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This article describes the accuracy and limitations of allergy tests and allergy exposure tests on humans. At ALLERGY TESTS for PEOPLE we discuss the types of allergy and allergy exposure tests used for humans.

At ALLERGENS in BUILDINGS, RECOGNIZING we discuss and provide photos of common indoor allergenic particles found in homes and in the work place. Also see CAT DANDER in buildings. Where toxic, pathogenic, or allergenic mold is a concern in buildings, see MOLD DETECTION & INSPECTION GUIDE and MOLD EXPERT, WHEN TO HIRE.

During building air quality inspections we often find evidence of un-recognized problematic mold reservoirs, or prior occupancy of cats, dogs, mice, birds, and other animals who have been frequently present in a home even though the human occupants didn't know it.

Limits of Allergy Exposure & Allergy Sensitivity Testing Mean Building Tests May Be Appropriate in Some Cases

OPINION-DJF: Above at Skin Testing for Allergies and again at Immunoassay Allergy Testing we noted a few accuracy, false positive, and false negative concerns with allergy testing. While those tests have been used successfully by experienced allergists literally millions of times, they are not foolproof. Summarizing:

False positive allergy tests: Some types of skin tests for allergies can give a false positive result, suggesting that a person is allergic when they have not reacted to the material in the environment

False negative allergy tests: Skin tests for allergies, while they cover a very broad range of foods, grasses, pollen, trees, animals, and even some molds, do not and cannot test for all of the possible allergens and allergen sources in the environment nor in buildings. Furthermore, Sheryl B. Miller and others have raised questions about the actual accuracy of ELISA test results and about the absence of a comparative standard.

Human sensitivity to specific allergens varies widely: while there is no simple standard for acceptable exposure level for allergens, such as molds, there are commonly accepted rules of thumb or general exposure levels. See MOLD EXPOSURE STANDARDS for example of mold exposure standards around the world, and for a list of reasons why a simple mold exposure standard would be technical nonsense. Most IH and mold experts agree that low levels of problematic molds (toxic, pathogenic, or allergenic molds) in the hundreds of spores per M³ of air are not considered a "mold-contaminated" environment.

Yet we have instrumented and actually measured individuals and their environments to demonstrate that some people who are hypersensitive to mold or other environmental irritants can experience severe allergic reactions to very low levels of the problem material. For example, a client who was very mold-sensitive had difficulty breathing in minutes when exposed to airborne Pen/Asp spores at just 600 spores M³ in her home - a level well below that usually defined as "mold contaminated" in buildings.

Human sensitivity to allergens can change over time: some people who suffer chronic exposure to mold or other indoor irritants can become hyper sensitized, subsequently suffering severe reactions to much lower exposure levels than normal. The author (DJF) developed hypersensitivity to Memnoniella echinata (a close relative to Stachybotrys chartarum) following high exposure during a series of building investigations.

Animal allergens and molds are ubiquitous at low levels in buildings and sometimes are present at much higher levels than a simple visual inspection would suggest. For example, mold contaminated building insulation can form a significant problem mold reservoir but might look "clean" to the naked eye. See INSULATION MOLD for details.

We can find at least some animal dander, dog, cat, and mouse, nearly everywhere. Experience with seeing levels in dust from various buildings may be helpful in interpreting those findings.

Human exposure to any indoor contaminant is very difficult to quantify: because people are complex organisms with varying body mass, respiration rate, health vulnerabilities, etc. and because building conditions that affect the level of airborne or other contaminants vary widely often from minute to minute, it is very difficult, often cost-prohibitive to attempt an accurate estimate of the actual exposure to indoor contaminants experienced by a specific person.

At MOLD TESTING METHOD VALIDITY we offer examples of causes of high variability in indoor particle or other contaminant levels - conditions that make airborne measurements and other indoor air quality samples inaccurate. Also see MOLD LEVEL IN AIR, VALIDITY.

Most IH and building environmental consultants take a simpler approach: if inspection or testing detect a large reservoir or problem material in a building, such as a large mold reservoir, that material should be removed, the area cleaned, and the cause of its occurence should be corrected. See MOLD CLASSES, HAZARD LEVELS and also MOLD EXPOSURE STANDARDS.

Building Particle Screening Surveys for Evidence of Allergens, Molds, Other Particles

In general we do not recommend mold testing nor allergy screening in all buildings as a general practice and certainly not where the visible mold or allergen problem is small in size (less than 30 sq.ft. of contiguous problem material). Ordering environmental inspections and tests or high-cost environmental cleanup work when they are not justified is unethical and wastes consumers's money and laboratory operators' time.

