Friday, September 5, 2014


What’s in your attic?  Who cares?  It’s out of sight, out of mind.  It doesn’t get down here where we are!  Or does it?

What’s up there?


First of all, what IS up there?  Probably insulation – fiberglass batting or blown in insulation that probably includes fiberglass and other processed materials including paper and other cellulose-containing matter that has been treated with a fire retardant material.

Fiberglass is primarily considered an irritant to eyes, skin and respiratory system, but has been labeled a possible carcinogen. 

Blown-in insulation has been in use since the 1920’s.  Today it often includes some fiberglass, but post consumer newspapers, magazines or corrugated cardboard.  Since much of this material is flammable, it is treated fire-retardant chemicals.  Reportedly additional components can be Ammonium Sulfate, Boric Acid and a variety of other chemicals, including a variety of biocides to help control some pests and/or fungi and bacteria.

The variety of materials that make up blown-in insulation have not been specifically studied in terms of health effects that I am aware of.  But the chemicals and very small particulate could very well be problematic at least with chronic exposure. 

According to the Central Pollution Control Board, “The human nostrils filter out 99% of the inhaled large and medium sized particles.  The rest may enter the windpipe and lungs where some inhalable particulates cling to protective mucous and are removed.  Some of the smallest particles, called respirable particulates may tend to be deposited in the alveoli (tiny air sacs in the lungs).  In the lungs, particulates slow down the exchange of oxygen with carbon dioxide in the blood, causing shortness of breath.  The heart gets strained, because it works harder to compensate for oxygen loss.  Usually, people most sensitive to these conditions have respiratory diseases like emphysema, bronchitis, asthma or heart problems.  Particulates themselves may be poisonous if inhaled, damaging remote organs like the kidneys or liver.  Swallowed mucous that is laden with hazardous particulate matter may damage the stomach.”

Acute exposure to insulation, e.g. going up into the attic and poking around without a mask, can often result in some short term symptoms like scratchy throat, some irritation or tightness in the lungs, watery eyes and possibly itchy skin, but long term effects from such an acute exposure are unlikely.

Rats and mice:

Rodent infestation or just a family or two residing in an attic is not unusual.  Humans have been virtually or actually cohabitating with rodents for centuries.  That rodents can be responsible for causing or spreading diseases to humans is pretty well known.  Even after the unwelcome guests have been removed, what they leave behind can still cause health problems.

Even if they are in our attic, we don’t worry too much about being bitten by a rat or mouse.  If we are bitten the main problem we need to be concerned with is being treated for rabies. 

Of more concern is the number of diseases that can be caused by exposure to rodent urine or feces as well as other remains like saliva, hair, skin.  The most infamous of these diseases is the Hantavirus.  This is a notorious disease that can be deadly.  The exposure is generally by inhalation of these rodent byproducts.  It has been established that this virus is spread by certain field mice in the southwestern portion of the United States.  There are indications that the virus has been spreading north and possibly to other rodents.  Therefore, it would be possible, though unlikely, to contract the disease from rodent nests in your attic.


Infestation of an attic with birds can also present potential health problems.  Like with rodents, the droppings and other remains can harbor potentially disease provoking microbes.  And like with rodents these diseases can be contracted by inhaling dried feces that were infected with certain fungi.  Generally the droppings become infested with fungi when it remains wet or damp for some period of time due to being shaded sufficiently or by some other phenomena that prevents it from become dried out in a relatively short period of time.  The fungal spores remain in the material after it has dried out and when airborne can infect a person inhaling them.

The two major diseases caused by bird debris are Histoplasmosis and Cryptococcosis.  Both are serious illnesses if not treated.  Persons with weakened immune systems can be subject to systemic infections.


We can hardly submit an article concerning indoor air quality without considering mold in the mix.  Ceiling constructed of drywall are especially susceptible to mold growth.  Even a small roof leak that goes unnoticed for long periods of time can result in mold growth that can contribute to the overall air quality problems in the attic.  Water leaking from the roof into the insulation will run down to the ceiling and being covered by the insulation will not dry out quickly making mold growth more likely.

If the roof leak does not produce sufficient water to cause it to soak through the drywall thereby producing water stains visible from below, mold growth there will go unnoticed.  If the roof leak becomes more pronounced, water stains will show up below and then the problem is likely to be addressed.  If not, it’s out of sight and therefore out of mind.  With no activity in the attic, that is probably true, but activity in the attic that disturbs the insulation there can result in the various particulate, including mold spores to become airborne.

How does it get here from there?

