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This article discusses methods to check a building for animal allergens (cat, dog, etc) using as an example, Cat Dander: how to inspect and test a building for past or current presence of cats, cat hair, cat dander, and cat allergens.

This website provides information and procedures for finding, testing, cleaning and preventing indoor mold, toxic black mold, green mold, testing building indoor air quality, and other sick house / sick building investigations. Here are research articles, inspection and testing procedures, and contact information for expert services. At ALLERGENS in BUILDINGS, RECOGNIZING we discuss and provide photos of common indoor allergenic particles found in homes and in the work place. At ALLERGEN TESTS for BUILDINGS we discuss testing buildings for the presence of animal allergens or other allergens such as insect fragments or fecals. Also see  ANIMAL ODORS IN BUILDINGS for suggestions about removal of pet odors.

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Why Test for Animal Allergens Indoors?

The following question from a reader about testing for cat allergens in a home prompted our advice on what to do about cats and cat allergens which follows the cat question itself.

I am wondering if you know of or could perform a test in our home to determine the level of cat dander present. We are renting our home to tenants until next summer, but we have been told that the tenants may be keeping/hiding an indoor-only cat for their daughter (although our lease does not allow any pets). Our daughter and I both have severe cat allergies and I do not know

(a) if we can prove that they have a cat and

(b) what if anything we could do after they move out to make the home safe for our daughter and me again. Do you have any suggestions?

How to Inspect for and Test for Previous or Current Animal Presence in a Building

There are several approaches I suggest to look for evidence of a cat (and cat allergens) in a building.

How to Test for Proof that a Cat is or has been in a Building

Here are several easy and inexpensive approaches to testing for the presence of cats in a building:

1. The olfactory or "smell" test for cats: is there a cat-box odor somewhere? Especially in the case you cite, of an "indoor only" cat, a litter box must have been used in the building.
   
   Only the most diligent and frequent cleaning of the litter box and the surfaces around it will prevent any trace of a cat urine odor in that area. If a male cat was present in the building and has urinated or "marked" any surfaces, the smell will be very strong.
   
   Cats are generally clean animals provided the cat is healthy. But their litter box is a common odor source as well as a possible source of pathogens, bacteria, and mites.
   
   
2. The animal hair test for cats: Most cats shed all the time. Somewhere in the building, in particular, where the cat likes to sleep or rest, there will be cat hair concentrated. (This is also a great place to sample for cat dander or cat "allergens"
   
   
3. Cat dander in dust samples: cat dander, skin flakes shed by cats and other mammals, includes proteins (from the cat's saliva) which are allergenic and can be strong irritants to people with cat allergies or perhaps asthma. You can test for cat dander easily using a particle collection and identification approach:
• Settled dust sample collection: collect one or more samples of settled house dust, particularly, in areas where a cat might have been spending a lot of time, or perhaps from an A/C or hot air furnace return register grille which is giving you a long term sample of house air.
  
  Use the adhesive tape sampling method at Six Easy Steps to Get and Mail a Mold Test Kit to a lab for 24-hour turnaround on sample analysis.
  
  Cat dander is visible on microscopic analysis provided the lab has a forensic analyst who is properly trained in animal dander identification. Photographs of cat dander are at our website too.
• Vacuumed dust sample collection: an alterative which you may not be able to do as easily (I use special vacuum sampling equipment), is the collection of a vacuum sample of upholstered or carpeted surfaces in the most-suspect areas.
  
  A do-it-yourself dust vacuum approach has been used to sample dust on carpets and furniture, by using the open end of a vacuum cleaner tube covered by a special filter "sock" which can be purchased for that purpose.
  
  Some of our clients made their own particle collection sock using a square of fine linen (which loses some of the very small particles) or a coffee filter (which worked rather well provided the sample was not overloaded).
  
