Hoarding behaviour photograph illustrates fire and building exit hazards from book hoarding © Daniel FriedmanHoarding Hazards
Health, Fire, & Safety Hazards from Hoarding Behaviour in Buildings: too much stuff, too many animals

  • HOARDING HAZARDS - CONTENTS: about health & safety hazards associated with hoarding disorder or with other high-clutter buildings or where extensive animal or pest invasions are present
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Building occupant hoarding & hoarding disorder hazards:

This article describes the hazards found in buildings where there has been a history of hoarding, or occupants with hoarding disorder. The hazards associated with hoarding behaviour include immediate fire or other life safety hazards including trips, falls, and fire traps, as well as possible health hazards from animal-induced bacteria, viruses, mold, or other pathogens.

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Health, Fire & Safety Hazards of Hoarding in Buildings

Book hoarding 40,000 volumes: fire & mold hazards (C) Daniel Friedman Mabbettsville NY 2013Reader Question:

Just took a took of your website. THANK YOU. Lots of information with facts and logic. I found several areas where animal & pet issues are discussed but I didn't find what I was specifically looking for.

[Click to enlarge any image]

I found the analysis of ammonia but it's mostly work related. I found the info on cleaning up pet smells/waste but it doesn't tell when animal urine/waste/stink becomes a health hazard (and the nature of the hazard(s) from smell/urine/waste) and that is what I was hoping to find.

Any chance of talking someone into writing that article on your website? Excessive collection of "stuff" (aka "hoarding") has also become a hot emotional topic. Any chance of an fact and logic based article on the real hazards (toxins, pest invasion, etc.) and the point(s) where they become health hazards as distinguished from the emotional "too much stuff" that isn't hazardous? - Leslie S., 09/06/2014

Our photo at above left illustrates areas in a home occupied by a book hoarder who amassed over 40,000 volumes. We found fire safety, egress, and serious mold hazards at this property as well as other building hazards that accrued from inability to attend to home maintenance, safety and repair. These book hoarding behavior photographs are examples taken from a different building than the one discussed by the reader's question. - Ed.

Reply: Animal hoarding hazards: urine, feces, and related pathogens as a health hazard

Dog urine stains indoors: the perpetrator seems pleased to have left this puddle but the owner was not so happy (C) Daniel Friedman Michelle GilliganExcellent question, Leslie.

However I expect that a determination of the actual level of health hazards from hoarding as well as for invading animals requires an expert onsite investigation as conditions vary enormously from one case to another.

Our photo (left) illustrates the culprit sitting happily by a large puddle of dog urine in a New Jersey home.

But in more serious cases of animal hoarding (excessive pets in a home: 23 cats & 19 dogs, for example), both biological and often other more immediate fire and safe exit hazards are common.

Since 1947 firefighters and mental health professionals have discussed "Collyer mansions", a reference to a fatal fire in 1947 that burned the mansion owned by the wealthy and accentric Collyer brothers.

The Collyer mansion was jammed with an estimated 120-140 tons of stuff - a condition that blocks emergency exit from a building in event of a fire, feeds the fire, and hampers the efforts of firefighters in both controlling the fire and rescuing building occupants.

In general and in my opinion as well as that of health and other agencies with whom I've worked, hoarding behaviour, depending on its extent, can lead to a variety of very serious hazards of which the most common is a fire hazard accruing from both the storing of large amounts of sometimes combustible materials (newspapers for example) and because often the hoarder ultimately is living in a confined space with limited opportunity for safe exit in the event of a fire.

Collyer mansion fire, 1947, shows the dangers of hoarding - orignal: Ed Jackson, New York Daily News The black and white photo at left shows New York City fire officials examining the fatal Collyer brothers fire site in 1947. The photograph was taken by Ed Jackson at the New York Daily News and has been widely published among sets of photographs of the tragic Collyer Brothers hoarding-fire.

Reinisch (2008) gives us some example statistics on animal hoading-related hazards:

Residential home interiors were usually unsanitary, 93%; 70% had fire hazards; and 16% of residences involved in animal hoarding were subsequently condemned as unfit for human habitation. - Reinisch (2008)

That author goes on to point out that

Elderly individuals are at an increased risk for zoonotic diseases due to underlying medical conditions that weaken their immune systems ...

and, addressing your question about the hazards of exposure to ammonia associated with animal hoarding related urine:

There is also a health risk from to ammonia, which at high concentrations causes ocular and respiratory irritation (1,3). The ammonia threshold limit values (TLVs) for a healthy individual should not exceed 25 ppm over an 8-hour period (4).

