September, 2007
Inspection News and Views from the American Society of Home Inspectors

Don't Crawl Naked: Protect Yourself from Airborne Contaminants


In Virginia, there are a lot of homes built over crawl spaces, and having been a home inspector for 11 years,
I have seen the good, the bad and the downright ugly when it comes to crawl spaces.

Now, I hear inspectors in places like Florida and Texas don’t see many crawl spaces, but if you inspect attics or under structures, my story may still be of value to you.

Three years ago, I was diagnosed with a form of cancer called Multiple Myeloma, an incurable malignant cancer of the blood plasma cells in the bone marrow. This cancer is not hereditary, and the cause is unknown. Some studies have shown certain occupations such as firefighters, painters, petroleum workers and farmers with a slightly higher incidence of this disease than the general population. The common link with these groups is the inhalation of chemicals.

Since I’ve never held any one of these jobs, I couldn’t see where any of this fit with my situation until I found out about the farmer. It seems that out of the four mentioned occupations, home inspectors are best grouped with farmers. It is believed that farmers experience the higher incidence of cell damage because they handle a lot of pesticides and herbicides. Not only are they exposed when mixing, spraying, and handling the pesticides, they breathe dust that has been contaminated with these chemicals while plowing their fields.

See the particles as you exit

Breathing dust that has been contaminated with pesticides is something many home inspectors do on a daily basis. For eight years, I crawled through crawl spaces without any breathing protection, as I suspect many of you do today. Any inspector who has crawled into a crawl space knows that most of the exposure occurs on the trip out. I use a strong professional flashlight. My personal preference is the UltraStinger, which cuts a sharp, white beam of light through a crawl space. It’s on the trip out that I can see in my light beam all the dust particles I stirred up on my way in.

Even in newer homes that have polythylene vapor barriers on the floor of the crawl space, there are still some risks. Trust me, the insulation contractor did not vacuum the plastic-covered floor after he tore open the batts of fiberglass insulation down there and stuffed them up between the floor joists. All of those loose glass fibers now lay on top of the plastic sheeting forever, never to biodegrade, just waiting to become airborne. Even though fiberglass is classified only as a possible carcinogen, common sense would seem to tell us that breathing microscopic glass shards into the lungs is not good for our health. The risk might be slight for a homeowner who enters an attic or a crawl space once a year, but we home inspectors do this on a daily basis. It’s the cumulative exposure over a period of years that can do real harm.

Contaminants build up in old dirt

It’s in the older homes with dirt-floor crawl spaces where we face real dangers. Older crawl spaces have no plastic sheeting to cover the dirt, and that dirt is old dirt. It has a distinct odor that can permeate your inspection clothes, even through your coveralls. That smell is a combination of contaminants in the soil. Crawl spaces in the range of 40-100 years old have been exposed to many years of contaminants from mold spores, decomposed animal carcasses, rodent feces and urine to insulation, which in these older homes can include asbestos.

Known cancer risk

However, it’s the pesticides that can do real bodily harm, especially with repeated exposure, such as home inspectors are subject to almost daily. Older homes may have been treated with pesticides time and again, often using compounds now banned by the government. Banned pesticides such as Chlordane and Dursban were used for years in homes, both commercially as termicides, as well as sold to homeowners for general insect control. Chlordane was an approved termicide from 1947 until1988, when it was banned, and Dursban was banned in the year 2000.

There is a known cancer risk with both of these products. Chlordane can remain active in soil for more than 20 years, possibly longer in crawl spaces. Crawl spaces are like the ancient pyramids in that what’s inside is protected from the elements. Archeologists have found grain in pyramids that could still be milled into flour. UV rays of the sun can biodegrade almost anything, but in crawl spaces, there is no sunlight. Rain can leach out contaminants in soil, but there is no rainfall in a crawl space. Wind can blow soil away over time, but the air is always still in a crawl space. What’s more, these pesticides were designed not to biodegrade.

Rodent alert

And that’s not all. In 1993, the Centers for Disease Control and Prevention (CDC) recognized Hantavirus pulmonary syndrome (HPS), a disease that can be contracted when humans come into contact with infected rodents or their saliva, urine and droppings. Although rare, HPS is potentially deadly. It can infect humans who breathe virus-contaminated dust or disturb nesting material, such as moving insulation aside to look at deteriorated floor framing.

If you’re not concerned about what you have read so far, I hope it’s because you already wear a breathing apparatus when you enter crawl spaces. But I suspect that the majority of home inspectors still inspect crawl spaces without adequate safeguards. Sure, you wear coveralls, gloves, kneepads and hats, but what about covering up your nose and mouth? Too many home inspectors are missing the boat when it comes to job safety and protecting our most important asset, our health. Lose your health and you’ve lost your job, and, if you’re a one-person operation, everything could be lost.

