A homeowner is delighted with the well-made details of her mid-1960s house. But there’s a nagging worry in the basement.

Some of those old 9”x9” floor tiles are cracking. Do they contain asbestos? Is her family in danger?

No. They are not in danger.

Many of the materials in the house, from the joint compound used between sheets of drywall, the window glazing, and many types of caulking, to the ironing board cover and the floor tile, contain, or encapsulate, asbestos. For those rare houses with the heating and cooling ducts are embedded in the concrete floor at ground level, the ducts themselves may contain a high level of asbestos.

As long as any of these materials are in sound condition there is little likelihood that they will become friable asbestos, which is to say that they will allow extremely small, lightweight asbestos fibers to become airborne in a house.

But if any of these materials are badly damaged, or worn, or mishandled they are no longer non-friable asbestos. For example, if a floor sander were taken to asbestos asphalt tile flooring, or the asbestos concrete shingles were broken apart into small pieces as part of a renovation, it is quite likely that an entire house, and possibly adjoining houses, could be contaminated with dangerous asbestos particles.

There is no way that I, or any other professional, can do an on-site test for asbestos. I have to send samples to a qualified lab. I once inspected a house with three popcorn ceilings. We took samples from all three ceilings and sent them out for testing. Two had friable asbestos. But one had no asbestos.

For 40 years I’ve been sending samples of suspect materials to the same lab, where they are analyzed using Polarized Light Microscopy. All of these samples have been of materials that fall apart when they are lightly touched, giving rise to a white dust of particles that are about the size of cigarette smoke and can remain airborne and breathable for a considerable period. These are usually samples from insulation on heating pipes or samples from popcorn ceilings, that were popular in high schools and condominiums in the 1970s.These readily disturbed materials are said to contain friable asbestos, easily airborne asbestos, of any of the five quite different types of asbestos that have been prevalent in the United States.

The lab I use tells me that most of the 9×9 floor tiles they test contain less than 3% asbestos, and the tiny bit they do contain is safely embedded in asphalt. Some of the old 9×9 tiles contain no asbestos, while many of the newer 12×12 tiles do contain asbestos.

That’s because the United States has never outlawed asbestos, unlike European countries. As a result, weird things can happen here.

One example: In the 1980s Congress passed a law to protect school children from asbestos exposure. In response, a number of school systems removed all floor tile containing asbestos. And guess what replaced it? They were replaced with new floor tile that also contained asbestos.

In the U.S., asbestos is still used in some automotive brake pads, some brands of caulk and even brand-new buckets of drywall joint compound. You should definitely avoid any joint compound containing asbestos since it needs to be sanded once it has dried – and that could put tiny asbestos fibers into the air.

How can you tell if joint compound is dangerous? If it’s white, it’s unlikely to contain asbestos. But if it’s off-white or beige, the Maryland EPA strongly recommends against using it.

In some older houses, ducting for your air conditioning and heating systems attached to the ceiling is protected from vibrations in the furnace by sections of off-white cloth. That cloth is asbestos cloth; it’s made from asbestos fibers. It should be removed by a licensed contractor and replaced with modern flexible noise dampers.

So how did we get into this asbestos mess? Well, actually, this “mess” has been used by humans for centuries, and its dangers have been known for almost as long.

Asbestos cloth was one of the technological marvels of antiquity. Asbestos fibers, like cotton fibers, are quite tiny but can be spun into longer fibers to make rope and cloth. To launder asbestos cloth, you simply put it in a fire.

In ancient times, Europeans made asbestos cloth and sold it to China, using the trade routes that Marco Polo wrote about 12 centuries later. Pliny the Elder, who died in the volcanic eruption that destroyed Pompeii, wrote about the diseases we now call asbestosis and mesothelioma. He called them a slave’s disease, because it was slaves who spun the asbestos threads into cloth and ended up dying at an earl age.

In the Middle Ages, Charlemagne had one too many festive banquets ruined by tablecloths catching on fire. So, he ordered a banquet tablecloth made of asbestos cloth. Some say he enjoyed throwing it into the fire to prove he could perform magic, because the tablecloth never burned.

In wartime sieges, beautifully engineered weapons would catapult arrows, stones, rancid dead animals, or even incendiary bombs over the walls of castles to create misery among the people within the walls. The incendiary bombs would be made of burning materials such as tar. They were set afire before being launched, but the fire was contained in an open bag of expensive asbestos cloth.

During the Industrial Revolution, asbestos was used on everything from the insulation for steam engines to jackets for firefighters. In 1884, Johns Manville began manufacturing asbestos cloth in large quantities.

By the 1920s a number of cotton mills in the United States converted to manufacturing asbestos cloth. Their profits tripled. But these mills did not provide protections for workers, or benefits for their survivors.

The workers in these mills were some of the country’s earliest fatalities from asbestos.

I have had one friend die of asbestosis. He was a non-smoker, who worked in the shipyards in San Francisco.

As he recalled in one of our conversations, all the shipyard workers envied the pipe laggers. Sure, they worked with asbestos. But most shipyard jobs were even more dangerous, from welding to pouring molten lead.

