It is estimated that we now spend more than 90 percent of our time indoors. Our health and well-being are notably affected by the large amount of time we spend indoors. In part because of dust, mold, lead, and asbestos in the home, more than 38 percent of Americans suffer from allergies, resulting in a variety of symptoms ranging from runny noses and fatigue to learning problems and epilepsy. Moreover, asthma, which is linked to animal dander, paint fumes, dust mites, cockroaches, molds, pollens, and indoor secondhand smoke, is on the rise. From 1980 to 1994, the number of asthma cases grew 75 percent to over 17 million. We are just beginning to understand the connections between many more ailments — some life threatening — and your home.
Indoor air quality represents a considerable challenge for several reasons. First, the current method of determining IAQ is not related to any health or productivity measure. Rather, it is simply a function of the percentage of people who are dissatisfied with a space: if 20 percent are dissatisfied, the building has poor indoor air quality Not only does this measure ignore health care costs, productivity, and crippling law suits, but it is technically inaccurate.
Second, pollution laws in general focus more on the sources of the greatest amounts of pollution, rather than on the sources of the greatest amount of exposure to pollutants. Smoke stacks emit large amounts of pollution, but most of us do not live next door to one. Our homes, on the other hand, emit relatively small amounts of pollution, and yet they are often the places where we face the greatest exposure to health-threatening pollutants.
Third, in recent years we have become more concerned with energy efficiency and sealed up our homes more tightly without consideration for proper ventilation. In effect, as cabinets, carpets, furniture, stoves, and many other common household items contribute to indoor air, they build up to unhealthy concentrations because they can not escape from the house as they might in a leakier home.
By remodeling green, you can prevent serious health issues related to indoor air. It is important to understand the sources of your exposure to toxic pollutants in your home, including showers (chloroform), stoves (carbon dioxide, respirable particles), and carpets (lead, pesticides). Additionally, there exist many often- unrecognized indoor pollutants that you should be aware of as you remodel. We have organized all these pollutants into six overarching categories to clarify the indoor air quality issues in your home and allow you to make simple, healthy remodeling choices:
1. Particulates (lead, asbestos, fiberglass, dust)
2. Combustion gases (carbon monoxide, nitrogen oxide, hydrocarbons)
3. Volatile Organic Compounds (VOCs — formaldehyde, pesticides, vinyl chloride, soil gases)
4. Radioactive contaminants (radon gas)
5. Environmental tobacco smoke
6. Moisture and mold
Particles, sometimes called particulates, are small specks of solid matter. Common household dust can include microscopic particles from fabrics, soil, plants, insulation, human and animal dander, food, dirt, paint, plastic, soot and cigarette smoke. The particles themselves can carry harmful chemicals, such as lead. In addition, particles can carry dust mites, or tiny insects that live on the dust itself. Many of these are biological allergens that can cause reactions ranging from sneezing arid running eyes to heart palpitations, internal pains, and loss of muscle control.
Particulates are especially dangerous to small children, who play on floors, crawl on carpets, and regularly place their hands in their mouths. Infants are particularly susceptible: their rapidly developing organs are more prone to damage, they have a small fraction of the body weight of an adult, and they may ingest times more dust — 100 milligrams a day on average. Carpets act as a reservoir for particulates, especially plush and shag carpets. Vacuuming hard- surface floors will remove almost 100 percent of dust, while vacuuming a carpet typically removes only 30 to 60 percent of the dust. However, wiping one’s feet on a commercial grade doormat appears to reduce the amount of lead in a typical carpet by a factor of 6.’ A central vacuum that vents outdoors and a vacuum with a high-efficiency filter are the best options to keep particles to a minimum.
Lead has long been recognized as an especially dangerous particulate. It impairs mental and physical development in fetuses and young children and decreases coordination and mental abilities. Additionally, lead damages the kidneys and red blood cells, and may increase high blood pressure.” The margin of safety between measured blood levels and the levels causing clinical symptoms is remarkably small; only a slight increase in lead concentration in children’s blood levels is necessary to cause anemia and the onset of mental losses. Low exposures can be even more dangerous than higher exposures because there are no visible symptoms, but the subtle learning and behavior problems can go on untreated for years.
Children, especially between the ages of six months and six years, are at high risk because they are more likely to ingest lead particles, and because harmful effects begin at lower blood levels. Lead enters the body when an individual breathes or swallows lead particles or dust once it has settled. There are many ways that humans can be exposed to lead: through air, food, contaminated soil, deteriorating paint, and dust. Additionally, pipes, solder in pipe joints, and home plumbing can release lead into your drinking water; in some instances, this may account for up to 40 percent of your family’s lead exposure.”
