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AIR CONDITIONING & HEAT PUMP SYSTEMS
ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
ACCEPTABLE MOLD LEVEL
ACCURACY OF VARIOUS MOLD TEST METHODS
ACCURACY vs PRECISION of MEASUREMENTS
ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD
AIR POLLUTANTS, COMMON INDOOR
AIR TEST FOR MOLD: ACCURACY
AIR TEST SAMPLING CASSETTE STUDY
AIRBORNE MOLD COUNT NUMBER GUIDE
ALLERGEN TESTS for BUILDINGS
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
ATTORNEYS and EXPERT WITNESSES
BASEMENT MOLD WATER IMPACT
BROWN HAIRY BATHROOM MOLD
BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ
BOD WASTEWATER TEST
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN OPERATION & TESTING
BLUE vs YELLOW COMBUSTION FLAMES
BOOKSTORE - ENVIRONMENTAL
BUILDING SAFETY HAZARDS GUIDE
Cadmium in the home
CAR MOLD CONTAMINATION
CARBON DIOXIDE - CO2
CARBON MONOXIDE - CO
CACTUS FUNGI / MOLD
CARPET DUST IDENTIFICATION
CARPET MOLD CONTAMINATION
CARPET PADDING ASBESTOS, MOLD, ODORS
CARPET FUNGICIDAL SPRAY
CARPET STAIN DIAGNOSIS
CARPET & other STAIN TESTS
CARPET TEST PROCEDURE
CARPETING & INDOOR AIR QUALITY
CARPETING, SELECTION & INSTALLATION
CLEARANCE INSPECTIONS - MOLD CLEANUP
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
DUCT SYSTEM & DUCT DEFECTS
DUST ANALYSIS for FIBERGLASS
DUST, HVAC CONTAMINATION STUDY
DUST SAMPLING PROCEDURE
EMERGENCY RESPONSE, IAQ, GAS, MOLD
EMF ELECTROMAGNETIC FIELDS & HUMAN EXPOSURE
FIBERBOARD INSULATION SHEATHING MOLD
FIBERGLASS INSULATION MOLD
MOLD in BUILDINGS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FUNGICIDAL SPRAY & SEALANT USE GUIDE
GAS DETECTION INSTRUMENTS
GAS EXPOSURE EFFECTS, TOXIC
GAS EXPOSURE LIMITS & STANDARDS
GAS TEST PROCEDURES
HEATING OIL EXPOSURE HAZARDS, LIMITS
HEATING SYSTEM ODORS
HOUSE DUST ANALYSIS
HOUSE DUST COMPONENTS
HOUSEWRAP AIR & VAPOR BARRIERS
HIDDEN MOLD, HOW TO FIND
HUMIDITY CONTROL TO PREVENT MOLD
HVAC DUST CONTAMINATION STUDY
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INDOOR AIR QUALITY METHODS COMPARED
LEAD POISONING HAZARDS GUIDE
LEED GREEN BUILDING CERTIFICATION
Legionella BACTERIA & HVAC Equipment
METHANE GAS SOURCES
MEDIA BLASTING for MOLD REMOVAL
METHANE GAS SOURCES
MICROSCOPE DIGITAL PHOTOGRAPHY
MILDEW in BUILDINGS ?
MILDEW ERRORS, IT's MOLD
MILDEW REMOVAL & PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD: A COMPLETE GUIDE TO MOLD
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD ACTIVITY in buildings
MOLD AGE, HOW OLD is the MOLD?