But when there are building related occupant complaints, occupants at high risk, or on advice from a physician, there may be a place for simple dust screens for the presence of visible animal dander and visible animal hair. But if you are ordering a lab test of indoor particles to determine an estimate of the level of detectable animal allergenic particles, be sure that the lab will identify the actual particles such as dog dander, cat dander, insect fragments, animal hair, or even specific kind of animal hair (dog, cat, rodent, etc.) Some laboratories simply give a "skin cell" count that includes human skin cells - a useless result.

See MOLD EXPERT, WHEN TO HIRE for advice on determining when it is appropriate and justified to order inspections and tests of a building for mold or allergens.

Check With Your Doctor About Allergens and About Whether or Not Building Tests for Allergens or Mold are Recommended

Of course since individual sensitivity to allergens varies, we suggest that anyone suffering from allergies and considering steps to further clean their home should also consult with their allergist and their general physician.

• SAFETY WARNING: if indoor air quality complaints include respiratory distress, headaches, nausea, and similar symptoms, it is important to immediately rule out unsafe heating equipment, chimneys, flues, or carbon monoxide hazards. See CARBON MONOXIDE & GAS HEAT ODORS.
• The types, accuracy, and variability of human tests for allergy sensitivity and allergy or mold exposure are discussed further at ALLERGY TESTS.
• The combination of allergy testing limitations and occupant complaints that may in some cases justify a building survey for physical particles or other evidence of significant levels of problem allergens, molds, or other conditions is discussed at ALLERGY TEST LIMITATIONS.
• See MOLD EXPERT, WHEN TO HIRE for advice on determining when it is appropriate and justified to order inspections and tests of a building for mold or allergens.
• See Biological Pollutants for information about recognizing and removing these indoor contaminants.
• See ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY for our full list of environmental hazard identification and remedy related to buildings.

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ENVIRONMENTAL HAZARDS GUIDE
ALLERGEN TESTS for BUILDINGS
ALLERGENS in BUILDINGS, RECOGNIZING
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
ANIMAL ALLERGENS / PET DANDER
  PERSISTENCE of ALLERGENS
  CLEANING SUGGESTIONS
  DRUGS vs CLEANUP
  ALLERGEN DANDER STUDY
  PETS AS FAMILY MEMBERS
  REDUCING PET ALLERGENS
BOOKSTORE - ENVIRONMENTAL
BUYERS GUIDE - home inspections for mold
CAT DANDER
INDOOR AIR QUALITY & HOUSE TIGHTNESS
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• MedicineNet.com provides a detailed definition of ELISA at www.medterms.com/script/main/art.asp?articlekey=9099
• "IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
  The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
  http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue butinterestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
• Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
• WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• Environmental Health & Investigation Bibliography - our own technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
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More Information on Building Diagnostic Inspections and Repairs

More Reading: specific to topics discussed in this document:
What indoor humidity should we maintain in order to avoid a mold problem?
Air Conditioning System Blower Fans & Filters Cascading for Optimum Indoor Air Quality The Use of Ozone Indoors for Control of Odors and Mold Removal in Buildings: A Summary of Hazards and False Claims.

• Allergen Tests in Buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
• Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
• Atlas of Mold Related Illness Symptoms & Complaints - incredibly long list
• Cat Dander: how to inspect and test a building for past or current presence of cats, cat hair, cat dander, and cat allergens
• Clinical Atlas of Mold Toxicity - An Online Description of Toxic, Pathogenic, Allergenic Fungi, Fungal Diseases
• Fiberglass Insulation Contains Mold© 2005 comments about a field study in process, & more about health hazards from fiberglass insulation - DJF
• Odors, Odor Detection, Smells, & Gases how to find and identify sources of noxious or toxic odors and gases
• Other environmental risks, Our much longer list: Asbestos, carbon monoxide, electromagnetic fields, etc.
• Pollen Allergens: identification,
• Products to Reduce Mold & Allergy Problems to reduce indoor mold or allergen levels: air cleaners, air purifiers, dust mite covers, vacuum cleaners, crawl space vents
• Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
• Rodent control issues, including dander, fecal, and urine contamination of Buildings and Building insulation are discussed at our Mold Action Plan page.
• Sewage and Septic backup contamination in Buildings: inspection, testing, remediation, & references to expert sources
• Action Guide: What to do about mold, mildew, and other indoor allergens

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