for him- or herself if a problem is present (and at a lower cost) than air-quality testing.

 

You should be aware that the cost of having your indoor air tested will vary, depending on who does the testing, the extent of the testing, the degree of test sensitivity, and exactly what’s being tested for, among other factors. Therefore, before you decide to hire an environmental testing company, find out how long they’ve been in business, whether they have any certification or licenses, some professional references, how soon you can expect to have a written report, and what the final costs will be. Incidentally, you might ask your local board of health for a company they would recommend.


Specific Indoor Air Pollutants

 

The following sections discuss some of the more common indoor pollutants. You’ll find that they’re classified in several major categories.

 

 

Gases

 

As you might suspect, potentially harmful gases can make up a certain proportion of a home’s indoor air pollution. The following sections discuss some of the more common of these.

 

 

Combustion Gases

 

Combustion gases are the invisible gases resulting from combustion (the burning of a substance). Smoke, which consists of tiny particles and vapors (the visible components of combustion) may also be released when materials are burned. In homes, combustion gases are created from combustion appliances such as gas and oil furnaces, gas dryers, gas water heaters, and gas and oil boilers. Others sources include fireplaces, wood stoves, tobacco, kerosene lamps, and even candles.

 

The combustion of fuels can also produce water vapor, carbon monoxide, carbon dioxide, sulfur dioxide, formaldehyde, and other gaseous hydrocarbons. Unfortunately, breathing combustion gases can lead to respiratory problems. While it isn’t healthy to breathe any combustion gases, carbon monoxide (CO) is, by far, the most life-threatening.

 

Keeping your combustion appliances properly maintained and adjusted, ensuring that the chimney functions correctly, and having adequate fresh-air ventilation, can all help reduce the levels of combustion gases indoors. However, when you burn a fuel indoors, it’s often difficult to completely eliminate combustion gases from the living space. (Generally, combustion gases are expelled through a chimney, but not all chimneys function correctly. As a result, in many houses, some, or all, of the combustion by-products remain inside the living space.)

 

To completely eliminate any concern over combustion gases existing in your home’s air, it may be necessary to stop burning all substances indoors. While many people would find this difficult, for some very tightly constructed, underventilated homes, or for certain very sensitive or acutely asthmatic individuals, this approach might be necessary. Another less dramatic solution involves using a high-efficiency gas or oil furnace having a sealed combustion chamber. These devices do not require a conventional chimney. Instead, they use a fan to blow the combustion gases outdoors through a sealed exhaust pipe.

 

 

Carbon Monoxide

 

The most serious combustion gas in houses is carbon monoxide (CO), a flammable, odorless, tasteless, colorless gas. It’s typically formed as the result of the incomplete combustion of carbon-containing fuels. In homes, high levels of CO can be released from fireplaces (either using wood or natural gas for fuel), coal- or wood-burning stoves; or from kerosene, oil, propane, and natural-gas space heaters, furnaces, hot water heaters, or other combustion equipment. Whenever you burn something, various combustion by-products, such as smoke, carbon dioxide (CO2), water vapor, and CO, are released. The thing that makes CO so dangerous is that, when it is breathed into the lungs, it immediately reacts with hemoglobin (red corpuscle proteins) in the blood. Once saturated with CO, the hemoglobin can no longer perform the essential function of transporting life-sustaining oxygen throughout the body.

 

Commonly, one of the first signs of CO poisoning is a headache. As more CO is inhaled, flu-like symptoms follow, such as muscle weakness, loss of coordination, confusion, and unconsciousness. Death will occur if levels of CO in the blood become high enough. Eerily, light-skinned victims of severe CO poisoning take on a characteristic cherry-red coloring. Each year in this country, hundreds of people die from unplanned, undetected, high carbon monoxide concentrations in their homes, and many more suffer symptoms that they attribute to the flu when, in fact, they are being poisoned by CO. The sad truth is that CO poisoning is the number one cause of accidental poisoning in the U.S., with 10,000 people experiencing some level of poisoning annually—whether they know it or not.

 

Not surprisingly then, some experts believe that ideal healthy houses shouldn’t have any forms of combustion taking place inside the living space. However, if your home does have some type of combustion device, it is absolutely essential that it be working efficiently. Fortunately, when a gas-burning appliance is properly adjusted, CO production is minimized. Therefore, make sure your combustion equipment (and chimney) has a professional checkup and necessary maintenance annually. If, for any reason, carbon monoxide poisoning is suspected, get out of the house immediately. Then, don’t return until a professional has inspected and repaired any malfunctioning equipment.

 

It’s also a very good idea to install one or more carbon monoxide detectors. (A few local jurisdictions now require at least one in all homes.) The Consumer Product Safely Commission has recommended placing one near your home’s sleeping area, with extra alarms on every other level in your house. These devices will continually monitor CO levels in the indoor atmosphere. When a higher-than-normal CO concentration is detected, an alarm will sound. Like smoke detectors, some CO detectors are battery-operated, while others are designed to be wired into your home’s electrical system. A few newer models combine both smoke and CO detecting in a single unit, some have other features such as a voice warning. If you’re interested in purchasing a CO detector, they’re usually handled by local hardware stores.

 

If you purchase a CO detector, you should test it weekly. You can do this by simply pressing the test/reset button with your finger or with the end of a broom handle if you can’t reach it. Also, if it’s a battery-run model, replace the batteries twice a year. One final note: If you don’t own any combustion appliances but do burn candles or oil lamps occasionally, installing a CO detector a still good idea. With the popular craze underway for burning a dozen or more of candles at a time, CO can unknowingly build up, even from such small combustion-gas-generating items.

 

 

Carbon Dioxide

 

Carbon dioxide (CO2) is a tasteless, colorless gas. It’s created through the action of human and animal respiration, decay, and the burning of organic materials. Although it’s always present in the air (it typically makes up 0.03% of outdoor air), high CO2 levels in homes usually indicate that there isn’t enough fresh air indoors. Although CO2 isn’t particularly toxic itself, too much of it can lead to an uncomfortable feeling of stuffiness or closeness, which can add stress to those already having respiratory problems. If fresh air is brought into such a home, the carbon dioxide levels will be diluted and rapidly diminish, and the stuffy sensation would soon go away.

 

Unfortunately, a high carbon dioxide level in houses is a growing problem. These days, some new homes are so tightly built that air can’t infiltrate (find its way indoors). This often leads to an environment in which there is little fresh air in the house—simply because no planned ventilation system was ever installed. For a more in-depth discussion of residential ventilation, and ways to accomplish it, you may want to read Understanding Ventilation by John Bower.

 

 

Volatile Organic Compounds (VOCs)

 

Volatile organic compounds (VOCs) have become a serious health threat in many homes. This section explains what these chemicals are, why some are harmful, and how to prevent them from becoming a problem in your home.

 

 

The Nature, Uses, and Potential Health Consequences of VOCs

 

Volatile organic compounds are actually a class of carbon-based chemicals that have the capacity to rapidly evaporate. Once airborne, many VOCs have the ability to combine with each other (or with certain other molecules in the air) to create new chemical compounds.

 

In reality, a great many different compounds are classified as VOCs. Some are of natural origin and happen to be relatively benign. For example, a freshly cut orange or onion both give off certain types of VOCs. However, there are also naturally occurring VOCs that can be extremely dangerous such as the toxic VOCs given off by certain molds. Other VOCs, such as alcohol, lie somewhere in between.

 

Usually, however, when the term VOC is used in conjunction with indoor air quality, it doesn’t refer to naturally occurring VOCs. Instead, it generally refers to VOCs derived from man-made manufactured products, such as the common solvents toluene, xylene, and lacquer thinner. Other synthetically derived VOCs routinely found indoors include formaldehyde and benzene.

 

Although the negative health effects on humans, from synthetically created VOCs, varies with the particular compound, as a rule they can be harmful to breathe. Many are inflammatory to mucous membranes and the respiratory system. The worst VOCs have been linked to central-nervous-system damage, chromosomal abnormalities, and even cancer. Interestingly, many sensitive individuals feel that exposure to certain dangerous VOCs is the reason for the onset of their Multiple Chemical Sensitivity (MCS). VOCs can also trigger asthma attacks in susceptible persons.

 

Unfortunately, today, potentially harmful VOCs are found in the indoor air of many U.S. homes. In some homes they exist at fairly high levels. This is because many typical finishes and coatings (including wall paints), adhesives, cleaning products, man-made wood products (including particleboard, plywood, wall paneling, and cabinets), as well as other synthetic materials, contain and release some of these compounds. For the most part, the quantity of VOCs in common consumer products and materials is poorly regulated. However, in 1987, California began regulating the VOC content of paint, and other local jurisdictions have since passed similar restrictions.

 

 

Testing and Eliminating VOCs in Homes

 

If you want to determine the amount of volatile organic compounds (VOCs) in your home, an environmental testing company can be hired to come in and make measurements. But comprehensive testing can cost hundreds of dollars and could easily result in a list of a hundred or more different VOCs in the air. While relatively inexpensive test kits are available, it’s unlikely that such simple, inexpensive tests will be very helpful. Even a sophisticated test, listing scores of specific VOCs and their concentrations, probably wouldn’t be much help either. After all, you still wouldn’t know the sources releasing the specific chemicals.

 

So, how can you know if the VOC level is too high? The truth is, when it comes to VOC levels in the indoor air, it’s impossible to precisely predict at what concentrations you or your family will become affected. Some people are just more susceptible than others. Therefore, the best defense against the dangers of breathing VOCs is to only use items with minimal amounts of VOCs in them, or none at all.

 

It should be noted that newly applied paints and finishes will quickly give off their own distinctive VOCs. But older items, that emitted high levels of VOCs when they were new, will eventually release lower and lower amounts of these gases. This is because, by their very nature, VOCs evaporate quickly. Any level can be diluted with good indoor ventilation.

 

Furthermore, activated charcoal can be effective in adsorbing VOCs that have higher molecular weights. (Molecular weight is defined as the total atomic weights of all the component atoms making up a molecule. Larger, more complicated molecules are made up of many atoms, so they tend to have high molecular weights.) For low-molecular weight VOCs, such as formaldehyde, specially treated activated-charcoal or activated-alumina can be effective. In addition, some types of zeolite may be helpful as well. However, for certain sensitive individuals, ventilation and/or filters may not be enough to stop reactions if VOC-releasing materials remain within their homes. That is because filters and ventilation can only reduce levels, they can’t eliminate VOCs completely.

Formaldehyde

These days, one of the most common VOCs found in the indoor air is formaldehyde. It’s presence can provoke a variety of health complaints, some of them chronic in nature. The following sections discuss this well-known contaminant, and what you can do to reduce it’s level in your home.

 

 

The Nature, Uses, and Health Consequences of Formaldehyde

 

Formaldehyde (HCHO) is the simplest chemical in a class of organic compounds known as aldehydes. (All aldehydes contain the CHO group of atoms.) Formaldehyde is considered a volatile organic compound or VOC. At very high concentrations, formaldehyde is an extremely reactive, colorless gas with a distinctively pungent and unpleasant odor, however, at concentrations typically found in houses, it’s virtually odorless.

 

If formaldehyde is inhaled, it can cause nasal and sinus irritation, respiratory inflammation, asthma, depression, and even menstrual irregularities. Formaldehyde exposure can also cause burning eyes, and has been shown to be mutagenic (capable of increasing the rate of cellular mutations) and carcinogenic (cancer-causing). After becoming sensitized to formaldehyde, a certain percentage of the population (probably less than 10%) has been shown to react to smaller and smaller amounts of it. Interestingly, exposure to formaldehyde has been reported by many individuals with Multiple Chemical Sensitivity (MCS) as a suspected cause of their illness. Virtually all people with MCS react negatively to extremely low concentrations of it.

 

Formaldehyde is one chemical that’s both exceptionally easy and inexpensive to produce. It’s also one that can be used in a myriad of applications. Therefore, in the last few decades, it’s been routinely utilized in a wide range of consumer products. One use that received a lot of public attention was in urea-formaldehyde foam insulation, a material that was popular in the 1970s, then was banned because it released a great deal of formaldehyde. Today, it is no longer banned but, because of bad publicity, it is rarely being used. The urea formaldehyde (UF) resin in this particular product can emit relatively high levels of formaldehyde over several years. But formaldehyde is also found in the glues and resins used in a variety of man-made wood products, either as urea formaldehyde or phenol formaldehyde (PF). PF glues emit considerably less formaldehyde than UF glues.

