Air pollution from China blows across the Pacific Ocean and ends up over the US west coast -- and American consumerism is to blame for a portion of it, said a study.

On some days, nearly a quarter of the pollutants in the air over California, Oregon, Washington and Portland were initially spewed into the air in China, during the making of televisions, toys, cellphones and other products for export.

"We've outsourced our manufacturing and much of our pollution, but some of it is blowing back across the Pacific to haunt us," said co-author Steve Davis, a scientist at the University of California, Irvine said yesterday.

"Given the complaints about how Chinese pollution is corrupting other countries' air, this paper shows that there may be plenty of blame to go around," he added.

The research was led by Jintai Lin of Beijing's Peking University, along with co-authors from the United States and Britain.

The study found that 22 percent of carbon monoxide and 17 percent of black carbon emitted in China were associated with the production of goods for export.

Black carbon is a concern because it lingers in the atmosphere, doesn't wash away with rain and can travel long distances. Exposure can raise the risk of cancer, heart and lung disease and asthma.

The study also examined sulphur dioxide and nitrogen oxide.

"For each of these pollutants, about 21 percent of export-related Chinese emissions were attributed to China-to-US export," said the study, which appears in the Proceedings of the National Academy of Sciences.