In the first case of its kind, a San Diego man was caught allegedly smuggling greenhouse gases from Mexico into the United States and then selling them for a profit.

Federal prosecutors say Michael Hart was arrested on Monday on a criminal complaint that he violated regulations intended to curb the use of greenhouse gases and slow climate change.

A 2020 law prohibits the importation of hydrofluorocarbons (HFCs), commonly used as refrigerants, without allowances issued by the Environmental Protection Agency (EPA).

The indictment alleges that Hart purchased refrigerants in Mexico and smuggled them into the U.S. in his vehicle, concealed under a tarp and tools.

Hart then allegedly posted the refrigerants for sale on OfferUp, Facebook Marketplace and other sites, and sold them.

"The illegal smuggling of hydrofluorocarbons, a highly potent greenhouse gas, undermines international efforts to combat climate change," said David M. Uhlmann, EPA Assistant Administrator for the Office of Enforcement and Compliance Assurance.

"Anyone who seeks to profit from illegal actions that worsen climate change must be held accountable."

Hart pleaded not guilty at an arraignment on Monday.  He was due back in court on March 25.

According to the EPA, HFCs are potent greenhouse gases that cause climate change and are used in applications such as refrigeration, air-conditioning, building insulation, fire extinguishing systems, and aerosols.

The global warming potential of an HFC can be hundreds to thousands of times more potent than carbon dioxide.

The U.S. government says the use of HFCs has been rapidly increasing worldwide due to the global phaseout of ozone-depleting substances and increased demand for refrigeration and air conditioning.