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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
AIR CLEANER PURIFIER TYPES
AIR POLLUTANTS, COMMON INDOOR
AIR QUALITY IMPROVEMENT STRATEGIES
AIRBORNE PARTICLE ANALYSIS METHODS
ALLERGEN TESTS for BUILDINGS
ASBESTOS IDENTIFICATION IN BUILDINGS
BACKDRAFTING HEATING EQUIPMENT
BLACK MOLD, TOXIC & ALLERGENIC
BLEACHING MOLD, Advice about
BOOKSTORE - ENVIRONMENTAL
CADMIUM in the HOME
CARBON MONOXIDE - CO
CARPETING & INDOOR AIR QUALITY
CAT DANDER in BUILDINGS
CELL PHONE RADIATION
CHEMICAL CONTAMINANTS in WATER
COMBUSTION PRODUCTS & IAQ
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
DUST SAMPLING PROCEDURE
EMERGENCY RESPONSE, IAQ, GAS, MOLD
EMF ELECTROMAGNETIC FIELDSRE
ENDOCRINE DISRUPTERS at BUILDINGS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOR TILE ASBESTOS IDENTIFICATION
FUNGICIDAL SPRAY & SEALANT USE
GAS EXPOSURE EFFECTS, TOXIC
HEATING OIL EXPOSURE HAZARDS, LIMITS
HOUSE DUST ANALYSIS
HOUSE DUST COMPONENTS
HUMIDITY CONTROL & TARGETS INDOORS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
LAB PROCEDURES MICROSCOPE TECHNIQUES
LEAD POISONING HAZARDS GUIDE
LEGIONELLA LEGIONNAIRES' DISEASE
LIGHT, GUIDE to FORENSIC USE
METHANE GAS SOURCES
MILDEW in BUILDINGS ?
MOISTURE CONTROL in BUILDINGS
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD CONSULTANTS / INSPECTORS
MOLD DETECTION & INSPECTION GUIDE
MOLD EXPERT, WHEN TO HIRE
MOLD RELATED ILLNESS GUIDE
MSDS Material Safety Data Sheets
MVOCs & MOLDY MUSTY ODORS
NOISE / SOUND DIAGNOSIS & CURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
OIL, HEATING, EXPOSURE HAZARDS, LIMITS
OIL HEAT ODORS & NOISES
OIL SPILL CLEANUP / PREVENTION
PET ALLERGENS / PET DANDER
PET STAINS & MARKS in BUILDINGS
PLASTIC ODORS-SCREENS, SIDING
PLUMBING SYSTEM ODORS
PVC - VINYL BUILDING PRODUCTS
RADON HAZARD TESTS & MITIGATION
SAFETY HAZARDS GUIDE
SAFETY HAZARDS & INSPECTIONS
METHANE GAS HAZARDS
SEPTIC SYSTEM ODORS
SEWAGE BACKUP TEST & CLEANUP
SEWER GAS ODORS
SMELL PATCH TEST to Track Down Odors
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
SULPHUR & SEWER GAS SMELL SOURCES
UFFI UREA FORMALDEHYDE FOAM INSULATION
URETHANE FOAM Deterioration, Outgassing
VINYL CHLORIDE HEALTH INFO
VOCs VOLATILE ORGANIC COMPOUNDS
WATER ODORS, CAUSE CURE
Here we provide a summary of common indoor biological contaminants such as mold, animal dander, pollen, viruses, and bacteria. We explain the requirements to remove these materials to improve indoor air quality and other health conditions in buildings.
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Our page top photo shows an obviously moldy building that needs professional cleaning. But other mold and biological contaminants may be more difficult to spot..
Our photographs above show common sources of indoor biological pollutants including an un-discovered sewage backup in a crawl space (above left) and cockroach fragments and fecal dust (above right).
For help looking for less obvious indoor mold contamination see MOLD APPEARANCE - WHAT MOLD LOOKS LIKE. Also see ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY for our full list of environmental hazard identification and remedy related to buildings
Biological pollutants are or were living organisms. At least some of these are found in every home.