 

Formaldehyde is also used in some clear finishes. For example, UF finishes are typically used on kitchen cabinets. It’s also commonly used as a resin treatment on certain fabrics to give them wrinkle resistance—for example, to create no-iron sheets. In addition, formaldehyde is used in the manufacturing of some paper goods, such as paper towels, to increase absorbency. Besides these particular applications, it’s sometimes used in personal-care products, cosmetics, shampoos, even toothpastes. Unfortunately, most of the items containing formaldehyde will release it into the air. In the case of cabinets made with formaldehyde-containing glues and finishes, the formaldehyde will continually be released for years. In fact, the formaldehyde in some man-made wood products has a half-life of 3 to 5 years. This means that during the first 3 to 5 years, half of the formaldehyde present will be released. During the next 3 to 5 years, half of what remains is outgassed, and so on. Interestingly, the amount of water vapor present in your home, as well as the temperature, will affect the rate of formaldehyde release. Both a higher relative humidity and higher temperatures will cause the formaldehyde to be emitted into the air faster.

 

 

Testing and Eliminating Formaldehyde in Homes

 

What is considered an acceptable, safe, level of formaldehyde in the indoor air is still being debated. However, increasing numbers of concerned experts believe that formaldehyde concentrations should be as low as possible in the air you breathe. So, how much formaldehyde is too much? Clean outdoor air in the country might contain 0.01 parts per million (ppm). Sensitive people often react to levels as low as 0.03 ppm, and levels of 0.05-0.15 aren’t unusual in houses. The World Health Organization recommended a few years back that levels be below 0.05 ppm in homes. This is especially important if a house contains young children, asthmatics, or persons weakened by a major illness. On the other hand, levels as high as 0.75 ppm are often allowed in the workplace.

 

Because of the controversy over the safety of formaldehyde, some people feel it is a good idea to test their home’s formaldehyde level. If you’d like to have this done, contact an environmental-testing company or buy a home formaldehyde test kit. Unfortunately, testing may not detect the extremely minute levels that still promote reactions in certain sensitive individuals. And these tests can’t pinpoint the outgassing source(s) of the formaldehyde for you.

 

If your home has too much formaldehyde, what can you do? Airing items outdoors that are suspected of containing high levels OF formaldehyde (such as some new furniture) for a period of time can often help. Special sealant coatings can be applied to wood items such as kitchen cabinets and to carpeting. However, for many chemically sensitive individuals, these remedies just don’t seem to help enough. So, after airing and sealing, some of your home decor may still remain too bothersome. By the way, certain types of sealants will pollute the air themselves (at least for some time after they’re initially applied) with their own chemical odors.

 

As you might suspect, some air filters can remove formaldehyde from the air. Activated charcoal is often used but, in reality, it is not particularly useful unless it has been specially treated. This is because typical activated charcoal can’t effectively adsorb low-molecular weight VOCs such as the fairly simple formaldehyde molecule. (Commonly, molecular weight is defined as the total atomic weights of all the atoms making up a molecule.) However, activated alumina can remove a great deal of airborne formaldehyde, and certain zeolites may be helpful, too. Yet, even these filtering media are often not sufficient for very sensitive people.

 

The truth is, permanently removing the source of the formaldehyde, or storing the offending items elsewhere until the amount of formaldehyde they release is undetectable, are the two best solutions. Of course, this can be disruptive, time-consuming, and costly. However, these are the only measures that will best ensure your family’s health from exposure to formaldehyde.

Radon

Within the last few decades, researchers have become aware that radon gas is present in quite a few American homes at unacceptably high levels. Unfortunately, they have also concluded that the presence of radon at high concentrations can lead to serious health consequences. The following sections discuss exactly what radon is, how to detect it, and ways to reduce it.

 

 

The Nature and Potential Health Consequences of Radon

Radon (Rn) is an odorless, colorless, radioactive gas. Actually, there are twenty radon isotopes (unique atomic forms each having a different number of neutrons). Of these, radon-222, which is produced by naturally occurring radium in the soil, is the isotope of most concern. It’s radon-222 that can cause serious health problems if it becomes concentrated in your home.

 

Radon-222 can enter houses through foundation cracks and/or through well water. If it’s unable to leave freely (for example, through a ventilation system), it’s concentration soon rises. Unfortunately, the trapped gaseous radon-222 goes through a natural radioactive decay process, producing radon decay products which are solids. It’s these decay products (often chauvinistically called radon daughters)—and not the radon gas itself—that can become lodged in your lung tissue and eventually lead to lung cancer. Because of this, radon is believed to be the Number Two cause of lung cancer in the U.S. (Smoking remains Number One.)

 

It should be pointed out that radon gas is a natural part of our environment. In fact, it’s been estimated that it makes up more than half of the background radioactivity we are surrounded with every day because it’s continually rising up from bedrock, soil, and from some ground water. However, because of certain geologic conditions, some locales have much higher concentrations of radon than others. In the U.S., for example, there are radon “hot spots” in western Pennsylvania and Maryland, as well as in other locals. If done correctly, proper sealing measures can prevent radon from entering most homes. But, in the cases of some tightly built houses, while the radon may be entering at a low rate, it may also be leaving at a low rate, thus exposing the people living in the house to unhealthy levels.

 

 

Testing and Eliminating Radon in Homes

 

It’s important for every home to be tested for radon. Because of individual differences in construction and in soil conditions, there’s absolutely no way to guess whether or not a specific house will have a high radon level. Even if all your neighbors’ homes have low levels of radon, yours might have a high concentration. But what exactly is a high radon level? Currently, the EPA (Environmental Protection Agency) says that any reading above 4 pC/l (4 picoCuries of radon per liter of air) should be cause for concern.