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
MOLD APPEARANCE - STUFF THAT IS NOT MOLD
MOLD ATLAS & PARTICLES INDEX
MOLD by MICROSCOPE
MOLD in the PETRI DISH, PHOTOS
MOLD on BOOKS, BOOK CONSERVATION
MOLD CLASSES, HAZARD LEVELS
MOLD CLEANERS - WHAT TO USE
MOLD CLEANUP COMPANIES
MOLD CLEANUP, DO IT YOURSELF
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD CLEARANCE INSPECTIONS
MSDS MATERIAL SAFETY DATA SHEETS
MVOCs & MOLDY MUSTY ODORS
MYCOPHOBIA, STAINS MISTAKEN for MOLD
MYCOTOXIN EFFECTS of MOLD EXPOSURE
NOISE / SOUND DIAGNOSIS & CURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
OIL, HEATING, EXPOSURE HAZARDS, LIMITS
PAINTS & COATINGS ODORS IN BUILDINGS
PARTICLE SIZES & IAQ
RADON HAZARD TESTS & MITIGATION
SAFETY HAZARDS GUIDE
SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SICK HOUSE IAQ QUESTIONNAIRE
SEWAGE BACKUP TEST & CLEANUP
STAIN DIAGNOSIS on BUILDING INTERIORS
STAINS on INDOOR SURFACES, PHOTO GUIDE
SULPHUR & SEWER GAS SMELL SOURCES
THERMAL TRACKING Indicates Heat Loss
THERMAL TRACKING & THERMAL BRIDGING
THERMAL EXPANSION CRACKS in BRICK
THERMAL EXPANSION of HOT WATER
THERMAL EXPANSION of MATERIALS
THERMAL IMAGING, THERMOGRAPHY
THERMAL IMAGING MOLD SCANS
THERMAL MASS in BUILDINGS
TRIM, INTERIOR INSTALLATION
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
VINYL CHLORIDE HEALTH INFO
VINYL SIDING or WINDOW PLASTIC ODORS
VOCs VOLATILE ORGANIC COMPOUNDS
WALL FINISHES INTERIOR
WALL CONSTRUCTION BARRIER vs CAVITY
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in BUILDINGS
WORLD TRADE CENTER 9-11 DUST PHOTOS
What is in house dust? This article discusses analysis of building dust or house dust to trace its origins and to sort out whether or not dust problems are caused by the building HVAC system. A client called about an ongoing dispute with an HVAC contractor who had recently installed new heating and air conditioning equipment and duct work in her home. Mysterious thick "blue dust" was appearing throughout the home, reappearing soon even after vacuuming and cleaning.
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Killer house dust? a case history: Mystery dust identified as cotton, ending dispute with contractor
Our photo illustrates a common finding in house dust, an occasional fungal hyphal fragment along with mostly non-fungal granular debris such as road dust particles. Usual components of house dust include skin cells and fabric fibers. Individual occurrences or infrequent occurrences of individual spores in air or dust samples are usually, but not always, insignificant.
Significance may depend on the context of the investigation. For example we may find low levels of a not-normally-airborne spore such as Stachybotrys chartarum in a building after demolition and remediation during a mold cleanup job - probably not a concern. Finding the same particles in a home that has not been properly cleaned might indicate a need for a more careful investigation.
While there were no serious health complaints nor people at unusual medical risk, the occupants were concerned, and believed that something in the ducts or air handlers was causing a problem.
In contrast, at left we include one of our photographs of analysis of dust from the World Trade Center collapse - not from the building discussed in this article. (See WORLD TRADE CENTER 9-11 DUST PHOTOS).
Now about our client's dust concern, while the dispute had been going on for months, at the time of this call no one had performed a forensic examination of the dust itself. The client mailed me a representative sample of surface dust from the home. Here's one way surface dust can be easily collected and mailed.
We'd be concerned about finding high levels of problematic mold spores, and I'd not like to find a lot of fiberglass in the sample either, both because it may be a health concern and because it'd argue for sloppy work by the contractor.
House dust from an occupied home contains lots of stuff, usually dominated by skin cells and fibers from clothing and upholstery or carpets. Animal dander, particularly from dogs, cats, or mice, may be present at high levels too. In inner-city apartments I find lots of insect fragments as well, possibly cockroach allergens.
And everybody's dust can be expected to have traces of dust mites, usually their fecal pellets. By examining the pellets I can often determine what the mites are eating, for example mold spores.
The dust sample was examined for homogeneity and then prepared for a look at high magnification in my lab, using both ordinary and polarized light, along with special microscope light wavelength filters, and combination of an index of refractive index mounting liquids combined Becke line analysis to measure the refractive index of particles. These methods can quickly separate out synthetic fibers such as Orlon or Nylon, as well as distinguishing typical road grit and fiberglass.
Remarkably the dust sample from this West coast home was unusually clean. The sample was 90% cotton fibers, mostly blue with a few red ones included. There were incidental (not statistically significant) wool fibers present too. Skin cells were another 8% of the sample, and typical drywall dust and road dust made up the rest.
The sample contained no mold spores, no fiberglass, no heating fuel combustion products, no ash, no paint droplets, in other words, it was cotton from a mostly blue fiber source.
This dust source was certainly not from the heating system components.
Without making a site inspection we can still offer some useful speculation:
Look for something new in the home, carpets, drapes, upholstery, bedding,
We would guess that mechanical disturbance like foot traffic, vacuuming, or other activity was combining with air movement from the HVAC system to spread dust around.
Naturally, an investigator is a lot smarter when on-site than when speculating by telephone or email. But in any case, this was the end of arguing with the HVAC contractor who was clearly not at fault.
See CARPETING & INDOOR AIR QUALITY for a broad discussion of indoor air quality concerns regarding carpeting, including chemicals, adhesives, odors, and VOCs associated with carpeting. See DUST SAMPLING PROCEDURE for help in collecting house dust or building dust samples for further analysis.
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