If your house was built before 1950, you almost certainly have some paint with high lead content — the most significant source of lead exposure in the US today.” According to a 1990 study by the US Department of Housing and Urban Development (HUD), 75 percent of all private housing built before 1980 has some lead paint. If the house has been repainted, the old paint has been sealed in. However, if the new paint deteriorates or is improperly stripped, it can create a new hazard.
It is especially important for children and pregnant women to avoid drinking, eating, or breathing lead because growing children and developing fetuses are the most vulnerable to lead poisoning which can cause irreversible brain damage and behavior and learning problems, and delay mental and physical growth. Kids tend to get lead on their hands and then put their fingers and lead-ridden objects in their mouths, so they are likely to have higher exposure. The US Centers for Disease Control (CDC) estimates 890,000 children in the US between the ages of 1 and 5 have elevated lead levels in their blood.
To avoid lead in your home, have old paint lab-tested for high lead content before major renovations. Leave paint undisturbed if it is not accessible to children and if it is in good condition. Replace doors, windows, or trim covered with lead paint, or strip and repaint them away from the house. If you want the paint removed on-site, have it done by a trained contractor. The work will be dusty, so you should move the family out the house during the work, and clean up thoroughly before moving back in. Also, have your water tested for lead content. If the results show high lead levels, replace old plumbing or install a point-of-use water purification device, such as a reverse osmosis system or distiller.
Asbestos is a naturally occurring particulate with long, flexible fibers that can lodge in your lungs. There are no immediate symptoms, but prolonged exposure can cause asbestosis (severe impairment of lung function), or cancer of the lung or lung cavity. Asbestos can also cause cancer in the digestive tract if fibers are inadvertently swallowed. Smokers are at a higher risk of developing asbestos- induced lung cancer.
In 1974, after the elevated risk to asbestos workers was documented, asbestos was banned for interior use in the US. It still exists in many homes today and is difficult to remove, given that if any of the products mentioned above are damaged, improperly removed, or get disrupted in any number of ways (like sanding), it is likely that the asbestos will become airborne. However, most asbestos is embedded in other materials, such as ceiling tiles or pipes, and is not as dangerous in that form.
Appliances that burn fuel, such as furnaces and fireplaces, commonly leak at least small amounts of the gases created during combustion. They will emit larger amounts when the appliances are not working properly, or when another appliance or system, such as a bathroom fan or range hood, draws air from the house and causes normal chimney flow to be reversed, known as backdrafting. This negative pressure causes gases to be drawn back down the chimney or exhaust duct, and into the house. For example, leaky return-air ductwork, fireplaces, down-draft kitchen exhaust fans, undersized cutouts through floor plates for return-air drops, normal exhaust fans (kitchen range hoods and bath fans), dryers, central vacuum systems, large combustion air ducts located on the sheltered side of a home, and large penetrations into attics, such as whole- house fans, can all cause backdrafting.
Although you can’t see, taste, or smell carbon monoxide (CU), this combustion gas is responsible for a larger number of severe chemical poisonings than any other single agent.” When breathed, carbon monoxide preferentially binds to blood hemoglobin, displacing oxygen at the binding site and thereby depriving the body of oxygen. Early symptoms of carbon monoxide poisoning include persistent headaches, nausea, fatigue, blurred vision, rapid heartbeat, loss of muscle control, and flu-like symptoms that clear up upon leaving the house. More severe exposures cause vomiting, collapse, coma, and death, depending on the degree of oxygen deprivation. Suicidal or accidental death from running a car in an enclosed garage or from using an unvented, poorly tuned combustion appliance indoors results from depression of the central nervous system to the point where breathing is stopped. The Consumer Products Safety Commission reports that more than 200 people in the United States die from CO poisoning every year.
In addition to carbon monoxide, fuel-fired appliances also emit other combustion by-product pollutants, including formaldehyde, nitrogen dioxide, sulfur dioxide, carbon dioxide, hydrogen cyanide, nitric oxide, benzo(a)pyrene, and vapors from various organic chemicals. At low levels produced from average use from combustion appliances, possible symptoms from exposure to these by products include eye, nose, and throat irritation; headaches; dizziness; fatigue; decreased hearing; slight impairment of vision or brain functioning; personality changes; seizures; psychosis; heart palpitations; loss of appetite; nausea and vomiting; bronchitis; asthma attacks; and breathing problems.