 

To determine if your home falls above this level, you can buy a simple radon test kit. These are relatively inexpensive and are available at most local hardware stores and building centers. Radon test kits are really very easy to use. Most are made so that, after reading the instructions, you open the sampling container (usually a small canister), place it in a suggested location, and leave it there undisturbed for the recommended time. Then, you seal the container, fill out a simple form, and mail it to a laboratory. The test results are then mailed back to you. (Incidentally, it’s possible to buy continuously operating radon-gas monitors, if you feel that’s necessary.)

 

If an inexpensive radon test indicates a level above 4 pC/l, you’ll probably want to buy a costlier, more sensitive test kit—or have an environmental testing company perform a more accurate test for you. If the result of the second test is also high, radon-control measures (known as radon mitigation) should seriously be considered to reduce the concentration.

 

Ridding your house of high radon levels entails either some form of ventilation system to safely direct the radon toward the outdoors, or sealing any cracks in the foundation and basement floor to prevent the radon from entering, or both. There are also other approaches, and no single mitigation measure is appropriate for all houses. To help you know precisely what to do, your local board of health may be able to provide information on radon tests, radon-reduction strategies, and perhaps even the names of local companies that specialize in radon-mitigation services. In addition, a number of books have been published about radon. One you might read is Radon: A Homeowner’s Guide to Detection and Control by Bernard Cohen and the editors of Consumer Reports. Although this particular book is no longer in print, it (and other good books on radon) may be available from your local library. For still other books, check with your favorite booksellers. Also, it would be a good idea to contact the EPA National Service Center for Environmental Publications, or the EPA Indoor Air Quality InfoLine, to order their free radon booklets. An InfoLine specialist may be able to personally supply you with some of the answers for which you’re looking.

Vapors

A vapor is a gaseous substance that is usually a liquid at room temperature. As you might suspect, the most common vapor in houses is water vapor. If too much is present, high relative humidity results.

 

High relative humidity exists in many houses. Unfortunately, this can lead to a host of possible problems. The sections below explain relative humidity, and ways you might lower it, if necessary, in your home.

 

 

High Relative Humidity Defined and Potential Consequences

 

Humidity refers to the water-vapor content of air. Because there is always some moisture in the air, it can be difficult to think of humidity as a pollutant. Yet, if your indoor air contains high levels of water vapor, it can damage your walls, floors, and interior furnishings. Also, high water-vapor levels can result in mold, mildew, and other microbial growth. In addition, it can often increase the rate of formaldehyde release from man-made wood products, etc.

 

The word relative is used with humidity because there’s a direct relationship between the temperature of the air, and the potential amount of water vapor the air can hold. Simply put, cold air can’t hold as much water vapor as warm air. Therefore, if a room at 50°F held 10 gallons water vapor, and an identical room at 80°F also held 10 gallons of water vapor, the rooms would have the different relative humidities. The warmer room would have a lower relative humidity than the cold room because warm air has the potential to hold much more water vapor than cold air. Incidentally, when air at any temperature is saturated and is no longer capable of holding any more water vapor, it’s said to have a relative humidity of 100%. At the usual indoor temperatures of American homes, the best relative humidity would be 40% or less in the winter. At 40% relative humidity, there’s still enough moisture present in the air so mucous membranes usually won’t become irritated, the skin won’t become dried out, wood won’t tend to crack, and yet 40% is usually too low for mold and mildew to thrive.

 

With the use of an instrument called a hygrometer, you can easily measure the relative humidity in different locations in your home. These devices are usually sold at hardware stores, building centers, and at department stores.

 

Reducing High Humidity in Homes

If your home’s air regularly has high relative-humidity readings, check for water sources around your house. These could include leaking air conditioners and plumbing lines, or damaged roofs. Also look for clogged gutters and foundation drains. In addition, too much shady foliage planted near the house can contribute to problems.

 

Of course, poor ventilation can easily result in high indoor humidity levels. Therefore, it’s a good idea for rooms in your home that commonly generate large amounts of water vapor to be properly vented to the outdoors, so the water vapor can’t build up indoors. Ideally, a range hood over your kitchen stovetop, an exhaust fan in your laundry room, and exhaust fans in your bathrooms, should be installed and used regularly. All such fans must be vented to the outdoors to be effective.

 

Bathroom fans can have a simple, manually operated on/off wall-mounted switch, a manually set crank timer, or they can be controlled by a dehumidistat. A dehumidistat is simply a device that monitors relative-humidity levels. It can be used to automatically turn on an exhaust fan when a certain relative humidity is sensed. For example, a dehumidistat could turn on a bathroom exhaust fan when the relative humidity rises after a shower. You’ll also want to make sure that your clothes dryer is vented to the outdoors.

 

You can also lower the relative humidity by using air conditioners and dehumidifiers. Both pull water vapor out of the air and condense it into liquid water. Of course, air conditioners and dehumidifiers are available from many local department and appliance stores.

 

It should be noted that dehumidifiers can be emptied either automatically into a house drain, or manually. If you decide upon a dehumidifier, it’s important to clean it regularly to prevent any mold growth. This is especially necessary with models that must be emptied manually inasmuch as they can contain standing water for some time.

 

In the winter, closets can have a higher relative humidity than other rooms in a house, so they can also be places where mold can grow.

 

 

Biological Contaminants

 

Anything airborne that is now living, was once living, or was produced by something alive, and has the capacity to create negative health effects, is considered to be a biological contaminant. Therefore, bacteria, viruses, dust-mite body fragments and feces, mold, mildew, and pollen are all biological contaminants. These particular biological contaminants are in particulate form (tiny bits of solid matter). However, most metabolic processes also release a variety of gases including volatile organic compounds (VOCs). These, too, are biological contaminants, but in a non-particulate, gaseous form. Some of the most common biological contaminants found in homes are discussed below.

Bacteria and Viruses

In America, bacteria and viruses are popularly known as germs—a word with very negative connotations. Surprisingly though, many bacteria and viruses are not harmful to human beings. In fact, many bacteria are actually necessary for life. But, of course, there are also harmful, disease-causing bacteria and viruses in a home’s air whose numbers should be minimized, or eliminated, if at all possible. Following is information on both viruses and bacteria, and suggestions regarding methods you might try to control their populations within your own home.

