The Pension Benefit Guarantee Corporation sounded a louder alarm Tuesday in its continuous warnings on multiemployer pension plans.

In its latest Retirement Matters report, the agency said plans covering 1.5 million people are in danger of failing in the next 10 to 20 years.

If they do, the regulator cautions this could put the entire 10 million workers in multiemployer plans at risk, driving the entire federal pension guarantee system into insolvency by 2033.

Multiemployer pension plans were created to help employees in union-based industries who often work for several employers in a year in such fields as trucking and hospitality.

“The math just doesn’t add up any more,” the PBGC said.

The agency said the crisis was fueled by massive plan losses during the recession that have not been fully recouped in the recovery.

Some plans have tried -- and failed -- to insure their futures by increasing contributions and reducing benefits to retirees.