The TLV is lower if the exposure has exceeded 8 h or if the individual is elderly or has respiratory problems (3). For short-term exposure (15 min), the recommended TLV is 35 ppm (3), while 20 ppm will cause an individual to feel uncomfortable, and 100 ppm will cause irritation of the upper respiratory tract, eyes, and nose (4). There is little information on ammonia levels in animal hoarding cases; however, 1 case reported levels of 152 ppm (5). - Reinisch (2008) & additional citations under Reinisch (see below).

Book Hoarding Hazards: mold contamination, fire hazards, blocked exits, collapsing heavy shelving

You can see examples of those risks in these photographs of a home where the occupant was a book hoarder. The owner, who had died when we inspected this home for his widow, displayed a poster in one of his book rooms, reading "Warning, Rare Book Pox, Highly Contagious, ..."

Book hoarding hazards in a building in Mabbettsville NY (C) Daniel Friedman 2013 Book hoarding hazards in a building in Mabbettsville NY (C) Daniel Friedman 2013

Health hazards from bacteria, mold, viruses, or other pathogens are surely site and site condition dependent. For example a hoarder who also provides a home to 35 cats, or 12 dogs, or whose home is a haven for mice, rats or other rodents faces still another set of pathogenic risks.

Portable UV flashlight can help spot animal urine in or around buildings (C) Daniel FriedmanSee ANIMAL or URINE ODOR SOURCE DETECTION where we discuss using a UV light or "black light" to scan building interiors or exteriors for the locations of animal urine and some other contaminants.

See Barry (2005) for notes on ammonia and health hazards associated with animal hoarding or invasions in buildings.

Gilliam (2011) cites safety hazards associated with hoarding behavior and Schorow (2012) specifically cites hoarding-related fire hazards.

Hoarding Disorder & Pest Invasion

Regarding your question of the relationship between hoarding behaviour and pest hazards, I have not encountered a direct relationship between insect pests and hoarding, though I have found that hoarders are often also unable to attend to basic home maintenance: a condition that means leaks may have gone unattended as well as other building failures (backing up drains, for example).

A result of hoarding disorder may thus include an increased risk of insect attack on the building, rodent invasion, and thus indirectly, even an increase in risk of hanta virus related or other pathogenic-related illnesses, but I cannot substantiate that by research citations. Conicidentally, rodents themselves are hoarders: see Sheikher (1991) in our citations below.

Reader comment:

Thank you for such a wonderful reply. You list the hazards (fire at the top) in the same order I would. I expect it would vary but some objective guidance would be helpful and you've listed sources I'll be reading. However, I also see your first source is Patronek, someone whose research has been entirely funded by animal rights activists, and who has a veterinarian degree and likes to portray himself as a psychologist (an area he seems to have no training in).

I find myself often in debates where I'm in the middle wanting SOME way to analyze and sort fact from fiction. The animal rights activists seem to see any smell in an environment as conclusive evidence of hoarding while the other end of the spectrum things nothing is dangerous. Seems to me the obvious answer lies somewhere between. I look forward to your published results. - L.S. 7 Sept 2014


In discussing indoor ammonia exposure hazards, Reinisch (2008) cites the 6th Edition of the Documentation of the Threshold Limit Values and Biological Exposure Indices. ACGIH; Cincinnati, Ohio: 1996. American Conference of Governmental Industrial Hygienists: Ammonia.

It would be relatively easy to make actual ammonia level exposure measurements in a building, and to compare these with ACGIH standards. In my experience there is usually a very wide gap between unpleasant stains or even odors from even well-cared-for household pets such as Rudi the golden retriever in my photograph above, and the very different and egregious animal hoarding cases described by experts one finds in the literature. There would be no rational defense of a claim that Rudi's home showed evidence of animal hoarding nor that Rudi was being treated cruelly.

Regarding your remarks about Patronek VMD, PhD, (Cummings School of Veterinary Medicine at Tufts University) et als, those citations and their funding are commented-on below. It would in my opinion a bit of a stretch and perhaps unjust to equate the supporting trusts cited with more radical and sometimes less than rational activists (e.g. the Animal Liberation Front, sometimes equated at least by search results with "econterorism") suggested by your comment.

Research on Health, Fire & Life Safety Hazards Associated with Hoarding


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