The most effective way to avoid combustion by-products is to use all-electric appliances — range, heaters, water heaters, and clothes dryers. Self-cleaning electric ovens are one exception because they produce carcinogenic polynuclear aromatics that are on the EPA list of priority pollutants. In general, however, indoor air pollution studies show that all-electric homes have significantly lower concentrations of combustion by-products than do homes with gas appliances.
You can still use gas appliances and protect yourself somewhat by ensuring that fuel-burning appliances like furnaces, hot water heaters, stovetops, and fireplaces are properly ventilated. If you are replacing your furnace or water heater, consider using a sealed combustion unit that isolates the appliance from the indoor space. During cooking, for example, a hood fan can remove up to 70 percent of pollutants produced.” If possible, put your gas appliances in a space outside of the living area, venting the fumes to the outside and placing a tight seal between the appliance and the living space to prevent gases from spreading throughout the home. Use a new-model gas stove with low-heat-input gas pilot light and non-gas ignition systems, which produce significantly lower pollutants than do older stoves with pilot lights.
For wood stoves and fireplaces, make sure they are installed and fitted properly. Have your chimney inspected for creosote buildup when the weather starts getting cold, or periodically throughout the year if you frequently use your fireplace. Fix cracks or leaks in the stovepipe and keep a regular maintenance schedule to keep the chimney and stovepipe clean and unblocked. Have your fireplace retrofitted with an insert that draws air from the outside and has airtight doors that can be closed when you leave the room.
Finally, beware of negative air pressure and downdrafts indoors that can pull pollutants into your living space instead of up the flue. Eliminate the problem by installing only sealed combustion appliances. If this proves too expensive, reduce the backdrafting by selecting only fan-driven, draft-induced water heaters and eliminating any wood or gas fireplace that isn’t sealed combustion. Other alternatives include carefully sealing all ductwork with mastic, installing a return- air duct in all the bedrooms, and selecting a standard kitchen range hood rather than an excessively powerful downdraft exhaust cooktop, which can suck too much air out of the house too fast, causing negative air pressure. Keep in mind that “leakier” homes are not a solution; this merely makes the home uncomfortable and more expensive to heat and cool. Moreover, if leaks are located in the wrong places, they can add to unbalanced pressure and introduce combustion gas issues in the home.
Volatile Organic Compounds (VOCs)
Many of the hazardous chemicals in modern houses are members of a large family called volatile organic compounds, or VOCs. The distinctive smell of a newly remodeled house is primarily composed of offgasing toxic volatile organic compounds. They are commonly found in plywood, particle board, wood paneling, carpets and carpet padding, insulation, paints, finishes, adhesives, heating fuels, solvents, waxes, polishes, and many other household products.
VOCs found in the home include formaldehyde, benzene, xylenes, toluene, and ethanol. There are several main concerns with VOCs. First, VOCs contribute to pollution outside by reacting with sunlight to form ground-level ozone, a major component of smog. Second, VOCs’ effect on indoor pollution is even worse — the Environmental Protection Agency’s total exposure assessment methodology (TEAM) studies have found indoor levels of common organic compounds to be two to five times higher than those found outside. Third, producing many of the binders and solvents in wood finishes creates significant amounts of hazardous wastes. If leftovers are discarded into the trash, they contribute to air pollution. When poured down the drain, they contribute to water pollution and clog your sinks and water pipes in the process. and finally, petroleum-based finishes (like most wood finishes) contribute to the depletion of this non-renewable resource and increase our nation’s dependence on imported oil.
While some building products now report the parts per million of VOCs on labels, this information can be misleading. Fewer parts per million is certainly better, but chemicals like dioxin are not safe in any detectable amount.
Another one of the more lethal VOCs in the home is formaldehyde. It comes primarily from the adhesives in pressed wood products, such as particleboard, hardwood paneling, and medium density fiberboard. It is also found in urea formaldehyde foam insulation (UFFI), combustion sources, environmental tobacco smoke, durable press drapes, some other textiles, and glues. Building materials can off-gas formaldehyde for five or more years following manufacture. The amount of formaldehyde released from building materials increases as temperature increases — for example, during the winter when indoor heaters are on and there is little ventilation from windows.
