Industries in north-eastern China have released large quantities of an ozone-depleting gas into the atmosphere in violation of an international treaty, according to scientists..

An estimated 2.1 million deaths are caused by anthropogenic increases of fine particulate matter (PM2.5) while a further 470,000 are killed annually as a result of human-caused increases in ozone pollution.

Depletion of stratospheric ozone occurs over both hemispheres of the Earth. However, this phenomenon is significantly less severe in the northern hemisphere (Arctic) than in the southern hemisphere (Antarctica).