US failing to slash ozone levels because China's pollution is wafting across the Pacific, study claims

Progress slashing unhealthy ozone in the western United States has been largely undone by pollution wafting across the Pacific from China, according to a new study.

Scientists have long suspected this might explain why ozone levels along the US west coast remained constant despite a significant local reduction in ozone-forming chemicals.

The study, published in Nature Geoscience, is the first to make the case using satellite observations coupled with computer models of how air-borne molecules travel in the lower atmosphere, the authors said.

“The dominant westerly winds blew this air pollution straight across to the United States,” explained lead research Willem Verstraeten of the Royal Netherlands Meteorological Institute.

“In a manner of speaking, China is exporting its air pollution to the West Coast of America,” he said.

Nitrous Oxide emissions from vehicle traffic and industry, mixed with sunlight, create dirty-yellow blankets of ozone smog that sting the eye and scratch the throat.