Several studies have shown that a significant portion of the public is exposed to formaldehyde at levels high enough to produce symptoms such as eye, throat, and nose irritation; wheezing and coughing; fatigue; skin rash; and severe allergic reactions. Symptoms have occurred at levels as low as 0.05 parts per million — the level that has been proposed as the California indoor air quality standard.’ Over time, some people develop heightened sensitivities to formaldehyde — in other words, once a person is exposed, even minute exposures to formaldehyde can induce health problems.
The long-term effects of prolonged exposure to low levels of formaldehyde — levels typically found in mobile homes or energy-conserving buildings — are controversial. Still, the EPA has concluded that formaldehyde is a probable human carcinogen on the basis of experimental studies and human epidemiological studies and laboratory tests. In the human epidemiological studies, they found increased incidence of brain tumors, leukemia, and cirrhosis of the liver among workers exposed to formaldehyde. Laboratory studies indicate that formaldehyde causes nasal cancer in rats and that it appears to cause mutations in bacteria, yeasts, fruit flies, and mammalian and human cells.”
To reduce your exposure in the home, keep in mind that medium-density fiberboard emits about three times more formaldehyde than particleboard. and plywood, although made with a formaldehyde resin, is preferable to particle- board. Also, exterior grade plywood emits less than interior grade. “Swedish” hardwood floor finish is notorious for high formaldehyde emissions: it is banned in Sweden and many other areas.” The best option is to choose pre-finished solid wood flooring or use water-based finishes.
In addition, use air conditioning and dehumidifiers to maintain a moderate temperature and reduce humidity levels. Insist on carpet or carpet pad with little or no formaldehyde content. Also, apply surface barriers (such as low-VOC latex paints and primers) to particleboard or plywood to reduce offgassing. These vapor barriers can reduce formaldehyde emissions by up to 95 percent, but tend to break down after several years and require reapplication. Foil tape can seal the edges and keep fumes from escaping.
Finally, open the windows! This is particularly important after bringing new sources of formaldehyde into the home. A notable consumer advocate also recommends spider plants to absorb formaldehyde: “You’ll need about 70 Chlorophytum elatum (spider plants) in one-gallon containers to purify the air in an average 1,800-square-foot energy-efficient home (a veritable jungle!), but don’t be overwhelmed.”
Although some pesticides may technically be considered VOCs, these often odorless and invisible substances have become such a health threat that they warrant a separate discussion. According to the World Health Organization, more than 3 million people get sick, and 220,000 die worldwide from pesticides each year. In the United States alone, pesticides poison 110,000 people each year. More than one-third of calls to animal poison control centers result from pets exposed to pesticides.
Pesticides, or biocides, are poisons designed to kill a variety of plants and animals such as insects (insecticides), weeds (herbicides), and mold or fungus (fungicides). Although pesticides were first developed as offshoots of nerve gas during World War II, many people falsely assume pesticide ingredients are now safe for humans. Would pesticides be on the market if they were unsafe? Yes. The US EPA approves pesticides based on efficacy, not safety, Out of the hundreds of active ingredients registered with the EPA, less than a dozen have been adequately tested for safety.’ In two studies of indoor air quality conducted during the late 1980s, investigators found that indoor air contained at least five (but typically ten or more) times higher concentrations of pesticides than outside air.
Pesticides can be absorbed through the skin, inhaled, or swallowed. Many building products and household furnishings such as paints, wood products, and carpets are treated with biocides. Carpets are especially hazardous; if you have kids, you know that infants and small children are likely to touch and crawl around on them. Also, people and pets may track pesticides into the house from the lawn or even the neighbor’s lawn, allowing the toxins to become trapped in carpets. Pesticides that break down within days outdoors may last for years in carpets, where they are protected from the degradation caused by sunlight and bacteria. For example, the pesticide DDT (dichlorodiphenyltrichloroethane), was outlawed in the US in 1972 because of its toxicity, yet researchers found that 90 of 362 homes they examined in the Midwest between 1992 and 1993 had DDT in the carpets.’
To avoid being exposed to harmful pesticides while remodeling your home, learn to understand the labels on products you buy. You can also reduce pesticide exposure by not treating the soil under the building, and by eliminating standard building products that contain biocides. A well-renovated home will be pest- resistant if it incorporates features like weather tightness; appropriate grading and drainage; ventilation fans and windows that allow cross ventilation to prevent excess moisture buildup from within; dry wood without rot or infestation; exterior wood treated appropriately for prevailing climatic conditions; screens on windows; and ground cover, leaves, chips, wood piles, and other potential insect habitats kept at a distance from the building. If a pest must be eliminated, first see if its current access to nourishment and habitat can be limited. For example, if you have ants, you might clean up crumbs from the floor and counters and caulk the cracks. Second, consider the most benign trapping or killing methods — use the least toxic chemicals you can find, and then only as a last resort!
