Methylmercury has caused severe pollution problems as a result of its toxicity.
It said around half of more than 70 Chinese cities monitored for air quality showed severe pollution over the weekend.
Kraków, an elegant city dotted with the remnants of its history as Poland's royal capital, suffers from the dirtiest air in a country plagued by severe pollution.
Companies in mineral and fossil fuel extraction clearly have poor dynamics from a sustainability perspective – they are running down their assets and often face severe pollution issues.
In January, an agriculture official admitted that millions of hectares of farmland could be withdrawn from production because of severe pollution by heavy metals.
Chinese society is prospering, even as it is cleaved by inequality and struggling with human rights abuses, corruption and severe pollution.
"We have a very young population currently being exposed [to severe pollution] and they will have very significant health problems in 15 to 20 years' time.
Its shallowness, coupled with the concentration of population, farms, and industrial plants in its watersheds, led to severe pollution by the mid-20th century.
It follows a course along the north of the Donets Basin industrial region, which uses much of its water and causes severe pollution problems.
Like other developing countries, it already bears much of the brunt of global climate change, including weather extremes like drought and severe flooding as well as severe pollution.
For much of the past year, the country has been plagued by damaging reports about severe pollution, dangerous exports, riots in Tibet and the ensuing disruptions to its Olympic torch relay by Tibet's sympathizers, among other groups.
