Certain chemicals called chloroflorocarbons, or CFCs that are known to deplete the ozone layer of our planet’s atmosphere were banned by the Montreal Protocol back in 1987. But according to a recent study by NASA, there are high levels of the carbon tetrachloride chemical, or CC14 still accumulating in the atmosphere.

Certain chemicals called chlorofluorocarbons, or CFCs that are known to deplete the ozone layer of our planet’s atmosphere were banned by the Montreal Protocol back in 1987.

But according to a recent study by NASA, there are high levels of the carbon tetrachloride chemical, or CC14 still accumulating in the atmosphere.

CC14 used to be a common ingredient in fire extinguishers and dry cleaning before it was banned along with other CFCs under the Montreal Protocol.

Qing Liang, lead author of the study from NASA is quoted as saying: “We are not supposed to be seeing this at all. It is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites, or unknown CCl4 sources."

The results of the study show that there are still an estimated 39 kilotons of CC14 making its way into the atmosphere every year, which is about 30 percent of the amount seen during peak emissions before the chemicals were banned.

That’s only a decrease of around one percent per year, which is a much slower decrease than experts had predicted at four percent every year.

Data from the study also shows that CC14 actually stays in the atmosphere 40 percent longer than previously estimated.