Wolfson Atmospheric
Chemistry Laboratories

Innovation Way
University of York
York, YO10 5DD

General Enquiries

Jenny Hudson-Bell
01904 322609

Stratospheric ozone protects humankind and our crops from harmful ultraviolet radiation, allowing only a small amount to reach the surface.

Halogens released from long-lived anthropogenic compounds such as chlorofluorocarbons (CFCs), CCl4are the main cause of the depletion of the ozone layer. The ozone hole, which began in the 1980s was a huge worry for the atmospheric community.

The Montreal Protocol and amendments have been hugely successful in limiting the quantity of anthropogenic stratospheric-ozone depleting substances.

The Protocol has resulted in the phasing-out of the production of many such chlorine-and bromine-containing species – preventing not only millions of cases of skin cancer deaths and cataracts, but also reducing emissions of halogenated greenhouse gases by the equivalent of more than 10 billion tons of CO2
at the end of 2008.

All Montreal Protocol decisions have been based on the science findings of the UNEP/WMO ‘‘Scientific
Assessment of Ozone Depletion’’, carried out every 4 years. University of York researchers have been key
authors and contributors to this Assessment.


New evidence is emerging that atmospheric levels of short-lived chlorine substances not controlled by the Montreal Protocol are rapidly increasing.

Our work is investigating the key sources and sinks of such substances. We have previously shown that emissions of natural VSLS including CHBr3 and CH2Br2 from the marine biosphere represent a major global source of bromine, and we are working to identify how such sources may be impacted by climate change.

We have also shown that the ocean is a much stronger source of iodine than previously assumed. Complex cycling between the gas and aerosol phase may mean that transport of iodine into the stratosphere is possible, although so far there is a lack of observational evidence.