• animal dander (minute scales from hair, feathers, or skin);
• dust mite and cockroach parts;
• infectious agents (bacteria and viruses); and
• pollen.

• allergic;
• infectious; and/or
• toxic.

• watery eyes;
• runny nose and sneezing;
• nasal congestion;
• itching;
• coughing;
• wheezing and difficulty breathing;
• headache; and
• fatigue.

• Does anyone in the family have frequent headaches, fevers, itchy and watery eyes, a stuffy nose, dry throat, or a cough? Does anyone complain of feeling tired or dizzy all the time? Is anyone wheezing or having difficulties breathing on a regular basis?
• Did these symptoms appear after you moved into a new or different home?
• Do the symptoms disappear when you go to school or the office or go away on a trip, and return when you come back?
• Have you recently remodeled your home or done any energy-conservation work, such as installing insulation, storm windows, or weather stripping? Did your symptoms occur during or after these activities?
• Does your home feel humid? Can you see moisture on the windows or on other surfaces, such as walls and ceilings?
• What is the usual temperature in your home? Is it very hot or cold?
• Have you recently had water damage?
• Is your basement wet or damp?
• Is there any obvious mold or mildew?
• Does any part of your home have a musty or moldy odor?
• Is the air stale?
• Do you have pets?
• Do your house plants show signs of mold?
• Do you have air conditioners or humidifiers that have not been properly cleaned?
• Does your home have cockroaches or rodents?

Infectious diseases caused by bacteria and viruses, such as the flu, measles, chicken pox, and tuberculosis, may be spread indoors. Most infectious diseases pass from person to person through physical contact. Crowded conditions with poor air circulation can promote this spread. Some bacteria and viruses thrive in buildings and circulate through indoor ventilation systems. For example, the bacterium causing Legionnaire’s Disease, a serious and sometimes lethal infection, and Pontiac Fever, a flu-like illness, have circulated in some large buildings.

1. Dust and construction materials, such as wood, wallboard and insulation, contain nutrients that allow biological pollutants to grow. Firewood also is a source of moisture, fungi and bugs.
2. Appliances, such as humidifiers, kerosene and gas heaters, washers and clothes dryers, dishwashers and gas stoves, add moisture to the air.

• air-conditioning units;
• basements, attics and crawlspaces;
• bathrooms;
• carpets;
• heating and air-conditioning ducts;
• humidifiers and dehumidifiers; and
• refrigerator drip pans.

What You Can Do About Biological Pollutants

• Fix leaks and seepage. If water is entering the house from the outside, your options range from simple landscaping to extensive excavation and waterproofing. (The ground should slope away from the house.) Water in the basement can result from the lack of gutters or a water flow toward the house. Water leaks in pipes and around tubs and sinks can provide a place for biological pollutants to grow.
• Put a plastic cover over dirt crawlspaces to prevent moisture from coming in from the ground. Be sure crawlspaces are well-ventilated.
• Use exhaust fans in bathrooms and kitchens to remove moisture to the outside (not into the attic). Vent your clothes dryer to the outside.
• Turn off certain appliances (such as humidifiers and kerosene heaters) if you notice moisture on windows and other surfaces.
• Use dehumidifiers and air conditioners, especially in hot, humid climates, to reduce moisture in the air, but be sure that the appliances themselves don’t become sources of biological pollutants.
• Raise the temperature of cold surfaces where moisture condenses. Use insulation and storm windows. (A storm window installed on the inside works better than one installed on the outside) Open doors between rooms (especially doors to closets which may be colder than the rooms) to increase circulation. Circulation carries heat to the cold surfaces Increase air circulation by using fans and by moving furniture from wall corners to promote air and heat circulation. Be sure that your house has a source of fresh air and can expel excessive moisture from the home.
• Pay special attention to carpet on concrete floors. Carpet can absorb moisture and serve as a place for biological pollutants to grow. Use area rugs, which can be taken up and washed often. In certain climates, if carpet is to be installed over a concrete floor, it maybe necessary to use a vapor barrier (plastic sheeting) over the concrete and cover that with sub-flooring (insulation covered with plywood) to prevent a moisture problem.
• Moisture problems and their solutions differ from one climate to another. The Northeast is cold and wet, the Southwest is hot and dry, the South is hot and wet, and the Western Mountain states are cold and dry. All of these regions can have moisture problems. For example, evaporative coolers used in the Southwest can encourage the growth of biological pollutants. In other hot regions, the use of air conditioners which cool the air too quickly may not be left running long enough to remove excess moisture from the air. The types of construction and weather for the different climates can lead to different problems and solutions.

