Asbestos removal is a complicated and expensive procedure that many school officials are not familiar with, yet an improperly conducted job can exacerbate the health risks they are attempting to abate, according to contractors, medical experts, and consultants involved in asbestos work.
What follows is a summary description of a typical asbestos-removal job as conducted by Anthony Natale, a New Jersey contractor whose work is cited by experts and government officials as representative of the best available asbestos-abatement techniques. (The summary does not describe the process step by step but illustrates some of the technical considerations that underlie a careful asbestos-removal job.)
Apply to Encapsulation
Many of the precautions taken are also applicable to less expensive abatement procedures, such as encapsulation or enclosure, which disturb the asbestos-containing material and enhance its chances for releasing dangerous fibers.
During encapsulation, the asbestos-containing material is coated with a bonding agent, called a sealant. During enclosure, the asbestos material is separated from the building environment by barriers such as suspended ceilings. These measures are designed to prevent the material from releasing fibers into the environment.
The Environmental Protection Agency recognizes in its guidance documents, however, that removal is the only permanent solution. Experts warn that the weight of the sealant, and the water vapor that builds up behind it, can weaken the “integrity” of the asbestos material and cause it to crumble.
The experts further warn thatn enclosure is damaged or entered for maintenance, the fibers that have collected in the enclosure will escape into the building environment.
According to Mr. Natale, the average cost of asbestos removal is $6 a square foot, but that figure can vary greatly depending upon a number of factors, including the location of the material and how soft or hard it is.
Mr. Natale, the president of Duall Corporation of Mount Laurel, N.J., is co-author of the book Asbestos Removal and Control, An Insider’s Guide to the Business, with Hoag Levins, a former staff writer for the Philadephia Daily News and the Philadelphia Inquirer.
Air Engineering
After a comprehensive set of pre-tests to determine the level of contamination in a building, workers enter the school to set up an air-control system.
“You have a decontamination area and workers are going to move through that area,” Mr. Natale explains. “So you want to create a negative pressure in your work area so that all air moves to that work area.’'
To do that, workers install a Micro-Trap, or “negative air unit,” which has three filters to trap gross and submicron asbestos particles. One is a “high-efficiency particulate absolute” (hepa) filter similar to that used in the nuclear industry.
The system forces clean air in continuously from one main opening and prevents contaminated air from escaping through rips or tears in the plastic-enclosed decontamination area.
Air is released from the building after it has been filtered through the machine, which is capable of moving 25,000 cubic feet of air every 15 minutes. An important feature of the machine, Mr. Natale says, is that it sounds a warning when it shutsor mechanical reasons.
The process is complicated in a building that has areas of “dead space” where air does not readily circulate. “If you have a dead area,’' Mr. Natale says, “you may want to put a flap in the plastic there, or a valve, to let air come in that area to flush that area toward the filter.”
The process, Mr. Levins adds, “is air engineering.”
Sealing In Plastic
Once the “negative-air-filtration system” is in place, workers enter the area armed with rolls of polyethylene plastic, duct tape, staple guns, razor cutters, and spray adhesive.
They then proceed to enclose the contaminated area in an air-tight and water-tight capsule of plastic.
Generally, two layers of 6-milc--which is about twice the thickness of plastic garbage bags used in the home--are laid on the floor.
Four-mil plastic is then taped to the top of the wall so that only the asbestos surface of the ceiling is exposed. The worker should be careful, Mr. Natale says, not to rub his fingers or knuckles across the ceiling because such movement can release asbestos fibers.
The bottom of the plastic is taped over the floor-lined plastic, which is taped about a foot up the wall.
“You cover every window, you cover every door, you cover every ventilator,” Mr. Levins notes. “You cover every place that air moves in and out of the building.”
In reality, however, sealing an area in plastic “is the most insignificant part of the job,” according to Mr. Natale. “If you have a wall that’s been exposed to asbestos, you don’t want to add to that contamination because your final cleanup will be that much more laborious. So you protect the walls from the splashing, the mud, and the slop that’s going to fly around in there.”
Disposable Clothing
During removal, workers dress only in disposable white coveralls, briefs, and hoods to protect them against chunks of asbestos-containing materials. “It doesn’t protect them against asbestos fibers,” Mr. Natale notes. “These are paper clothes. The fibers go right through the cloth. They raise their arm, it rips underneath; they spread their legs, it rips open. They bend, the back rips out. In reality, all this is is a modesty.”
