The light of a bare bulb glared upon the tiny scratches in my respirator lens, and illuminated the dark misty crawl space, now cold on this 70-degree day. I direct the spray of frozen CO2 pellets, onto the stained joists and sub floor, lying on my back only two feet below my target. I watch the fog of dry ice, as it blasts from the nozzle, impacting the wood a few inches away, before magically disappearing into thin air.

Or so it would seem...

My partner, Chris, taps my shoulder and signals to stop. With the respirator, the earplugs and the hood of my Tyvek suit, it is useless to yell over the loud hiss of high-pressure air that impels the tiny dry-ice pellets to crash onto the target, literally vaporizing them upon impact. The oxygen meter strapped to my wrist begins to vibrate, pulsing to the red flashing LEDs, and the morning alarm-style squeal. Moments later, my lungs confirm the alarms, as each breath becomes less effective than the last.

Chris points to the negative-air unit used to exhaust the C02 gas. He lifts the electrical cord, then pulls an open hand across his throat and points up. A circuit has blown, and the exhaust fan is off. We wait a few moments to catch our breath while the backup fans clear the suffocating gas. Within a few seconds, my oxygen-sensing watch reads 21.0 percent, the normal amount of oxygen in outside air. Within a few minutes, we're back on-line, and I continue my pattern, making sure to start exactly where I left off.

The safety controls have worked and avoided potential disaster. I make a mental note to always require a dedicated circuit for the exhaust fans while my partner repositions it into the capture zone of the next section to cryo-blast.

I begin again, but no ice emerges. For a few minutes, we wait motionless, semi-relaxed, the hissing air drowning out our thoughts. The supply line might be frozen with C02, and I consider ways to clear the blockage.

The blasting machine might be out of ice, and I picture Charles reaching into the container - where the atmosphere reaches as low as 4 percent oxygen - half-filling the five-gallon bucket and rushing it to the blasting machine. Once there, he pours it in slowly, making sure it's a uniform consistency, free all chunks. It's a few hours into the second day, and we're reaching the last of the first container. The ice has been exposed to the atmosphere the entire day before, and it's degraded and chunky.

Outside, two team members disconnect the ice-hose at the outlet of the blasting machine-where the diameter of the supply line is reduced-and clear the chunk of ice from the path. We continue cryo-cleaning intermittently, with continual delays, until the first container is empty.

After lunch, we open the new container, and the fresh ice enables us to cover a lot of ground, quickly and effectively. We continue smoothly until a few hours into the following day, the degraded ice begins to clog, and I summon my patience once again.

Patience is just one of many virtues and talents necessary when experimenting with a new technology, defining a new field. In any field-testing environment, one must expect unseen obstacles, and welcome the challenge of finding immediate solutions, while the crew awaits direction. Successful completion of the job hangs on every decision.

As the owner of SteamMaster, Gary Gilman knows this stress well. For 25 years, he has been on the forefront of technological cleaning solutions. Starting with carpets, he quickly expanded into water and fire damage restoration, auto detailing, upholstery, hard surface cleaning and soda-blasting.

His latest interest is cryo-blasting, and he might have found a niche in mold remediation. Years of remediation experience has shown him that mold is most commonly found in attics and crawlspace, where it is the most difficult to safely remove. Until recently, Gary followed the standard procedure of sanding and wire-brushing the affected areas in order to remove the staining and hyphae - the roots of mold that become embedded in the wood framing.

Gary pays attention to fine detail, and he's known as a hard man to please. The drawbacks of sanding left him completely unsatisfied. There are many places a handheld sander cannot reach; especially considering a mold spore can go anywhere air can go. It's tiring, slow work that at best produces a less-than-thorough job.

Sand or soda blasting would be ideal to remove mold from tight corners and behind pipes, wires and nails present in crawls and attics - except for the medium. The mess, poor visibility, and cleanup make it out of the question for mold remediation. Too bad the blast medium doesn't just disappear upon impact!

This is where Gary sees a unique opportunity.

Background
The call came in at 10:35. It was a typical flood involving a typical crawlspace. When mold was discovered in a closet and on the floor joists, further investigation revealed growth on the studs of two bathroom walls. Following proper procedure, the insurance adjuster called an independent industrial hygienist, whose investigations revealed elevated levels of spores.

SteamMaster representatives met the IH to inspect the job firsthand. The IH agreed that cryo-blasting was a feasible option. He included the procedure as a possible method of remediation, and Gary was prepared-or he would be, if I could find a way to load the 2,000 pounds of frozen C02 pellets into the van.

The back of the van was a foot lower than the dock, and the warehouse manager refused
to load it. Fortunately, a veteran forklift driver saved the day. After close inspection, he confidently mounted the forklift, and slowly, carefully, loaded the first 1,000-pound container. His next question did not diminish my elation. The one-ton chassis would carry the heavy load, and the V-10 engine would hardly hesitate over the continental divide separating Denver and Vail, Colo.

