You may remember the environmental scare over chlorofluorocarbons (CFCs) three decades ago. They were destroying the ozone layer in the earth’s atmosphere, we were told. They had to be banned.

And so they were, through international agreements beginning in 1987. CFCs were taken out of refrigerants, aerosol cans, solvents and certain foam products. Some of what we buy today is more expensive because of the change.

Well, problem solved, at least.

No. Problem not solved.

Despite the scare and expensive action taken worldwide to address it, emissions of the second most-common type of CFC are rising, scientists say. The chemical is called CFC11.

Scientists have no explanation.

“It’s the most surprising and unexpected observation I’ve made in my 27 years” of measuring such emissions, admitted Stephen Montzka of the National Oceanic and Atmospheric Administration.

Montzka was the lead author of a study revealing the increase in CFC11 emissions.

If humankind has virtually banned production of CFCs and their use — as it has — where are the emissions coming from?

Some are emitted from structures that used CFCs long ago. But that amount is far below what is being detected, scientists report.

One, Ross Salawitch of the University of Maryland, maintains the higher emissions are because of “rogue production” of CFCs.

If so, producers ought to be identified and shut down with no further delay.