Federal agents went undercover to catch a man who's accused of using Craigslist to commit a crime against the ozone layer.

Doug Mertz of suburban Detroit is charged with offering to sell R-22 refrigerant on the popular Web site. The Environmental Protection Agency says it's illegal to sell the refrigerant to people who aren't certified to handle it.

Mertz says he was arrested Thursday in Oak Park after selling 10 cans of R-22 for $2,400. It's mostly used in air conditioners and other cooling systems. The government says handlers need a license because R-22 leaks can deplete the ozone layer.

Mertz claims he was entrapped. He says he was just trying to make money in hard times.