When blasting with dry-ice, time is of the essence. Accurate scheduling and estimating are critical. As critical as a smooth execution of the plan, which becomes more complicated with the fact that there is no C02 pelletizer in the greater Denver area. The ice must be ordered at least 24 hours in advance. Procurement arrangements require the frozen CO2 pellets to be shipped from Wyoming to the warehouse in Denver, where we then pick it up for transport to the job site.

Frozen CO2 is very volatile, and in our atmosphere, turns from ice directly into vapor, skipping its liquid phase as it warms. To maintain the ice as long as possible, it is stored in large insulated containers. The container is first double-lined with polyurethane, then sealed at the top, and the airtight lid is locked into place. Finally, the lid is sealed onto the container with a cellophane plastic wrap.

Watching the van sink under the weight of the first four-by-four-by-four plastic box container, a ton of frozen C02 seemed like a lot. Even in these unmanageably large, tightly sealed containers, the ice does not last more than three days after opening.

I wondered if we'd finish the job before the dry ice became unusable, and I ran through the estimate again.

The area to clean measured just over 1,100 square feet of flat floor space, not including joists. An airless sprayer covers a square foot of sub floor plus joists in about 30 seconds. This brought us to estimate 10 hours of blast time, i.e., the time that ice is emitted from the nozzle.

After moving equipment and hoses, contorting our bodies in the tight crawlspace, establishing smooth ice-flow, and adjusting the negative-air machine to maintain a close capture-zone, blast time equaled about one-third of the total time to complete the job.

When the flow-rate on the Cold Jet™ Blaster was set to three pounds per minute, sufficient coverage took longer than we estimated. At four pounds per minute, however, we covered a lot more area, much more thoroughly. Even though the ice was used more quickly, the increased production rate and quality made the job much more efficient.

In the infantile, undefined mold industry, however, even the smoothest most efficient job might incur unwanted costs.

We followed the U.S. Environmental Protection Agency and New York City guidelines by the book. We took extra steps to course a thorough job. We remediated the mold, coated all affected areas with clear anti-microbial sealant and created a dust-free environment, all the while scrubbing the air and maintaining strong negative pressure.

We even used Fiberlock IAQ 6100 as the antimicrobial sealant, which is white when it's applied, but dries in to a clear finish. This allows the industrial hygienist to inspect the areas after sealing. When the sealant dries white, the remediation contractor can apply it directly over existing mold and charge for remediation work he did not do.

Perhaps we failed clearance in the smallest closet because we removed only the bottom four feet of sheetrock. Or perhaps we failed because of the ratings-driven fear, spread throughout a public audience that is uninformed about the realistic dangers of mold.

Whatever the underlying cause, a single Stachybotrys spore was detected in the closet air sample, gathered with an Anderson N-6 Bio-aerosol sampler, and Zefon brand Air-O-Cell sample. One spore found in the 0.15 cubic-meter of sampled air, mathematically equates to seven spores per cubic meter.

As with many air quality companies, the one responsible for our clearance testing has adopted a 'zero-tolerance' rule toward Stachybotrys. As a result, the hygienist required SteamMaster to clean this area again and pay for the retesting, conducted by the same hygienist.

On the day we found out about our single-Stachv-spore failure, we met with the president of a different industrial hygiene company to discuss a different job. When our failure came up in conversation, he quickly produced his own clearance criteria for mold remediation post-tests.

Imagine the mixture of liberation and frustration we felt when we read following: "In addition, a healthy indoor environment should not yield air sample results that contain known toxigenic or pathogenic microbial organism in a concentration greater than 21 spores per cubic meter."

With these clearance criteria, the first clearance test could have revealed three times the amount of Stachybotrys and still passed.

Stachybotrys is sometimes dangerous, especially to infants, the elderly and those with depressed immune systems, but it is not always dangerous to everyone. The media have exploited a few incidents, inciting fear within an uninformed public and clouding common sense. Many people in the medical community hold that opinion that Stachybotrys is no more dangerous than other known toxigenic molds.

The industrial hygiene firm that specified cryo-cleaning in the scope of work was extremely impressed with both the digital photos documenting the progress and with the final visual inspection. They intend to specify this procedure on future remediation jobs, as the need arises.

Safety
In addition to full mold personal protective equipment the following safety precautions are necessary when working with frozen C02:

• Wear insulated leather gloves, because C02 is -98 degrees Fahrenheit. Skin will freeze with prolonged contact.
• When scooping the ice, never put your head inside the container.
• Always blast with a partner. Decide upon clear, simple sign language to use, and always use a low-oxygen alarm.
• Plan ventilation. Cross-ventilate when possible, and make sure there is sufficient air movement to remove the C02 before it builds up. Use an O2 alarm and never work alone.

Quentin Danziger is the manager of the restoration division of SteamMaster Cleaning and Restoration in Vail, Colo. He is a site supervisor and certified mold remediator with a bachelor’s degree in engineering physics from Colorado School of Mines.

Gary Gilman is the owner of SteamMaster. He is a project manager and certified mold remediator. He has been remediating mold in the Vail Valley, Colo., for 20 years.

They can be reached by e-mail at gary@steammaster.com or by phone at (800) 527-1253.