Upon leaving the decontamination area, the workers enter the first of three rooms located in what is called an “airlock.” There, they undress, leaving their respirators and hoods on.
Proper Respirators
Paper masks and dust respirators, which commonly sell for as little as 60 cents, “are absolutely useless and provide no protection,” asserts Mr. Natale.
He says he provides $13 half-face masks that, properly fitted, offer adequate protection for jobs requiring minimal protection. The masks, he explains, provide an airtight seal over the worker’s face. Inhaled air comes in through two cartridge filters and exhaled air escapes through a bottom exhaust valve. Four times a day the cartridges, at $2.40 each, are replaced, Mr. Natale says.
For removal work that requires heavy exposure, Mr. Natale uses “supplied-air” respirators that cost around $500 each. The worker, he says, wears a powered fan on his hip that draws air through three hepa filters and forces it to the face.
That way, Mr. Natale explains, “even when the guy draws in air, the pressure in his mask is greater than the outside environment so he doesn’t draw in asbestos fibers.”
After the workers undress in the first room of the “airlock,” they enter a second room in which there is a shower. There they wash themselves and their respirators.
In the third room, the men put on “clean whites.” They then move into a locker area, some distance away, where they put on their street clothes.
The process is repeated four times a day--each time the workers take a break. The disposable clothes are not reusable.
Wetting Down
Before the actual removal takes place, the asbestos-containing material must be soaked. To make the water “wetter,” workers apply a “surfactant"--a chemical that reduces the surface tension of water so it can penetrate the asbestos-containing material more easily.
“The wetting [process] is the most dangerous. It releases the most fibers,” according to Mr. Natale.
“The more you wet, the better,” he adds, “but there is a line you have to draw because of the structural damage you can cause by too much water.”
The next step is to scrape and then wire-brush the surface that has been stripped. Then the surface is rinsed.
“The mechanical process is just arms and legs,” Mr. Natale says. “There’s nothing scientific about it. It’s just manual labor.”
The Cleanup Begins
The chunks of asbestos that are scraped from the ceiling land on the floor, where they absorb the water that fell during the wetting and rinsing processes. When the scraping is completed, the cleanup begins.
With shovels, the workers heave the asbestos waste into bright yellow bags that are labled with “Caution-Asbestos” warnings. When full, the bags are twisted and sealed with duct tape. Material that has the potential for ripping through the bags is placed in drums.
When a substantial number of bags or drums are filled, they are passed into a special waste airlock where they are placed in a clean yellow bag. Workers then pass the bags outside the building where they are placed in a closed truck or toxic-waste dumpster.
Back inside the decontamination area, workers spray the polyethylene plastic with a mist of water to prevent a rapid rise in the airborne-fiber count.
Then, the plastic is removed.
In some cases, a bonding agent, such as latex paint, will be sprayed onto the stripped ceiling to seal any invisible fibers that may remain in the porous surface. In these cases, one layer of plastic is removed before the sealant is applied. Once that process is completed, the rest of the plastic is removed.
Wet Wipe and Vacuum
After the plastic coverings have been removed, they are treated like asbestos waste and placed in bright yellow bags for disposal. The negative-air-filtration system is still running. Also running is a laser-light-operated monitor designed to show whether the level of asbestos fibers is increasing or decreasing. The machine runs throughout the removal job.
Meanwhile, workers, who wear personal air monitors throughout the removal job, wet-wipe all surfaces with paper towels. A new towel is used for each four-foot-square area. A hepa vacuum cleaner is used in areas that are hard to reach.
Each room, Mr. Natale says, is cleaned--toward the filter--about two or three times, or until the laser-light monitor indicates that the area is clean.
First, however, a visual inspection is conducted to ensure that there are no visible signs of dust.
Dust samples and air samples are also taken and analyzed to ensure that the air is free of invisible asbestos fibers.
When the air samples are taken, Mr. Natale notes, it is important “to sweep a broom or flap plastic.” That, he explains, creates an “artificial activity” that approximately simulates the air movements that occur when teachers and students occupy any classroom.
“Most people think the whole process [of asbestos removal] involves ripping out tons of asbestos,” Mr. Levins says. “In reality, the real job begins after you rip out the tons of asbestos and you have to clean the air of the invisible fibers that pose a threat of cancer.”