Vinyl chloride is a widely produced chemical VOC used to make polyvinyl chloride resin, which is the raw ingredient of polyvinyl chloride (PVC) plastic. Vinyl chloride is a colorless gas with a characteristic “plastic” odor. It is widely distributed throughout the industrialized world and can be found in municipal drinking waters, #3 plastics, PVC pipes, vinyl flooring, adhesives, swimming pools, upholstery, and wall coverings in your home.
As dramatized in the movie “Blue Vinyl,” acute exposure to vinyl chloride can induce the feelings of intoxication, The EPA estimates that 15,000 lung cancer deaths each year in the United States dizziness, weakness, and lightheadedness that many kids are drawn to for the same reasons people are enticed by alcohol and other drugs. These symptoms rapidly disappear when exposure is stopped. However, long-term exposure to vinyl chloride can cause cancer, birth defects, genetic changes, indigestion, chronic bronchitis, ulcers, skin diseases, deafness, vision failure, circulatory changes, and liver dysfunction.
Although many plastics are potentially dangerous, some seem to be relatively safe alternatives to vinyl chloride. For example, melamine formaldehyde plastics; such as Formica countertops, are relatively inert. You can also avoid PVC in plastics; instead, use natural materials, like wood and glass.
Know Your Plastics
Not all plastics are equal — some are safer than others. Plastics are typically classified by one of seven recycling codes (found on the bottom of containers), indicating the type of resin used:
FYI: The Environmental Protection Agency estimates that one of every 15 homes in the United States has indoor radon levels at or above the EPA recommended action guideline level of four picocuries per liter (pCi/L) of air.
The EPA estimates that 15,000 lung cancer deaths each year in the United States are due to radon exposure, which makes it the second leading cause of lung cancer in the United States after smoking. Smokers have an even higher risk of developing radon-induced cancer; in fact, many smoking statistics may be caused by the combination of exposure to radon and smoking. The main risk is not from the radon itself, but from radon’s “progency;” or “decay products,” which directly or by attaching to airborne particles may be inhaled into the lungs.
This invisible radioactive gas seeps up into homes through the earth. Its points of entry include floor drains and sumps, joints where the basement wall and floor come together, cracks in the basement walls and floors, holes in the foundation wall for piping or wiring, exposed earth or rock surfaces in the basement, or well water. It is a breakdown product from uranium-238, which occurs naturally in the subsoil. Although it is harmless when it is outside, inside our homes the gas and its decay products can build up to high levels and when inhaled can cause lung cancer. Energy-efficient, tightly sealed homes are especially vulnerable to this accumulation of radon. and because it takes 1,602 years for only half of the radon atoms to disintegrate, radon concentrations tend to become higher as time goes by.
The EPA and the Surgeon General recommend that all homes test their radon levels below the third floor. In the US, the average indoor radon level is 1.3 picocuries per liter (pCi/L), while average outdoor levels are only 0.4 picocuries per liter. The EPA suggests that action be taken to increase ventilation if tests result in a radon level above 4 picocuries per liter. When looking for a radon test kit or mitigation professional, make sure you choose one that is certified by either the National Environmental Health Association (NEHA) or the National Radon Safety Board (NRSB).
If you are adding on to your home, ask your remodeler about methods of radon mitigation that can be incorporated into the construction. For example, you might place an airtight membrane under carpets, or provide some form of under-slab ventilation. Additionally, consider covering any exposed earth with a polyethylene air barrier, and seal all cracks and joints in the foundation wall and floor slab with caulking or foam. You can also install a self-priming drain or gas trap in the floor drains leading to a sump or to drainage tiles, and remove radon from well water using activated charcoal filters or aeration units. Radon-resistant construction features usually keep radon levels in new homes below z picocuries per liter.
Environmental Tobacco Smoke
Environmental tobacco smoke (ETS), also known as secondhand or passive smoke, is the smoke that comes from a burning cigarette, pipe, or cigar, as well as smoke exhaled from the lungs of smokers. ETS is a mixture of over 4,000 chemicals, 200 of which are known poisons, and more than 50 known cancer-causing agents. There is no safe level of exposure to ETS; every year, smoking-related diseases claim approximately 430,700 lives in the U.S.
