If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Greenhouse Gases

Rising chloroform emissions traced to China

A surprising increase in the ozone-depleting gas is likely tied to industry in the country

by Tien Nguyen
January 10, 2019 | A version of this story appeared in Volume 97, Issue 2


An international team of researchers has reported a surprising rise in global levels of atmospheric chloroform. The study in Nature Geoscience posits that the ozone-depleting substance is coming from eastern China (2018, DOI: 10.1038/s41561-018-0278-2).


The rate of increase per year in global chloroform emissions from 2010 to 2015

Atmospheric chloroform can come from both natural sources, such as marine algae, and anthropogenic sources, which mainly include chlorodifluoromethane production and water chlorination. The team found that from 2010 to 2015, global chloroform levels rose at a rate of 3.5% each year, despite being relatively stable or declining in previous decades. They calculated that the increase in emissions detected at measurement stations in South Korea and Japan was similar in magnitude to the global emissions increase and, using models of wind patterns, traced the emissions’ origins back to eastern China, which is highly industrialized. Recently, researchers discovered rogue emissions from east Asia of the banned substance trichlorofluoromethane that may delay ozone recovery by a decade. The spike in chloroform emissions could also delay the ozone layer’s recovery by several months or even years if the rate of increase continues.

With an atmospheric lifetime of less than six months, chloroform is considered a very short-lived substance (VSLS) and is not regulated by the 1987 Montreal Protocol, the successful global agreement to reduce the emission of ozone-destroying gases. Susann Tegtmeier of the Helmholtz Center for Ocean Research writes in an accompanying review that the findings are “an important step toward opening the discussion of regulating the anthropogenic VSLS emissions.”


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.