 

 

Bacteria

 

Bacteria is a classification of some of the 'simplest' single-celled microscopic organisms on earth. Unlike viruses (see Viruses below), individual bacteria are complete entities in themselves and are capable of their own reproduction. In size, bacteria usually range from 0.2–50 microns in length (One micron is one millionth of a meter, a very fine human hair is about 40 microns in diameter.) So far, about two thousand species of bacteria have been identified, and they have been found to exist virtually everywhere. Interestingly, certain bacterial species have a resting state known as the endospore stage. Bacteria in this form can be among the most indestructible of all living things. Apparently, only long periods of high-pressure steam will cause some endospores to die.

 

For humans, certain bacteria can pose very real health dangers. For example, staphylococci can cause strep throat, and bacteria known as pleuropneumonia-like organisms (PPLO) can lead to contagious pneumonia. Other pathogenic (disease causing) bacteria are responsible for salmonella, Legionnaire’s Disease, and botulism. Unfortunately, under ideal circumstances, most bacteria can divide and multiply about every twenty minutes. As a matter of fact, theoretically, one bacterium could produce one-half-million descendants within six hours. Therefore, diseases caused by bacteria often have the potential to spread rapidly.

 

To counter the proliferation of dangerous bacteria in your home, it’s extremely important to not create hospitable living conditions for them. Therefore, be sure to store all your food properly, have good personal hygiene habits, keep all indoor pets well groomed, clean your house thoroughly and regularly, and avoid having standing water or persistently high relative-humidity levels in your home. Also, make sure any humidifiers you’re using are frequently cleaned, perhaps daily in some cases. It’s also a good idea to disinfect your humidifiers from time to time with hydrogen peroxide (use the 3% solution sold in most pharmacies), or with some other tolerable disinfectant/cleaner.

 

You may also want to use special air-cleaning equipment. Certain air purifiers and filters, such as HEPA filters or electrostatic filters will help remove airborne bacteria. While it’s true that ozone generators can also counter bacterial levels by broadcasting streams of reactive ozone (O3), ozone can also react with your mucous membranes, wall finishes, household furnishings, and more. So this approach is not recommended. Finally, ultraviolet (UV) light purifiers can be effective bacteria killers. Incidentally, there is a small amount of ozone produced when using UV purifiers.

 

 

Viruses

 

Viruses are extremely minute parasites that, by definition, border somewhere between life and nonlife. Viruses are found in several forms, the most distinctive being the virion, which basically consists of nucleic acid (reproduction information within a chemical structure) protected with a protein sheath (coating). Virions are the infectious form of viruses that can exist outside host cells. Because of this, the term virus often simply implies the virion form.

 

In reality, viruses differ greatly from one another in both size and shape. However, most are only 3,000 angstroms long (An angstrom is one ten-billionth of a meter.). Viruses can’t function or reproduce completely on their own and must invade a host species’ cells. Once in a compatible cell, the virus injects its nucleic acid into that of the host cell. This eventually causes the host cell to reproduce the virus. However, although there are hundreds of virus strains, only a limited number are actually a threat to humans. Viral infections that can occur in people include polio, mumps, German measles, chicken pox, influenza, hepatitis, AIDS, and herpes. Even some cancers are thought to be caused by certain viruses.

 

Relatively high levels of airborne infectious viruses are present most commonly in the air of your home when a family member or pet currently has a viral disease. Therefore, vaccinations of those family members still unaffected is the best preventive—if a vaccination for that particular illness is available. By the way, ozone generators may be able to kill certain viruses through the action of the reactive ozone (O3) gas. However, these aren’t recommended because their very reactivity can negatively affect human health as well as a home’s belongs. Another approach is to use an ultraviolet (UV) light purifier to kill the viruses, but these devices also have their drawbacks.

Dust-Mite Fragments and Feces

Although it’s admittedly disgusting to think about, dust-mite body parts and feces often make up a fairly large portion of house dust. In fact, one estimate has it that a quarter million dust-mite fecal pellets can be found in is a single gram (about a 1/2 teaspoon) of house dust. Interestingly, it’s the lightweight dead body parts and fecal pellets, and not living mites themselves, that tend to become airborne. For susceptible individuals, this dust-mite debris can trigger asthmatic or allergic symptoms that range from mild sniffles and itchy eyes, to life-threatening respiratory distress. One condition dust mites can cause, but is far less commonly known, is atopic dermatitis. Also known as eczema, it is a chronic inflammatory skin condition. It apparently often runs in families that have histories of asthma, and certain allergies such hay fever.

 

Unfortunately, dust mites are found in virtually every home, perhaps in as many as 90% of them. These tiny (usually less than 0.04" in length), eight-legged creatures are invisible to the naked eye. (They weren’t even discovered until about three decades ago.)

 

To minimize dust-mite populations, and their debris, you should dust and vacuum your home frequently and thoroughly. To make this easier, those with serious dust-mite allergies should consider having only hard-surface floors, as well as easily cleanable, or washable, furnishings and decorating items. Because dust mites thrive at higher relative humidities, they can often be minimized by keeping your house drier.

 

While HEPA filters are commonly promoted as the best air filters for allergic persons, the truth is that many types of less-efficient particulate air filters are able to trap dust-mite debris. On the other hand, negative-ion generators may not one of the better methods.

Mold

Mold tends to be both ugly and destructive in homes. This section discusses what mold is, possible outcomes, if present in your home, and methods of dealing with it.

 

 

The Nature and Potential Consequences of Mold

 

Mold is a popular term for those fungi having hyphae (threadlike filaments). Living mold, dead mold, and mold spores are common airborne allergens (substances that trigger allergic symptoms). Molds generally thrive best where moisture levels are relatively high. Under the right conditions, mold can grow on almost anything. Therefore, tile, grout, wood, paint, plaster, and fabric are all susceptible to mold.

 

Unfortunately, mold growth is unsightly and it can cause permanent staining and damage to walls and furnishings. Sometimes, unpleasant odors also accompany mold growth. These odors are the gases given off by the mold’s metabolic processes, which sometimes include potentially harmful volatile organic compounds (VOCs). Sadly, once your belongings become moldy, it’s often difficult to completely eliminate the stains or the musty odors.

