VATIS UPDATE Article

A new study done by scientist Lei Hu at Cooperative Institute for Research in Environmental Sciences (CIRES), the United States, and scientist Stephen Montzka, at National Oceanic and Atmospheric Administration (NOAA), the United States, has reported those rates are still 30 to 100 times higher than amounts reported to Carbon tetrachloride (CCl4) emission inventories. The study also suggested 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 like Teflon and Polyvinyl chloride (PVC)].

Despite that phase-out, the decline of CCl4 in the atmosphere has been unexpectedly slow. To investigate the U.S. contribution, Montzka, Hu and colleagues from NOAA, CIRES, and other scientific institutions studied observations made from NOAA’s North American air sampling network. Since the late 2000s, they tracked the composition of the atmosphere from this network of 9 towers and many more regular aircraft-sampling sites across North America. “We wanted to identify where these emissions were coming from, as well as their magnitude,” Hu said.

The team looked at high-density population areas to determine if the use of bleach or chemicals in laundry or swimming pools might be responsible for the emissions. They also checked into industrial sources and here they had some help. “We can’t tell exactly what the sources of emissions are. It could be underreporting from known sources, it could be an unknown source or both. It could be some other activity that’s geographically tied to the production of chlorinated chemicals and products that hasn’t been recognized previously,” said Montzka.