BEIJING (REUTERS) - A Chinese company in the eastern city of Hangzhou has constructed a massive inflatable dome over the site of a closed down pesticide factory, state media reported on Wednesday.

While it covers an area the size of roughly three football fields, the 20,000-square-metre polyester dome still covers less that half the contaminated zone, according to the reports.

The factory was shut in 2009, but the stench emitted by the soil still forces nearby residents to cover their mouths and noses, according to the state media. The cause of the odour was not given.

Decades of unrestrained economic growth has hit China's environment hard, and anger over pollution has triggered protests that have helped make China's leadership more sensitive to the risks.

Reports of contaminated soil have become commonplace, and last month the environment ministry estimated that roughly 16 per cent of China's soil contained higher-than-permitted levels of pollution.

The ministry found that 82.8 per cent of the contaminated samples contained toxic inorganic pollutants, including cadmium, mercury, arsenic, chromium and lead.

Last month, China announced its first pilot project to treat metal pollution in soil and prevent farmland from further contamination, but critics say the efforts are underfunded and inefficient.