 

Testing and Eliminating Mold in Homes

 

If desired, you can hire an environmental-testing company to test your indoor air for its mold content. You can also buy home test kits for mold.

 

However, in certain situations, it’s probably questionable what real benefits you will derive from testing your home for mold. After all, in most cases, if you suspect a mold problem, its because you can already see it or smell it.

 

Generally, the best way to guard against mold is to create an indoor habitat that’s unappealing for colonization. This is done by properly storing your food, and cleaning your home and clothing frequently. You should also eliminate any moisture problems in your house. That means fixing leaking water pipes, drains, gutters, roofs, and foundations. Another important step is reducing the indoor relative-humidity levels if they’re too high. In the winter time, when the indoor relative humidity is below 40%, mold growth tends to drop off dramatically.

 

By the way, very common airborne mold sources in homes are contaminated air conditioners, humidifiers, and dehumidifiers. (Note: For highly mold-allergic people, it’s best to keep the number of such water-filled appliances to an absolute minimum.) To help prevent mold growth from starting in your air conditioner, try running just the fan for thirty minutes immediately after you turn the cooling function off. This will help dry out your air conditioner’s inner components. For humidifiers and dehumidifiers, your best defense is to keep them as clean as possible. For all these devices, remember to clean or replace any filters regularly.

 

If, despite your best efforts, a portable air conditioner, humidifier, or dehumidifier becomes contaminated with mold, you can sometimes get rid of it by doing the following procedure. First, unplug the machine, or shut off the electricity running to it, and place protective plastic sheeting under it, on the floor. Then, carefully—but thoroughly—spray the waterproof parts (never spray anything on or near the wiring, electronics, or controls) with hydrogen peroxide in a spray bottle. (Use the 3% dilution commonly sold in pharmacies.) After that, clean by hand what you’re able to dismantle or easily reach using a sponge soaked in hydrogen peroxide. Afterwards, let the unit dry thoroughly before using. When doing this, remember to wear protective eye wear, and a chemical respirator mask to protect yourself from inhaling mold spores, as well as waterproof gloves to protect your hands. Of course, if you are allergic to mold, this generally isn’t a project to do yourself.

 

By the way, if the walls of your home, or some of your possessions become moldy, wash off the mold promptly using an appropriate mold-killing solution—that is, one that’s tolerable to you and won’t damage what you’re trying to clean. Another approach, that can work if moisture problems have caused the mold growth, is to fix the leaks and high humidity, etc. Then, once the mold has become dormant, clean it up while wearing a chemical respirator mask as protection against breathing the mold particles.

 

In the winter, closets can have a higher relative humidity than other rooms in a house, so they can also be places where mold can grow.

 

Several air-filtering strategies including HEPA filters can also trap airborne mold. Ozone generators reduce mold levels by the use of the unstable, highly reactive ozone (O3) gas they release. While an ozone machine can prove effective at killing mold, it is so unstable that it can easily react with more than fungi, including wall finishes, furnishings, and human mucosal tissues. So, ozone generators are not recommended, unless a professional does the job and no one is indoors while the unit is operating. Even then, unexpected new odorous compounds could be created as the result of the ozone’s reactivity. These may be as problematic as the mold, in some cases. The truth is, none of these approaches are the best way to control mold. Eliminating excess moisture and high relative humidity is always the best and most permanent solution.

Pollen

Pollen grains are actually gametophytes of male plants, which is equivalent to sperm in male animals. The amount of pollen produced by different plant species varies enormously. However, most plants produce huge quantities of it. For example, the number of pollen grains from just one pine cone often runs in the millions.

 

Each plant species has pollen grains that are uniquely shaped, but virtually all types of pollen grains are very small. In fact, most pollen grains are between 24 and 50 microns. (One micron is one-millionth of a meter. A fine human hair is about 40 microns in diameter.) Interestingly, pollen grains contain proteins and sugars, some of which act as insect and animal attractants. This is because intermediary creatures are often necessary to help transfer the pollen to the female flowers.

 

Of course, pollen grains are both natural, and an essential part of life. Unfortunately, high airborne levels of pollen can be irritating to many people’s eyes and sinuses. In some individuals, certain types of pollen grains can provoke allergic symptoms or asthmatic attacks. If pollen is a health concern for your family, you may want to take measures to minimize its levels inside your house. Obviously, you won’t want to bring any flowering plants indoors. Also, it’s a good idea not to plant trees or shrubs too near your home. After all, the potentially huge quantities of pollen produced by your landscaping could easily enter through doors, windows, and the home’s ventilation system.

 

However, for very allergic individuals, these approaches may still not be enough. Because tiny, extremely lightweight, pollen grains are hardy and somewhat indestructible, they can be carried by wind currents for great distances. If conditions are right, tree and plant pollens from many miles away could end up in the air just outside—and, therefore, eventually inside—your house.

 

Fortunately, there are a number of air-cleaning strategies that help reduce indoor pollen levels. Although pollen grains are small, most are still large enough to be trapped by many types (if not most) of particulate air-filters.

 

 

Minerals and Metals

 

Harmful minerals and metals are particulate pollutants that can be found in indoor air. Two in this category of which you should be aware are asbestos and lead.

Asbestos

Just saying the word asbestos can trigger a certain amount of fear among many people. Although asbestos definitely can cause severe respiratory illnesses, in certain situations in your home it’ll pose very little risk to you or your family—if it is not deteriorating, and you don’t disturb it.

 

The Nature, Uses, and Potential Health Consequences of Asbestos

 

Asbestos is actually a generic term that’s applied to several minerals that occur in a fiber-like form. However, chrysotile (the fibrous form of serpentine) is usually the particular type meant when the word asbestos is used. Unfortunately, if small asbestos fibers become inhaled, minute fragments can become trapped in your lung tissue. This can lead to very serious consequences. In fact, since the mid-1960s, exposure to asbestos in the workplace (asbestos mines, asbestos-insulation factories, etc.) has been known to cause asbestosis (a severe, debilitating lung disease), as well as lung cancer.

