John Gummer, Secretary of State for the Environment, who is the ministers' host, wants them to agree on a target for cutting pollution levels to a point where the eye-itching, lung-irritating, photochemical smogs no longer occur during hot, still weather in Europe.
The pollutants come from road traffic, industry and power stations. A complex cycle of chemical reactions driven by intense sunlight leads to the formation of high levels of ozone, which affects some asthmatics and people with other chest problems.
Sometimes half or more of these pollutants originate in continental Europe and drift across the North Sea and the Channel into southern Britain - a phenomenon which the Sun newspaper calls "Frog smog". That is why nations have to act together to tackle the problem.
But UK officials concede that British smogs are largely home grown,and sometimes this pollution adds to ozone episodes in Europe. Nicholas Schoon