Many of the materials these workers handled were heavy and cumbersome. A day’s work could easily include cuts, burns, or even broken bones. In contrast, cutting and fitting lightweight asbestos insulation was easy and seemed safe.

My friend told me that in the 1970s a new manager of the union that represented shipyard workers who handled asbestos noticed that the retirement funds were unexpectedly high.

Even in the 1970s there was little protection from asbestos dust. New union members would join right out of high school, delighted to have a good job. As my friend recalled, they would all smoke cigarettes on break, and, not surprisingly, few of them ever made it to retirement age.

Most people who suffer from asbestosis have worked around asbestos dust for many years or even decades. It normally takes about 30 years for asbestosis to be fatal.

In the early 1970s, the British Parliament passed a practical but cynical law intended to benefit older unemployed men who had dropped out of school at a time when British law allowed children to stop their schooling at age 13.

As they grew older, they had few other job prospects, so the law specified that all asbestos workers had to be age 50 or older.

Many other workers have spent their working lives around asbestos dust. One example would be workers in highway tolls booths. Why? Because until recently, asbestos was a major ingredient in the brake pads of cars. Yet according to the branch of the Maryland EPA that deals with asbestos issues, there are no known Maryland toll collectors who have come down with asbestosis.

Likewise, auto mechanics who routinely work around asbestos dust in repairing car breaks, are not known to suffer from asbestosis. There has been speculation that movie star Steve McQueen, who died of mesothelioma, a lung disease caused by asbestos, was exposed to asbestos dust from working on cars and car breaks.

But it is also possible that he was a fan of Kent cigarettes with the “Micronite” filter. These filters used crocidolite asbestos to protect smokers from tar and nicotine. Crocidolite asbestos is one of the most toxic types of asbestos.

The process of removing friable asbestos is expensive – ranging up to $30,000 for some houses that have asbestos pipe lagging on the heating pipes of their basements. This is largely because insurance companies don’t want to insure people who work with friable asbestos. So, while the worker in the hazmat suit might be making $20 an hour, their company,which has a special license to abate friable asbestos, could be paying as much as $500 for each hour a worker is exposed.

Another area of concern is the ductwork under a concrete slab on grade. These ducts are either metal or transite, a type of concrete tube which usually has a high degree of asbestos. On the rare occasions when we inspects a building with transite ducts that seem to be working properly, we recommend that some type of epoxy or thick glue be put along the exposed edges of the transite as it comes up through the floor, right below the removable metal supply register.

Unfortunately, in many cases transite ducts suffer from seepage and breakage. As they take on water they may continue to shift and crumble. As they dry out there is often a strong smell of mold. In short there are now two health hazards, mold spores and asbestos fibers. In buildings like this we usually recommend installing a new distribution system.

But what about those basement tiles? The State of Maryland allows anybody to remove or handle floor tiles or shingles that may contain asbestos – provided they are removed carefully and not broken-up or pulverized. Taking them out with a grinder or other abrasive tools will require a permit, as well as an inspection by local authorities and possibly even the Maryland EPA.

Pulverizing concrete asbestos shingles, or using a floor sander on floor tiles can easily turn non-friable asbestos into friable asbestos that can easily contaminate an entire house, if not neighboring houses as well.

For asbestos shingles, the recommended removal procedure is to start at the top, prying the nails loose without destroying the shingles.

For floor tiles, safe removal calls for a heat gun and a scraper. This will often leave lumps of asphalt-based adhesive on a floor. These adhesives tend to loosen up when they are coated with the hand cleaner used by auto mechanics, available in automotive parts stores. The adhesive can then be wiped up or flattened with old newspapers or paper towels.

Personally, I think it’s a lot easier to simply cover over old floor tile that is in poor condition. Start by removing the loose pieces and leveling the empty spots. Then it’s relatively easy and inexpensive to install new vinyl tiles that have a self-adhesive bottom side protected by a tear-off plastic film.

Before installing, I suggest you paint the old tiles with a primer, which will help the new vinyl tile to adhere more securely. I did this about 20 years ago in a bathroom of our 100-year-old house, and those cheap tiles are still in sound condition.

In Maryland, materials containing nonfriable asbestos do not have to go to an approved federal EPA dump. Many counties in Maryland have landfills that will accept these materials. They should be double bagged in trash bags with the outside bag labeled: “Material that may contain nonfriable asbestos.”

If you suspect that you have friable asbestos, you should have a sample taken by a trained professional.

I have used AMA Analytical Services, Inc. in Lanham, Maryland for more than 40 years If you want to analyze a piece of floor tile, please contact them for advice: (amalab.com; 800-346-0961). Their fees are reasonable, and their customer service is outstanding.

In short, friable asbestos is clearly a danger for any family. But asbestos floor tile and asbestos shingles are not, provided they are in reasonably good condition. If they, or any housewares that may contain asbestos, are damaged or crumbling, you should repair or replace them. But you don’t need a specially licensed asbestos contractor to do so.

Jack Reilly has lectured to over 600 home inspectors and private building inspectors on the problems and dangers of residential lead paint and asbestos. In approximately 1981 he published the first national magazine article, in The Old House Journal, on the uses and dangers of residential asbestos. He can be reached at JackReillyAssociates.com or 301-351-5040.