  
4. Protein assay for cat allergens: There are also chemical assay procedures for animal allergen detection but in our opinion the particle identification approach is faster, less costly, at least as reliable if not more, and permits forming an opinion about the relative level of allergens by noting the dominant particles in the sample. A specific assay for a specific protein or chemical is not going to provide that contextual interpretative data.
5. Use of a "black light" or UV lighting to check for animals in buildings can be a useful tool if you are screening for pet urine. We discuss this too further at   ANIMAL ODORS IN BUILDINGS

Forensic Laboratory Approach to Identification of Cats in Buildings

• Cat Dander in Lab Samples: Some cat dander might be found in almost any building as people bring it in on clothing from other locations. Cat dander can generally be identified in dust samples by its physical characteristics such as size and shape.
  
  Having inspected and performed the lab analysis for many buildings, I'd have an opinion (as would another experienced microscopist), when examining a microscope slide prepared from the dust samples discussed above. With some field and lab experience, the analyst can discuss the probability that the level of cat dander in a sample slide was high enough to suggest that a cat is or was in a building.
  
  
• Cat Hair and Other Animal hair in Lab Samples: similarly, cat hair (as well as dog, rabbit, and other animals, can generally be identified by microscopic procedures.
  
  An experienced analyst can express an opinion regarding the frequency of appearance of cat hair in a building dust or debris sample. Of course cat hair may have been visible and thick in a building. Here I'm discussing the presence of hair fragments in a sample where perhaps cat hair was not visually obvious at the building site.

What to Do About High Levels of Cat Dander, Cat Hair, Cat Allergens in a Building

If we find that there is evidence of a high level of cat dander or other problem allergens in the building dust, we could design a cleaning regimen that can substantially reduce those levels, ranging from discard of materials to HEPA vacuuming to washing certain surfaces. As this can get costly I wouldn't do so unless needed.

We might also suggest some special measures for more ordinary house cleaning such as buying a HEPA-rated house vacuum cleaner, reduction or elimination of wall to wall carpeting, and a regular cleaning schedule.

If there appear to be building related health or allergy complaints after cleaning we can suggest additional measures to reduce the allergen level indoors, and perhaps, (let's hope it's not needed) recommend a more thorough building investigation for other problem sources.

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ALLERGEN TESTS for BUILDINGS
ALLERGENS in BUILDINGS, RECOGNIZING
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
ANIMAL ALLERGENS / PET DANDER
PERSISTENCE of ALLERGNS
CLEANING SUGGESTIONS
DRUGS vs CLEANUP
ALLERGEN DANDER STUDY
PETS AS FAMILY MEMBERS
REDUCING PET ALLERGENS
CAT DANDER
PET ALLERGEN REMEDIES
ENVIRONMENTAL HAZARDS GUIDE
AIR POLLUTANTS, COMMON INDOOR
ALLERGEN TESTS for BUILDINGS
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
FLOODS IN BUILDINGS-priorities
MOLD INFORMATION CENTER
ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD
CLEARANCE INSPECTIONS - MOLD CLEANUP
DO IT YOURSELF MOLD CLEANUP
ENERGY SAVINGS in BUILDINGS
ENERGY SAVINGS PRIORITIES
ENERGY SAVINGS RETROFIT CASE STUDY
ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE
ENERGY SAVINGS RETROFIT OPTIONS
FIND MOLD in BUILDINGS, HOW TO
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INDOOR AIR QUALITY METHODS COMPARED
LEAD POISONING HAZARDS GUIDE
MOISTURE CONTROL in BUILDINGS
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD AGE - Old is the Mold?
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
MOLD APPEARANCE - STUFF THAT IS NOT MOLD
MOLD ATLAS & PARTICLES INDEX
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD REMEDIATION CLEARANCE INSPECTION
MOLD DETECTION & INSPECTION GUIDE
MOLD EXPERT, WHEN TO HIRE
MOLD INSPECTORS & MOLD TESTERS
MOLD PREVENTION GUIDE
MOLD RELATED ILLNESS GUIDE
MOLD RELATED ILLNESS SYMPTOMS
MOLD TEST KITS
ODORS, Smells, Gases in Buildings-Diagnosis & Cure

• Pet Allergens, Asthma, and IAQ: Dog Dander, Cat Dander, and Other Animal Dander - Information for Asthmatics and Indoor Air Quality, provides details about reducing the level of indoor animal allergens.

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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