Despite Ban, Ozone-Eating Chemical Remains Prevalent

by | Mar 14, 2016

Scientists used observations from NOAA's North American air-sampling network to track surprisingly high levels of carbon tetrachloride (CCl4), a banned chemical known to deplete the ozone layer (pictured). (Credit: NASA)

Scientists used observations from NOAA's North American air-sampling network to track surprisingly high levels of carbon tetrachloride (CCl4), a banned chemical known to deplete the ozone layer (pictured). (Credit: NASA)

Carbon tetrachloride (CCl4), once commonly used as a cleaning agent, is a known air toxin that eats away at the ozone layer. Its production has been banned for many years, but a new CIRES and NOAA study reports those rates are still 30-100 times higher than amounts reported to emission inventories.

We've been scratching our heads, trying to understand why, said NOAA scientist Stephen Montzka. When we look at the amounts produced and destroyed, we would expect the chemical's global concentration to be decreasing at a rate of nearly 4 percent per year. But it's only decreasing at 1 percent per year. So what's happening?

The study suggests that the source of the unexpected emissions in the U.S. appears associated with the production of chlorinated chemicals (such as those ultimately used to create things such as Teflon and PVC). The new analysis was published in the Proceedings of the National Academy of Sciences.

 

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