Where Biological Pollutants May Be Found in the Home

• Have major appliances, such as furnaces, heat pumps and central air conditioners, inspected regularly by a professional InterNACHI inspector. Change filters on heating and cooling systems according to manufacturer’s directions. (In general, change filters monthly during use.) When first turning on the heating or air conditioner at the start of the season, consider leaving your home until it airs out.
• Have window and wall air-conditioning units cleaned and serviced regularly by a professional, especially before the cooling season. Air conditioners can help reduce the entry of allergy-causing pollen. But they may also become a source of biological pollutants if not properly maintained. Clean the coils and rinse the drain pans, according to the manufacturer’s instructions, so water cannot collect in pools.
• Have furnace-attached humidifiers cleaned and serviced regularly by a professional, especially before the heating season.
• Follow the manufacturer’s instructions when using any type of humidifier. Experts differ on the benefits of using humidifiers. If you do use a portable humidifier (approximately 1- to 2-gallon tanks), be sure to empty its tank every day and refill it with distilled or demineralized water, or even fresh tap water, if the other types of water are unavailable.  For larger portable humidifiers, change the water as recommended by the manufacturer. Unplug the appliance before cleaning. Every third day, clean all surfaces coming in contact with water with a 3% solution of hydrogen peroxide, using a brush to loosen deposits. Some manufacturers recommend using diluted household bleach for cleaning and maintenance, generally in a solution of one-half cup bleach to 1 gallon of water. With any household chemical, rinse well to remove all traces of chemical before refilling the humidifier.
• Empty dehumidifiers daily and clean often. If possible, have the appliance drip directly into a drain. Follow manufacturer’s instructions for cleaning and maintenance. Always disconnect the appliance before cleaning.
• Clean refrigerator drip pans regularly, according to manufacturer’s instructions. If refrigerator and freezer doors don’t seal properly, moisture may build up and mold can grow. Remove any mold on door gaskets, and replace faulty gaskets.

• Clean moist surfaces, such as showers and kitchen counters.
• Remove mold from walls, ceilings, floors and paneling. Do not simply cover mold with paint, stain, varnish, or a moisture-proof sealer, as the mold may resurface.
• Replace moldy shower curtains, or remove them and scrub them well with a household cleaner, and rinse them before rehanging them.

• Always wash bedding in hot water (at least 130° F) to kill dust mites. Cold water won’t do the job. Launder bedding at least every seven to 10 days.
• Use synthetic or foam rubber mattress pads and pillows, and plastic mattress covers, if you are allergic. Do not use fuzzy wool blankets, feather or wool-stuffed comforters, and feather pillows.
• Clean rooms and closets well.  Dust and vacuum often to remove surface dust. Vacuuming and other cleaning may not remove all animal dander, dust mite material, and other biological pollutants. Some particles are so small, they can pass through vacuum bags and remain in the air. If you are allergic to dust, wear a mask when vacuuming and dusting. People who are highly allergy-prone should not perform these tasks. They may even need to leave the house when someone else is cleaning.

• Have professionals check the heating and cooling system, including humidifiers and vents. Have duct lining and insulation checked for growth.
• Check for exhaust fans in bathrooms and kitchens. If there are no vents, do the kitchen and bathrooms have at least one window in each room? Does the stovetop have a hood vented outside? Does the clothes dryer vent outside? Do all vents exhaust to the outside of the building, and not in attics or crawlspaces?
• Look for obvious mold growth throughout the house, including attics, basements and crawlspaces, and around the foundation outside. See if there are many plants close to the house, particularly if they are damp and rotting. They are a potential source of biological pollutants. Downspouts from roof gutters should route water away from the building.
• Look for stains on the walls, floor or carpet (including any carpet over concrete floors) as evidence of previous flooding or moisture problems. Is there moisture on windows and surfaces? Are there signs of leaks or seepage in the basement?
• Look for rotted building materials, which may suggest moisture or water damage.
• If you or anyone else in the family has a pet allergy, ask if any pets have lived in the home.
• Examine the design of the building. Remember that in cold climates, overhanging areas, rooms over unheated garages, and closets on outside walls may be prone to problems with biological pollutants.
• Look for signs of cockroaches. (Carefully read instructions for use and any cautionary labeling on cleaning products before beginning cleaning procedures.)
• Do not mix any chemical products. Especially, never mix cleaners containing bleach with any product (such as ammonia) which does not have instructions for such mixing.  When chemicals are combined, a dangerous gas can sometimes be formed.
• Household chemicals may cause burning or irritation to skin and eyes.
• Household chemicals may be harmful if swallowed or inhaled.
• Avoid contact with skin, eyes, mucous membranes, and clothing.
• Avoid breathing vapor. Open all windows and doors, and use an exhaust fan that sends the air outside.
• Keep household chemicals out of reach of children.
• Rinse treated surface areas well to remove all traces of chemicals.
  

Correcting Water Damage

• Throw out mattresses, wicker furniture, straw baskets and the like that have been water damaged or contain mold. These cannot be recovered.
• Discard any water-damaged furnishings, such as carpets, drapes, stuffed toys, upholstered furniture, and ceiling tiles, unless they can be recovered by steam cleaning or hot-water washing and thorough drying.
• Remove and replace wet insulation to prevent conditions where biological pollutants can grow.

