Asbestos officially was declared a lethal substance by U.S. government agencies and the World Health Organization 25 years ago, and entities all over the country have been engaged in abatement activities ever since — except in the tunnels beneath our own Capitol complex.

What’s gone on there is a horrific scandal that is only now coming fully to light — the persistent exposure of tunnel workers to flaking asbestos and the failure of the Architect of the Capitol to take corrective measures despite at least seven years of warnings.

Under the best of circumstances, the working environment for the 10-member Capitol “tunnel shop” team resembles that of hell. The temperature runs to 140 degrees. The five miles of tunnels running heating and cooling pipes and various utility cables from the Capitol Power Plant to the Capitol and 23 Congressional buildings are narrow and dark, and the work — welding, steam-fitting, insulation and electrical repair — is demanding and hazardous.

And the tunnels and pipes are lined with asbestos that’s easily knocked loose, exposing the workers to airborne contamination levels 30 times government-approved levels. Asbestos also rises out of various tunnel vents around the Capitol area, endangering the general public.

According to a formal complaint filed by Congress’ Office of Compliance last year, the problems of asbestos, falling concrete and lack of adequate exits from the tunnels were first brought to the attention of the AOC as early as 1999 and repeated warnings have been issued ever since.

The record indicates that, while former Architect Alan Hantman repeatedly assured Congressional committees that the situation was being dealt with, a Government Accountability Office report late last year found that “limited work has been completed and the workers have no clear picture when the work will be done.”

The chief of the tunnel crew, John Thayer, recently testified that his men were equipped with respirators only last year, that contractors hired to clean out the tunnels have done inadequate work — and that complaints by tunnel workers have been met with threats of retaliation by officials in the Architect’s office.

Members of Congress are now speaking out in the outraged terms that the situation calls for. Rep. Ray LaHood (R-Ill.), a member of the House Appropriations subcommittee on the legislative branch, declared the AOC’s actions “inhumane” and “unprofessional” and said that tunnel workers “are probably going to end up dying” because of their exposure. “Someone has to be held accountable,” he said, and demanded that Hantman appear before the subcommittee. The new chairwoman, Rep. Debbie Wasserman Schultz (D-Fla.), declared the situation “unconscionable” and promised that Hantman would be subpoenaed, if necessary.

What’s more important is that the tunnels be fixed. It is going to cost money — lots of it. There is $50 million in the current Iraq supplemental appropriations bill for the task. Wasserman Schultz has mentioned $125 million as an appropriate figure. Thayer said it would be $500 million — rivaling the cost of the Capitol Visitor Center — and take 15 years to complete. Whatever it takes, it’s got to be done.