Common examples include molds, pollen, dust mites, animal dander, and cockroaches, as well as viruses and bacteria.
Our photo above shows gross evidence of a sewer backup in a crawl space that was ignored by the building owner, leaving a pathogenic hazards in the building (above left), and a cockroach fragment found in building dust (below left).
Whether these biological hazards and particles are brought in to the building inadvertently by humans or pets or ride along on houseplants or their soil, living organisms tend to stay longer and breed more successfully in warm, damp conditions.
In fact, given temperatures of 50°F to 90°F and a material that stays wet for more than 48 hours, a colony of mold or other fungi will rapidly develop from their invisible spores, which are everywhere in our environment just waiting for the right conditions to spring to life.
Health Effects. Allergic reactions are among the most common health problems associated with indoor air quality. They are often connected with molds, pollen, animal dander (mostly from cats and dogs), and dust mites, which are microscopic animals living in carpets, bedding, and furnishings. Allergic reactions can range from annoying to life-threatening, as in a severe asthma attack. Common symptoms include watery, itchy eyes, runny nose, sneezing, nasal congestion, coughing and breathing difficulties, headaches, and fatigue.
Asthma. Children and adults with asthma are particularly at risk. Asthmatics have very sensitive airways that react to irritants by narrowing, making breathing difficult. Between 1980 and 1994, asthma rates in the United States rose by 75%, affecting over 20 million people today, including over 6 million children, according to the Centers for Disease Control and Prevention.
Our lab photo (left) shows skin cells and dog dander particles, dyed red with acid fuchsin for clarity.
Asthma “triggers” vary from person to person, but some of the most common indoor triggers are biological allergens, such as dust mites; molds; animal dander, urine, and saliva; and cockroach body parts, secretions, and droppings.
At ALLERGENS in buildings, RECOGNIZING we provide additional field and laboratory photographs of common indoor allergens.
Suggestions for Reducing Exposure to Biological Pollutants Indoors
Since most biological pollutants thrive in a moist environment, the key to reducing them is good moisture control. This starts with building houses correctly with good foundation drainage and waterproofing, proper flashings, continuous air and vapor barriers, and adequate ventilation. Household humidity levels should be maintained between 30% and 50%.
Basements should only be finished if they are dry year-round and detailed so finish materials and carpeting are not wetted by capillary action or condensation. If a building sustains water damage for any reason, it is essential that the wet materials be dried or removed within 24 to 48 hours or mold will grow. While wood, concrete, and other solid materials can be cleaned and disinfected, porous materials should be removed and replaced.
HVAC equipment and appliances that come in contact with water are other breeding grounds for biological contaminants. Have all such equipment serviced regularly and keep filters clean. Air conditioners can help filter out pollen, but dirty coils and drain pans can also become a source of biological pollutants. If using humidifiers, clean them according to manufacturers’ instructions and refill with fresh water daily.
Evaporation trays in air conditioners, dehumidifiers, and refrigerators should also be cleaned frequently. Duct cleaning may also be justified if an occupant is suffering from allergies and a visual inspection reveals that the air ducts are contaminated with large deposits of dust or mold. If so, choose a reputable company that follows the standards of the National Air Duct Cleaners Association (NADCA).
Good housekeeping is also an important part of the strategy for controlling household allergens. Bedding should be washed at 130°F. Using a HEPA vacuum or central vacuum with an exterior exhaust is recommended. Minimizing the use of carpeting, upholstered furniture, and dust-collecting shelving and furnishings can also help by eliminating hiding places for dust and contaminants (see CARPETING & INDOOR AIR QUALITY). In some case, portable or central air filtration may also play a role, but these are not a panacea for removing allergens (see Air Filtering Strategies).
-- Adapted with permission from Best Practices Guide to Residential Construction.
Common Sources of Biological Pollutants Indoors
According to the US EPA,
Basic checks for sources of biological contaminants in buildings: Here we provide biological contamination troubleshooting help for buildings by expanded annotated information from the US EPA  who provided suggestions for investigating for biological pollutant sources during an indoor air quality investigation.
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Technical Reviewers & References
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