 

Concern over asbestos exposure, since these findings first became known, has steadily increased. As a result, in 1971 asbestos became the first regulated material in the workplace by the U.S. Occupational Safety and Health Administration (OSHA). Then, in 1986, OSHA decided to severely limit the acceptable exposure levels for workers. However, it was not until 1989 that the EPA (Environmental Protection Agency) regulated asbestos beyond the workplace. That year, the EPA ordered that asbestos use, manufacture, and export be reduced 94% by 1996. Asbestos was also completely banned in some building materials as well as brake linings.

 

Yet, a tremendous amount of asbestos is already present in our environment. Because asbestos fibers are fire-, heat-, and corrosion-resistant, and they can be spun, woven, compressed, or added to other substances, asbestos has been widely used in industry as well as in commercial and consumer products. For example, over the years, it has been an integral ingredient in brake linings, hard flooring materials (such as certain types of vinyl tiles), some cement and cement products (including cement/asbestos siding and roofing tiles), and even in some drywall compounds. It’s also been used as insulation surrounding ductwork and furnaces, as well as with particular types of electrical circuitry. As a result, many U.S. homes contain at least some quantity of asbestos. The exceptions, of course, would be those houses that have been more recently built

 

Testing and Eliminating Asbestos in Homes

 

It should be pointed out that asbestos in your house may not necessarily be a problem. For instance, asbestos imbedded in older cement siding materials is unlikely to create asbestos dust that can be inhaled. However, one of the worst situations is having deteriorating asbestos insulation surrounding your ducts or furnace. In such a case, the asbestos should be removed completely, carefully, and as soon as possible. This isn’t a job for homeowners or amateurs, but one that must be performed only by licensed asbestos-removal contractors.

During the removal process, there must be a complete sealing off of the contaminated areas, workers must wear hazardous-material protective gear, and special hazardous-material disposal methods are used.

 

If you suspect any sources of airborne asbestos in your home, call your local board of health, which can advise you on what steps to follow, including testing. If an asbestos problem is confirmed, health officials may be able to suggest approved asbestos-removal companies. In order to get a reliable asbestos-removal firm, it would be wise to obtain several homeowner references from jobs they’ve previously performed, a written estimate of the total cost, and the projected time in which the removal procedure will take place. You should be aware that asbestos removal can often be expensive.

 

Although other filtering methods might be able to trap asbestos fibers, depending on their size, very efficient HEPA filters would be the logical choice to use with such a potentially dangerous material. However, in reality, the best protection is to eliminate any deteriorating asbestos. For more information on asbestos, contact the EPA National Service Center for Environmental Publications. The particular agency offers booklets addressing issues regarding asbestos in homes. By the way, the EPA also sponsors an EPA Indoor Air Quality InfoLine that you may want to call.

Lead

Lead particles pose a real health threat in far too many U.S. homes. The following sections explain why this is the case.

 

 

The Nature, Uses, and Potential Health Consequences of Lead

 

Lead (Pb) is a very heavy, silvery-gray metal that turns a dull blue-gray when exposed to the air. It’s also soft, malleable, and has a low melting point. Interestingly, once lead has oxidized (tarnished), it becomes corrosion-resistant. Lead can be alloyed with many metals (Pewter was originally a combination of lead and tin.).

 

Lead has been widely utilized over the years. It’s been used as a whitening pigment (known as white lead) in paints—and even in face powders at one time. It’s also been widely used as an inexpensive and useful solder. In addition, it’s been used to make water pipes, fishing sinkers, molded toys, printing type, and gun shot. Today, lead continues to be an essential component of lead-acid automobile batteries and it is sometimes used to create waterproof barriers in certain roofing applications. Furthermore, lead is used as came (supporting strips) in some stained-glass work, as an ingredient in certain glossy ceramic glazes, and in the making of lead crystal, among many other uses. However, deteriorating lead paint usually poses the most health concern in homes.

 

Despite its useful qualities, lead has a serious drawback: It can be poisonous. For a number of years, it was suspected that lead might be responsible for certain workplace-related negative health effects seen all too frequently in lead mines and lead foundries, etc. Yet these workers were exposed to amounts then considered safe. However, research finally proved the feared correlation between illness and “low-level” lead exposures. Because of this, since the mid-1980s, the U.S. Centers for Disease Control (CDC) has been steadily lowering what officials there consider the acceptable “environmental lead level.”

 

Actually, what’s currently known is that lead, and many lead-containing compounds, can be toxic when swallowed or inhaled. While lead is absorbed by the human body at a very slow rate, it can gradually accumulate in fairly large amounts because it can’t be easily eliminated. Unfortunately, high lead levels can injure the central nervous system and damage the blood-brain barrier cells that provide a natural shielding of your brain tissue against potentially harmful chemicals.

 

Signs of lead poisoning include loss of appetite, weakness, anemia, vomiting, and convulsions. In some cases, permanent brain damage can result—even death. In children, impaired learning or kidney problems can sometimes be caused by lead poisoning. In adults, hypertension (high blood pressure) can also be a symptom of high lead levels in the body.
Because a variety of studies have documented that children have been made ill by eating and breathing deteriorating lead paint, the federal government banned lead as a paint ingredient in 1977. More recently, lead has been banned in solder. In addition, lead additives in gasoline, such as tetraethyl lead and tetramethyl lead, have been phased out. In the past, some of these additives probably routinely entered the living spaces of homes with attached garages.

 

 

Testing and Eliminating Lead in Homes

 

These days, it’s now agreed by virtually all experts that everyone should completely avoid lead dust and lead fumes, if at all possible. Therefore, if you’re concerned whether your wall paint contains lead, you might want to perform a lead test on it. Test kits can be purchased from various online sources. If you find evidence of lead in your wall paint, contact your local board of health for information on what steps to take. Lead tests can also be used on pottery, dishes, etc. that are suspected of having problematic lead glazes.

 

For more on lead, you can call the National Lead Information Center which is a Hotline maintained by the EPA (Environmental Protection Agency). After contacting the Hotline, you’ll be sent printed materials about lead poisoning, and measures you can perform to prevent it, as well as a list of helpful state and local agencies (such as local and state boards of health, etc.), and additional information.

 

Although air-filters for removing airborne lead might be suggested, lead dust is generally too heavy to become airborne. However, HEPA-filtered vacuums are one of the more effective methods of removing it. Yet, with such a toxic metal, the best protection is to sufficiently seal the source of the lead, or have it professionally removed.