Recessed lighting:

Most recessed lights provide a direct air pathway between the attic and the occupied space below.  This is particularly the case with older lights.  Some of the newer ones have very little if any penetrations through the light fixture that would allow airflow.  However, many older houses have lights that can present a real air infiltration problem.  This potential problem was supposed to be mitigated by requiring that recessed lights have 12 inches around them with no insulation.  Of course the problem with this is that this only lasts as long as there is no activity in the attic by workers, inspectors, installers, rats, mice, birds or wind.  Disturbance of materials in the attic causes potential contaminants to become airborne and with the air pathway between the attic and occupied space, can result in exposure.

HVAC closets:

Many older houses have closets inside that house the air handler that serves the house.  I have seen many that have a large hole in the closet ceiling that goes directly to the attic.  Sometimes there is a screen to keep chunks of insulation from falling into the closet, but not all the time.  And screen or not, this is a direct air pathway from the attic to the occupied space whenever the closet door is opened or when there is sufficient wind to positively pressurize the closet to the rest of the house. 

Ventilation ducts:

Most ducts that run through an attic area what are known as “flexible ducting.”  These are ducts constructed of layers of plastic or vinyl with fiberglass insulation between inner and outer layers along with spiral wire that enables the duct to maintain its form and adds strength.  Flexible ducts are relatively inexpensive and easy to install. 

There are two ways I can think of that flex ducts can become a pathway for contaminants from the attic.  And these are both situations I have experienced in some of my inspections of both residences and commercial buildings.  The first situation would be considered worker error, or better sloppy or uncaring workmanship.  Installing flex ducts requires removing the ducts of needed sizes from the boxes or containers they come in and laying them out prior to connecting them.  If care isn’t taken when the sections are being laid out, they can lie in the insulation resulting in insulation getting inside the ducts either by them just carelessly being thrown down or by activity of moving around placing or installing ducts.  When this potentially contaminated material is inside the ducts it can blow out into the occupied spaces for a very long time.  The second possibility concerns rats.  During the summer rats might prefer a cooler environment for their nest or in the winter warm and cozy is a better choice.  Rats are quite capable of chewing holes into these ducts and I have seen numerous instances of just that.  So now you have one or more rats’ nests directly in your air stream with the insulation and other nesting material and all the rat byproducts.  Not a good situation.



What can be done about it?


Certainly there are very elaborate steps that can be taken to eliminate or severely reduce exposure to contaminants in the attic, but I prefer to suggest simple solutions if possible.


I’m not fond of fiberglass insulation and even less so of the blown-in type, but if you have it and don’t want to go to the expense of having it removed and replaced with something a bit more human friendly, you need to isolate the area as much as possible.


Recessed lighting – Older recessed lights can be replaced with new ones that do not have the air pathways of the older ones.  That can get a bit expensive, particularly if you have a lot of them.  An alternative that would not eliminate the potential for contamination, but would reduce it is to build boxes that would equal 12 inches surrounding the recessed lights.  Make sure the height of the box is sufficient to keep insulation from falling into the box.  Such a barrier will help. 


A second step that can be taken is to have an outside air intake installed on the HVAC system.  Bringing in sufficient filtered outside air via the HVAC system pressurizes the house from air infiltration from outside as well as from such areas as basements and attics.  This will reduce if not eliminate the airflow from the attic into the occupied spaces.


HVAC closets – Bringing in outside air via the HVAC system will help eliminate this source as well.  The only purpose I can see of the hole in the ceiling of the HVAC closet is for ventilation purposes.  It should be fairly simple to run a duct from the closet to the roof to vent out heat when needed.  With that there is no reason to have an air pathway between the attic and the HVAC closet.

Ventilation ducts – If rats are the problem, get an exterminator to rid your residence of them and to provide simple actions to keep them out.  Ducts that have become compromised need to be removed and replaced.  If there are no rat holes and nests in the ducts, they can be cleaned to National Air Duct Cleaners Association (NADCA) standards.  It would be prudent to have the air handler cleaned at the same time.

After word:


To wrap it up I want to say that I am not one to paint “gloom and doom.”  Many people who are generally in good health will not be particularly affected by exposure to a bit of contamination.  It can be argued that people raised or kept for long periods of time in pristine environments can become very susceptible to contaminated environments where those who have confronted contamination from time to time already have built up resistance are more likely to be unaffected or minimally affected. 

What I advocate is that we observe and educate ourselves so we can control our personal environment and that of our family or coworkers in the case of the work environment.  With that we can take the necessary steps to improve our living environment as needed for our benefit and that of those around us.


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