Protect yourself

How can we best protect ourselves when entering crawl spaces and attics? In most cases, attics can be entered with a NIOSH-rated N-95, double-strap mask, unless you N95-mask.gifsee evidence of rodents, asbestos and especially pour-in vermiculite insulation, which can contain a form of asbestos called tremolite. Today, I will not enter an attic with vermiculite, even if I am wearing an approved asbestos cartridge on my respirator. I could cross-contaminate the home when getting out of the attic with the stuff on the bottom of my shoes or on my clothing.  Photo: NIOSH-rated N-95 double strap mask.

However, your N-95 dust mask will not cut it when entering dirt crawl spaces. This is where you will need 3M-Mask.gifheavy-duty protection. My inspectors must wear a respirator when entering a crawl space. We wear a half mask with the P-100 purple cartridge. In my opinion, the P-100 cartridge is the best all-around protection for home inspectors. The filter.gifchoice between a full mask or a half mask is a personal one. Beards cause the mask to be less effective, so being clean-shaven is always best. However, if you are like me and can’t part with your beard, keep the beard trimmed close, and wear the mask tight, keeping clean cartridges on the mask at all times. Just like an HVAC return, the mask will start drawing air from other places if the filter is plugged, and that air will be unfiltered.  Photos: Top: 3M™ respirator 600 series, shown without cartridge; Bottom: 3M™ P-100 cartridge.

Not all respirators are created equal

When you decide to use a respirator, it’s important to do your research so you choose one that will provide the
appropriate level of protection and is comfortable to wear. The National Institute for Occupational Safety and Health (NIOSH), part of the CDC, is one source for information. It publishes a Respirator Fact Sheet covering the basics of what is needed for a respirator to provide protection.

The comfort level and fit will be different with each respirator. The fit is the most important factor, because you will need a good seal to best protect you from the environment of the contaminated space. If you live in a large metropolitan area, I encourage you to visit a professional equipment supply store so you can try on several different models. Otherwise, you may have to shop online or by catalog.

Soon, it’s second nature

If you have been crawling around for years without a mask, be forewarned: Wearing a respirator in a tight crawl space will take some getting use to. In time, it will become second nature, and you will not want to enter these spaces without one.

Put this at the top of your to-do list, and go out and get yourself some protection. Your life may depend on it.


Learn More About Choosing and Using a Respirator

CDC Respirator Fact Sheet 2003-144
The National Institute for Occupational Safety and Health (NIOSH), part of the Centers for Disease Control and Prevention (CDC), published a fact sheet for employers and consumers who are considering purchasing escape hoods or other respirators to protect them against potential terrorist threats.

The fact sheet is equally useful for those who are seeking information about respirators for other reasons.
According to NIOSH, “Training is extremely important in regard to the storage, maintenance, use and disposal of the respirator,” and the fact sheet provides suggestions on how to get this training.

In a question-and-answer section, NIOSH explains that not everyone can use a respirator. “Breathing through a respirator is harder than breathing in the open air. People with lung disease, such as asthma or emphysema, elderly people and others may have trouble breathing. Some people with claustrophobia may not be able to wear a mask or a hooded respirator. Some people with vision problems may have trouble seeing while wearing a mask or hood. There are special masks for people who need glasses.”

There also is a list of questions that always should be asked when purchasing a respirator. 

The document is available for free download: or contact NIOSH at 800-356-4674.

Guide on Respiratory Protection Against Bioaerosols – Recommendations on its selection and use

The Occupational Health and Safety Research Institute (IRSST) published the English version of this guide on respiratory protection against bioaerosols.

Bioaerosols are extremely small living organisms or fragments of living things suspended in the air, such as viruses, bacteria, dust mites, molds, fungi, spores, pollen, fragmented particles from insects and by-products of living things (e.g., animal dander, insect excrement).
The objective of this document is to guide in the selection of respirators that protect against bioaerosols in hazardous situations for workers in different sectors: hospitals, household waste-sorting centers, wastewater treatment centers, agriculture, food and beverage processing, etc.

The document first includes a brief description of respirators, air-filtration mechanisms and the assigned protection factors for respirators, completed by information on their fit, seal and care. It then presents the respiratory protection required for infectious and non-infectious bioaerosols.

At the end of the document are a few examples on the choice and use of respirators for various work contexts. The appendices contain a decision tree for selecting a respirator that protects against bioaerosols, as well as the current standards and regulations.

The document is available for free download:

OSHA provides guidance
While the Occupational Safety and Health Administration’s Respiratory Protection regulation (Standards-29 CFR-1910.34) spells out in detail the responsibilities of employers regarding employee respirator use, OSHA also publishes a general information bulletin.

“General Respiratory Protection Guidance for Employers and Workers” provides basic information to workers and employers who may find themselves using respiratory protection for the first time. It explains what respirators are, how they work and what is needed for a respirator to provide protection.

The document is available for free download:

More about asbestos
For information about asbestos, visit: