A few years back, I wrote about a house contaminated by toxic mold.

The house was so badly contaminated that the homeowner had to borrow from relatives just about what it cost to buy the place originally so he could pay the cleanup costs.

We are talking about $300,000-plus. When the cleanup was finished, the house was mold-free. The causes of contamination -- water intrusion and poor construction practices -- also had been identified and corrected.

The job took a year. By then, the homeowner was so in debt that he had to sell the house, and at a loss. His homeowner's insurance covered practically nothing.

He lived in a state that required seller disclosure, and few buyers were willing to touch that house, despite all the guarantees that would be appended to the sales agreement.

Fast forward past Sept. 11, 2001. In the months that followed, deadly anthrax was discovered in many government and private facilities along the East Coast, including the Capitol Building in Washington.

The potential for widespread death was terrifying. John Mason, whose company was responsible for decontaminating all of the affected buildings, said that the amount of anthrax contained in just four sugar packets represented 100 million lethal doses.

Sabre Technical Services, which is a subsidiary of Mason's company, Bio-One Solutions of Albany, N.Y., rid these buildings of anthrax by fumigating them with a patented treatment that uses chlorine-dioxide gas. This is the same chlorine dioxide that is used in food, water treatment, oil production and destruction of medical waste.

"The process sterilized the Capitol Building well beyond the requirements of a hospital operating theater," Mason said. One of the anthrax cleanup sites in 2001 was the 17-acre Brentwood postal facility in Washington, D.C. The Brentwood cleanup took 18 months and cost $180 million.

"Thanks to advances we've made in software technology and procedures in the last four years, we could do it in days and for much less," Mason said. Today, the Brentwood decontamination would take 30 days and only cost $25 million.

Although the jury is still out on the health effects of household mold, the same chlorine-gas fumigation process that Bio-One uses on anthrax and other biohazards appears to work well on mold.

"John is attempting to scale down the technology to residential applications," said Rudolph Giuliani, the former New York mayor and chairman of Giuliani Partners LLC, which is part of the Bio-One joint venture.

Late last year, Sabre used its decontamination procedures on a three-story, mold-contaminated building in Utica, N.Y. The thousands of surface samples taken in Utica building after decontamination found no evidence of mold growth. This included underneath wallpaper, under heavy layers of dirt and biological material and in interior wall cavities.

Airborne samples taken after treatment showed no difference between levels outside the building and inside it. The results were verified by independent testing.

"Our chief concerns are ensuring that the building is completely free of residual toxicity and allergens," he said. "Chlorine-dioxide fumigation rids the building of mold contamination, but it doesn't guarantee that mold will not begin forming again. That only can happen if the source of mold, moisture intrusion, is eliminated completely."

One June 8, Sabre began a critical test of its mold fumigation procedures at a former Ames Department Store building in Kingsbury, N.Y., about an hour's drive from Albany.

The building is pervasively contaminated by mold. Sabre will use it to try to reduce its decontamination procedure to six days, which would be the fastest time to date for a medium-size structure.

The increased speed is the result of several things, including improved technology in how and where the chlorine dioxide gas is emitted into the building, covering the building with a negative-pressure tent, and quicker sampling and testing processes.

The process of fitting a process used to tackling biohazards in large public buildings won't happen overnight, but Mason and Giuliani are confident that it will happen.

There are, of course, other issues involved in residential mold contaminations, and one of the most important is litigation. Many homeowners insurance companies have restricted or eliminated coverage of household mold contamination and cleanup from their standard policies after a series of lawsuits in Texas and California resulted in large awards to homeowners.

Although Bio-One is focusing its attention on mold, Mason has by no means forgotten the events of the fall of 2001 and the fact that bio-terrorism remains a threat.

"It's not so much a question of the likelihood of another attack, but where," Mason said.