• Choose vented appliances whenever possible.
• Buy only combustion appliances that have been tested and certified to meet current safety standards. Examples of certifying organizations are Underwriters Laboratories (UL) and the American Gas Association (AGA) Laboratories. Look for a label that clearly shows the certification.
• All currently manufactured vented gas heaters are required by industry safety standards to have a safety shut-off device. This device helps protect you from carbon monoxide poisoning by shutting off an improperly vented heater.
• Check your local and state building codes and fire ordinances to see if you can use an unvented space heater, if you are considering purchasing one. They are not allowed to be used in some communities, dwellings, and certain rooms in the house.
• If you must replace an unvented gas space heater with another, make it a new one. Heaters made after 1982 have a pilot light safety system called an oxygen depletion sensor (ODS). This system shuts off the heater when there is not enough fresh air, before the heater begins producing large amounts of carbon monoxide. Look for the label that tells you that the appliance has this safety system. Older heaters will not have this protection system.
• Consider buying gas appliances that have electronic ignitions rather than pilot lights. These appliances are usually more energy-efficient and eliminate the continuous low-level pollutants from pilot lights.
• Buy appliances that are the correct size for the area you want to heat. Using the wrong size heater may produce more pollutants in your home and is not an efficient use of energy.
• All new wood stoves are EPA-certified to limit the amounts of pollutants released into the outdoor air. For more information on selecting, installing, operating, and maintaining wood-burning stoves, write to the EPA Wood Heater Program. Before buying a wood stove, check your local laws about the installation and use of wood stoves.

To reduce indoor air pollution, a good supply of fresh, outdoor air is needed. The movement of air into and out of your home is very important. Normally, air comes in through cracks around doors and windows. This air helps reduce the level of pollutants indoors. This supply of fresh air is also important to help carry pollutants up the chimney, stovepipe or flue to the outside.

• Keep doors open to the rest of the house from the room where you are using an unvented gas space heater or kerosene heater, and crack open a window. This allows enough air for proper combustion, and reduces the level of pollutants, especially carbon monoxide.
• Use a hood fan if you are using a range. They reduce the level of pollutants you breathe if they exhaust to the outside. Make sure that enough air is coming into the house when you use an exhaust fan. If needed, open a door or window slightly, especially if other appliances are in use. For proper operation of most combustion appliances and their venting systems, the air pressure in the house should be greater than that outside. If not, the vented appliances could release combustion pollutants into the house rather than outdoors. If you suspect that you have this problem, you may need the help of a qualified person to solve it.
• Make sure that your vented appliance has the vent connected and that nothing is blocking it. Make sure there are no holes or cracks in the vent. Do not vent gas clothes dryers or water heaters into the house for heating. This is unsafe.
• Open the stove’s damper when adding wood. This allows more air into the stove. More air helps the wood burn properly, and prevents pollutants from being drawn back into the house instead of going up the chimney. If there is isible smoke or a constant smoky odor inside the home while using a wood-burning stove, this is a sign that the stove is not working properly. Soot on furniture in the rooms where you are using the stove also tells this. Smoke and soot are signs that the stove is releasing pollutants into the indoor air.

• Read and follow the instructions for all appliances so that you understand how they work. Keep the owner’s manual in a convenient place to refer to when needed. Also, read and follow the warning labels because they tell you important safety information that you need to know. Reading and following the instructions and warning labels could save your life.
• Always use the correct fuel for the appliance.
• Use only water-clear ASTM 1-K kerosene for kerosene heaters. The use of kerosene other than 1-K could lead to a release of more pollutants in your home. Never use gasoline in a kerosene heater because it can cause a fire or an explosion. Using even small amounts of gasoline could cause a fire.
• Use seasoned hardwoods (elm, maple, oak) instead of softwoods (cedar, fir, pine) in wood-burning stoves and fireplaces. Hardwoods are better because they burn hotter and form less creosote, an oily, black tar that sticks to chimneys and stove pipes. Do not use green or wet woods as the primary wood because they make more creosote and smoke. Never burn painted scrap wood or wood treated with preservatives, because they could release highly toxic pollutants, such as arsenic or lead. Plastics, charcoal, and colored paper, such as comics and wrapping paper, also produce pollutants. Never burn anything that the stove or fireplace manufacturer does not recommend.
• Never use a range, oven or dryer to heat your home. When you misuse gas appliances in this way, they can produce fatal amounts of carbon monoxide. They can produce high levels of nitrogen dioxide, too.
• Never use an unvented combustion heater overnight or in a room where you are sleeping. Carbon monoxide from combustion heaters can reach dangerous levels.
• Never ignore a safety device when it shuts off an appliance. It means that something is wrong. Read your appliance instructions to find out what you should do, or have a professional check out the problem.
• Never ignore the smell of fuel. This usually indicates that the appliance is not operating properly or is leaking fuel. Leaking fuel will not always be detectable by smell. If you suspect that you have a fuel leak, have it fixed as soon as possible. In most cases, you should shut off the appliance, extinguish any other flames or pilot lights, shut off other appliances in the area, open windows and doors, call for help, and leave the area.