Cement factories in southern China have been blamed by an environmental expert for the choking pollution that blankets the region, a media report said Monday. Construction material producers in Foshan, a city in southern China’s Guangdong province, contributed heavily to the sulphur dioxide, nitrogen dioxide, ozone and soot in the air, according to Wu Dui, a researcher at the China Meteorological Administration.

"Foshan is unique because it has the country’s largest cluster of construction materials and ceramics factories emitting a large volume of pollutants through hundreds of stacks," Wu was quoted as telling the South China Morning Post. His assertions were based the findings of a six month air-quality study through southern China’s heavily industrialised Pearl River Delta, the report said.

According to the Guangzhou Marine Geological Survey heavy metals, oil, nitrogen, ammonia and other chemical materials are being pumped into the air to levels far higher than standards set by the State Environmental Protection Administration.