 

 

Mixed Contaminants

 

House dust and smoke are actually made up of several types of pollutants. The following sections give you information on these two complicated substances so you’ll be better able to deal with them more effectively

Dust

Every home contains a certain amount of house dust. But exactly what is it and how do you best deal with it?


The Nature and Potential Health Consequences of Dust

 

House dust is a generic term that can be defined as fine, dry particles of earth and other debris. In homes, it is usually made up of many components, such as soil, lead, perhaps asbestos, natural or synthetic fibers, dander (skin flakes), hair, fur, pollen grains, mold spores, dust-mite body parts, dust-mite feces, both live and dead bacteria, as well as many other things. Actually, the exact make-up of the dust found in each home is unique to that home.

Not surprisingly, many people find that breathing dust can be irritating to the nose and sinuses. In addition, certain individuals have asthmatic or allergic responses when they inhale dust—sometimes suffering severely from it. In reality, it’s often only one component, or perhaps only a few, in the dust, that actually triggers these autoimmune symptoms. Most commonly, the problem is related to certain pollens, mold spores, and dust-mite debris.

Of course, the best defense against indoor dust is to thoroughly and regularly clean the interior of your home. If you frequently dust using a damp, all-cotton, flannel cloth, for example, it can help eliminate a great deal of the particulate matter that lands on your tables, lamps, accent pieces, and dressers, etc. If you vacuum your floors, walls, and upholstered furniture regularly with a central vacuum system (with an outdoor exhaust) or a specially filtered portable unit, it can also help cut down on the quantity of accumulated house dust.

To remove airborne dust from your home, you can use one of many air-cleaning and air-filtering approaches designed to remove particulates.

Duct Cleaning

Furnace and air conditioning ducts commonly acquire a layer of house dust in them over time. Therefore, it’s a good idea to have your home’s entire ductwork system cleaned from time to time. Fortunately, professional companies now specialize in this field, many of which use a powerful vacuuming procedure.

You may find that some duct-cleaning contractors want to use a disinfectant (sometimes fragranced) in your ducts. The disinfectant treatment is meant to inhibit the growth of biological contaminants such as microbes, dust mites, fungi, and bacteria. And if it's scented, it’s meant to act as a deodorizing “air freshener.” However, it is generally wise to avoid having these chemicals used in your ducts, because they can leave odors in them for some time. Naturally, this is an important consideration for chemically sensitive persons.

To locate a professional duct-cleaning service, check in your local classified telephone directory. If you don’t see any listed, you might ask for suggestions at your local board of health, or from an area heating/cooling contractor. If you do find a company, ask specifically about their procedure for cleaning ducts, what cleaning products or chemicals, if any, they normally use, any bonding or certification, as well as time and cost estimates.

Smoke
Smoke is a surprisingly complex substance whose effects can linger long after the combustion that created it has been extinguished. The sections below explain what’s in smoke, and how it can affect you if it is inhaled.

The Nature and Potential Health Consequences of Smoke

Smoke is a by-product of combustion. It is actually considered a mixed aerosol of gases, suspended liquid vapor droplets, and very tiny solid particulates. Unfortunately, if you breathe in smoke, these minute solids can be particularly damaging to your respiratory system, especially your lungs. Interestingly, if the combustion gas sulfur dioxide is also present, the particulates can become even more deeply imbedded in your lung tissue than they otherwise would. In any case, bronchitis, asthma, emphysema, and even lung cancer can result from breathing in smoke. And too much smoke inhaled at one time can easily result in death. The particular effects you’ll experience from inhaling smoke depend on the origin of the smoke (wood, tobacco, or synthetic vinyl, for example), its concentration in the air, the length of exposure, and your own personal susceptibilities.

In homes, controlled sources of smoke can include burning kerosene lamps, candles, incense, fireplaces, and wood stoves—and, of course, tobacco. While the health risks associated with smoking are now well publicized, fewer people understand the very real dire effects of breathing secondhand smoke. This is understandable considering this “used” smoke is up to one-hundred times more poisonous than the smoke originally inhaled by the smoker. Also, researchers have found that rooms filled with tobacco smoke can have air pollution levels six times that of busy highways. Apparently, in work situations, employees exposed regularly to secondhand smoke are one-third more likely to get lung cancer. The EPA (Environmental Protection Agency) has, in fact, classified it as a Group-A carcinogen. Finally, secondhand-smoke exposure tends to increase the chances of acquiring childhood asthma.

Of course, unplanned combustion in the form of accidental fires can be devastating sources of smoke in houses. This is because the amount of smoke produced from even a very small, localized fire can be both massive and pervasive. It’s no wonder then that smoke inhalation causes more injuries and deaths in home fires than burns.

Removing Smoke From Your Home

Besides the direct health effects, smoke can easily permeate and saturate your clothing, furnishings, walls, and flooring. Unfortunately, smoky odors can often be difficult to get rid of completely. Sometimes, even repeated cleaning, and extended airing, may not remove all the smell. However, in certain cases, some individuals have found that ozone generators have been somewhat helpful. Apparently, the very reactive ozone (O3) is able to break down the compounds that make up the smoky odors. However, if this approach is tried, it should only be done by a professional, and with no one inside the home. You should also be aware that the ozone will possibly react with other materials it comes into contact with indoors. As a result, new, unplanned compounds may be inadvertently created, some of which could be bothersome in their own right.

Many people ask, "What’s the best air filtering strategy to eliminate smoke in the air?" There’s not an easy answer, you see, because smoke is a mixture containing both solid particulates and vapors, and it is also accompanied by combustion gases. Therefore, it requires an air-cleaning system capable of removing several types of contaminants. Actually, because the particles in smoke are often so extremely tiny, HEPA filters are probably the best type to use. In addition, activated charcoal would also be necessary to adsorb the gases. Note that an air-cleaning system can easily become overwhelmed, and rendered more or less useless, if the concentration of smoke in the air is very high. Ideally, in a healthy home, there should be no sources of smoke whatsoever.

 

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Indoor Air Quality - What It's All About:  Created on May 28th, 2007.  Last Modified on December 19th, 2013

 

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