The best way to deal with ETS is to stop smoking in the house. Otherwise, you can create a separate smoking room, with its own ventilation and air seals to keep the smoke from spreading through the house. An effective ventilation system should supply outside air and incorporate a particulate filter.
Moisture and Mold
Moisture may not be a pollutant, but high or low humidity in a house can make you feel uncomfortable, and can even cause health problems. High moisture levels create a welcoming environment for bacteria, viruses, molds, and dust mites, increases offgasing, and can cause a room to feel stuffy. On the other hand, low moisture levels can cause high dust levels and respiratory infections.
One of the most dangerous effects of high moisture in the home is mold. Molds and mildew (two words for the same thing), are simple plants of the group known as fungi. They grow on the surfaces of objects when the relative humidity, or degree of moisture contained in the air, is high. Mold is commonly assumed to be found only in older homes, but it can be found wherever moisture accumulates, such as basements, kitchens, bathrooms, window sills, carpets, furniture against outside walls, wall cavities, unventilated storage areas, laundry rooms, or wherever leaks and flooding occur. One study showed 16 different kinds of mold in one finished basement. As a general rule of thumb, if you can see it or smell it, you have mold.
And mold spreads! Microbes commonly grow within the ductwork of forced air heating systems, which can result in the spreading of mold and dust throughout the house. Unless kept spotlessly clean, toilets and many modern appliances that use water reservoirs, such as vaporizers and humidifiers, can breed microbes. Many standard construction materials are susceptible to water damage and fungal growth: they can become breeding grounds for mold and bacteria within a few days. Even when molds are contained inside walls or other building cavities such as attics or crawlspaces, the slightest air current can send fungal spores swirling through the air where they are easily inhaled.
Once inhaled, mold produces allergic reactions, hypersensitivity, and infectious diseases. Certain fungi found indoors produce mycotoxins, which can be carcinogenic, teratogenic (induces birth defects), immunosuppressive (reduces immune system performance) or oxygenic (poisons tissues). In addition to health issues, mold discolors surfaces, causes odor problems, deterioration of building materials, and homeowners can incur large bills for structural damage caused by water or water vapor trapped behind walls.
Although the above cleaning methods will temporarily get rid of mold of your home, there are two ways to prevent mold from forming again. First, keep the interior surfaces of exterior walls and other building assemblies from becoming too cold (think of condensation on a cold soda can). Air conditioners tend to cool particular spots on a wall, resulting in mold growth where humid air enters the wall cavity Impermeable wall surfaces, such as vinyl wallpaper, can exacerbate the problem by further trapping natural moisture flow. Therefore, you should prevent the overcooling of rooms, increase the permeability of interior finish materials in humid climates, and relocate ducts and diffusers to elevate the temperature of the surface. Adding insulation to walls, ceilings, ducts, or cold water pipes also raises the temperature of the interior surface and prevents condensation. Air-vapor barriers can be used to keep wall cavities warmer and drier, and two-stud corners reduce heat loss and condensation at corners.
The other way to control mold growth is by limiting interior moisture levels. Install a balanced, whole-house ventilation system that controls moisture by bringing in drier outside air where and when possible. Controlled ventilation, such as venting moist air from bathrooms, clothes dryers, and kitchen stoves, and space heaters to the outside can significantly reduce mold issues in these areas. Also, it helps to store firewood outdoors — storage of one cord of green firewood indoors over the winter can produce the same amount of moisture as does a family of four through respiration!
Your air conditioner acts as a dehumidifier after it runs for about eight minutes. Use this to control relative humidity on an ongoing basis, Install your hygrometer right next to your thermostat to constantly monitor your home.
Some people use dehumidification to remove moisture from a space; the dehumidifier warms the moisture-laden air to reduce its ability to hold moisture, thereby forcing moisture to condense. This can be helpful in the short term, but you should also control moisture sources to limit interior moisture levels. In other words, fix basement plumbing and leaks, avoid porous absorbent material like cardboard or newspaper in the basement, use and remove carpets and rugs from cold floors, and remove obstacles obstructing air flow in damp areas that can give molds a place to grow.
Consider using a hygrometer to monitor humidity levels, to help you maintain a healthy 30 to 55 percent humidity. If you find moisture levels are too low, you can counter the low humidity by reducing ventilation or you can use a humidifier, cleaning it often and monitoring the humidity level.
Now that you understand how your home’s renovation impacts world energy, world resources, and the health of you and your family, you have a solid background for changing the world, one room at a time....